Dry Tortugas National Park 

Dry Tortugas Light Station 

Keeper’s Residence 

Historic Structure Report 

Prepared for 

Dry Tortugas National Park 

Southeast Region, National Park Service 

by 

Lord, Aeck & Sargent Architecture 

2009 
 

Cultural Resources 

Southeast Region 

National Park Service 

100 Alabama St. SW 

Atlanta, GA 30303 

(404) 507-5847 

2009 

Historic Structure Report 

Dry Tortugas Light Station Keeper’s Residence 

Dry Tortugas National Park 

LCS#: 091388 (Dry Tortugas Keeper’s 

Residence) 

Cover Image: Early twentieth century image of Dry 

Tortugas Keeper’s Residence. 
 

Dry Tortugas National Park 

Dry Tortugas Light Station 

Keeper’s Residence Historic Structure Report 

2009 

National Park Service v 

Contents 

Management Summary .............................................................................................................. 1

Administrative Data .................................................................................................................... 5

PART 1 DEVELOPMENTAL HISTORY 

Historical Background and Context ..................................................................................................... 9 

 Discovery and Early Exploration of the Dry Tortugas ........................................................ 9 

 Aids to Navigation in the Dry Tortugas ................................................................................. 11

 Lighthouse Illumination .......................................................................................................... 12

 A New Light in the Dry Tortugas ........................................................................................... 14 

 Keepers and Their Duties ........................................................................................................ 15

 War and Disease ....................................................................................................................... 16 

 The Hurricane of 1873 ............................................................................................................. 18 

 Late Nineteenth Century Development ................................................................................ 19 

 The Spanish American War ..................................................................................................... 21 

 Bureau of Lighthouses ............................................................................................................. 21 

 The Carnegie Institution Marine Biology Laboratory ......................................................... 21 

 Early Twentieth Century Modernization .............................................................................. 23 

 The U.S. Coast Guard ............................................................................................................... 24 

 The National Park Service ....................................................................................................... 26

 

Chronology of Development and Use ................................................................................................. 29

 Original Construction .............................................................................................................. 29 

 Early Plan Development .......................................................................................................... 30

 The Keeper’s Residence is Funded ........................................................................................ 33

 Construction .............................................................................................................................. 34 

 The Keeper’s Residence Undergoes Gradual Changes ....................................................... 37 

 Changes in the 1960s and 1970s .............................................................................................. 38 

 Modifications in the Late 1980s .............................................................................................. 39 

 National Park Service Modifications ..................................................................................... 42 

Dry Tortugas Keeper’s Residence Timeline ........................................................................................ 43

Physical Description ............................................................................................................................... 45 

 

 Dry Tortugas Keeper’s Residence .......................................................................................... 45

 Character Defining Features ..................................................................................... 46 

 Site ................................................................................................................................ 47

 Structural Systems ...................................................................................................... 49 

 Exterior Features ........................................................................................................ 53

 Interior Features ......................................................................................................... 71

 Summary of Conditions ............................................................................................. 86

 
vi Dry Tortugas Keeper’s Residence HSR 

PART 2 TREATMENT AND USE 

 Requirements for Treatment and Use ..................................................................................................89 

 Ultimate Treatment and Use ..................................................................................................................93

 Alternatives for Treatment and Use ......................................................................................................97 

 Recommendations for Treatment and Use ..........................................................................................99 

Sources of Information ............................................................................................................. 105

 

Appendix A : Draft National Register Nomination Form 

Appendix B: Dry Tortugas Light Station Materials Analysis, Dry Tortugas, Florida, Building 

Conservation Associates, August, 2009. 

Appendix C: Various Specifications, Descriptions and Materials List for Keeper’s Residence 
National Park Service 1 

Figure 1: Early 1920s view of Keeper’s Residence taken during the final stages of construction. 

Management Summary 

The Dry Tortugas Keeper’s Residence was 

constructed in 1922-23 to provide much-needed 

residential living space for the principal 

lighthouse keeper and his family during a period 

of modernizing the Light Station. 

The Keeper’s Residence was one of several 

structures built to accommodate the light 

keepers, their families and the equipment and 

supplies necessary to maintain the Lighthouse 

and support habitation in this remote location. 

The Keeper’s Residence housed keepers and 

USCG personnel from its initial construction 

through the mid-1980s when the Lighthouse 

optic was automated, eliminating the need for 

continual occupation of the site. The decision to 

automate the lamp was made after the rotating 

mechanism of the existing second-order lens 

was damaged during repairs to the Lantern. 

In 1992, legislation was passed to abolish Fort 

Jefferson National Monument (designated by 

Franklin Delano Roosevelt in 1935) and 

establish Dry Tortugas National Park (DRTO). 

As part of the Park’s enabling legislation, 

Loggerhead Key, along with the resources of the 

Light Station (with the exception of the 

Lighthouse) were transferred from the United 

States Coast Guard to the National Park Service 

(NPS). As part of the 2007 Cooperative 

Agreement, the NPS was required to reserve a 

room within the Keeper’s Residence for the 

exclusive use of USCG personnel when at the 

Station. Under the Park Service’s management, 

public visitation to the Key has been limited. 

However, a relatively constant presence has 

been maintained at the site through the NPS’s 

Volunteer-In-Parks (VIP) program and various 

research initiatives. The former Kitchen building 

has generally been used to house volunteers 

while researchers and contractors have been 

accommodated within the Keeper’s Residence. 

In October 2008, Lord, Aeck & Sargent was 

contracted by the National Park Service to 

prepare a Historic Structure Report (HSR) for 

the resources of the Dry Tortugas Light Station. 
2 Dry Tortugas Keeper’s Residence HSR 

It was decided that three documents would be 

prepared, the first would address the Lighthouse 

and Oil House, the second, the Keeper’s 

Residence and the last document would address 

the remaining resources of the Light Station. 

This document addresses the Dry Tortugas 

Keeper’s Residence. 

During the first week of March 2009, a two 

member team from Lord, Aeck & Sargent (Rob 

Yallop and Glen Bennett) traveled to 

Loggerhead Key to undertake a physical 

inspection of the Light Station resources. In 

addition, Ms. Dorothy Krotzer of Building 

Conservation Associates also traveled to the site 

to collect mortar and paint samples for analysis 

(The results of this analysis are provided in 

Appendix A). Personnel from Lord, Aeck & 

Sargent spent a week on the island documenting 

the resources and collecting information to 

support preparation of the HSRs. A second brief 

visit was made to the site in June 2009 to collect 

some remaining information. 

Field notes, measurements, material sampling 

and photographs were collected for all of the 

structures as a means to record the existing 

conditions. With the exception of the mortar 

and paint sampling, no destructive testing was 

performed and no historic fabric was removed 

to facilitate the collection of information. All 

portions of the Keeper’s Residence were 

inspected during the review of existing 

conditions. 

Historic research included two trips to the 

National Archives and Records Administration 

in Washington D.C. and one visit to the 

Southeast Region National Archives in Morrow, 

Georgia to review documents, drawings and 

photographs held primarily in Record Group 26. 

The files held in the archives of Everglades 

National Park were also reviewed and a visit was 

made to the USCG offices in Miami to review 

records pertaining to their management of the 

site. Numerous other secondary sources were 

consulted in preparation of the HSR. 

The Park’s General Management Plan has 

addressed treatment and use of the Light Station 

through the establishment of a Historic 

Preservation/Adaptive Use Management Zone 

in the center of Loggerhead Key. Without being 

specific, this management zone prescribes that 

the resource of the Light Station will be 

primarily reserved for interpretive and 

educational opportunities. The structures will 

also be adaptively used to accommodate critical 

functions such as housing for volunteers, staff 

and research personnel and the storage of utility 

components and equipment. 

The Keeper’s Residence has undergone a series 

of modifications over time. During the 1950s 

while under the management of the USCG, the 

floor plan was altered and the plumbing system 

was updated. A fire detection system was added 

in the early 1970’s and the floor plan was altered 

again circa 1982. Major repairs took place in the 

mid-to-late 1980’s, including additional floor 

plan changes, building rewiring and installation 

of new fixtures and outlets, replacement of the 

fascia, soffit and gutters and installation of new 

flooring. Also at this time, gypsum board was 

hung over the existing plaster walls and ceilings, 

and new baseboards were installed. 

Additional changes to the Keeper’s Residence 

have occurred since the National Park Service 

assumed management of the Light Station in 

1992. The installation of centralized air 

conditioning, high efficiency appliances, and 

attic insulation occurred in 2002. 

The windows were replaced with Pella 

architectural series thermopane windows in 

2004. Although dates of installation are not 

known, other recent changes to the building 

include the installation of composition asphalt 

shingle roofing and metal hurricane shutters at 

each of the windows. 

While many of these changes have resulted over 

time due to the deterioration and damage caused 

by the marine environment and intense storms 

that frequent this region, other changes have 

been implemented as building systems 

technology has advanced and residential living 

styles have changed. 

Although the Keeper’s Residence has undergone 

these changes, it has retained a substantial 

amount of its historic integrity and continues to 

express its historic residential character. The 

residence retains its one-story rectangular plan 

with Craftsman-style detailing and hipped roof 

form with overhanging eave. 

The engaged front and side porches with 

tapered wood columns on brick piers with coral 
Management Summary 

National Park Service 3 

cement detailing are intact with all wood 

elements painted white. 

The residence retains its wood roof and floor 

framing systems and load-bearing brick masonry 

wall structure of buff yellow brick with 

contrasting red bricks alternating courses at 

building corners and diamond-shaped 

patterning. 

Though the original doors and windows have 

been removed, the original configuration of 

exterior openings has been retained, and the 

most recent replacement windows closely 

replicate the appearance of the historic 

windows. 

Despite the fact that non-historic materials have 

been installed at the interior ceilings, walls and 

floors, a portion of the historic plaster wall finish 

and wood crown molding remains visible above 

the gypsum board walls. 

The desire of the National Park Service to 

provide greater use of the Keeper’s Residence 

for continued residential purposes best suits the 

preservation of the building. 

The existing condition of the Keeper’s 

Residence does not present major obstacles to 

greater use, however there are several issues that 

should be addressed in order to correct 

deteriorating conditions and ensure 

preservation of the building. 

These include replacing damaged roof shingles, 

installing gutters and downspouts, repairing 

damaged screening at eave, replacing 

deteriorated window lintels and repointing 

adjacent damaged mortar joints, sealing joints 

between the front stairs and cheek walls, 

repointing critical areas of mortar loss and 

masonry joint cracking in the front porch piers, 

repairing damaged porch flooring, conducting 

regulated materials analysis to quantify presence 

of asbestos and lead paint, and repairing plaster 

cracks at interior wall surfaces. 

In addition, it is recommended that the 

building’s exterior character be restored to its 

1920s appearance to facilitate interpretation of 

the Light Station to this important period of 

modernization. Exterior character-defining 

features to be restored include replacing exterior 

doors to match character of historic doors and 

sidelights and installing wood shutters to match 

character of historic louvered wood shutters. It 

is also recommended that the building’s interior 

be rehabilitated to provide the necessary 

elements and systems to accommodate its use as 

housing for visitors to the island. 

Summary of Recommendations 

The following is a summary of the treatments 

recommended to preserve and rehabilitate the 

Dry Tortugas Keeper’s Residence and to prepare 

it for continued use. The recommendations have 

been organized into three “Work Packages” in 

response to limits on the amount of cyclical 

maintenance funding that can be requested by 

Park in a given year. Further information about 

the Work Packages and a Cost Estimate are 

included in Appendix E. 

General 

 Restore exterior of Keeper’s Residence 

to its 1920s appearance. 

 Rehabilitate interior for continued use. 

Work Package 1 – Priority Treatments 

including Masonry Repairs 

 Replace deteriorated lintels and conduct 

masonry repointing and repair of the 

associated exterior masonry. 

 Remove/replace corroded metal 

elements embedded within porch piers 

and conduct masonry repointing and 

stone repairs. 

 Remove hurricane shutter brackets and 

repair damage to masonry and sills. 

 Relocate tracks and install new 

hurricane shutter brackets with 

corrosion-resistant fasteners. 

 Repair and repoint exterior masonry 

walls. 

 Repair and repoint foundation walls. 

 Repoint stairs and separation at cheek 

wall. 
4 Dry Tortugas Keeper’s Residence HSR 

 Clean masonry. 

 Install smoke detection system and 

extinguishers. 

 Relocate passive solar water heater. 

 Relocate propane tanks and enclosure 

from in front of crawl space access. 

Work Package 2 – Exterior Carpentry and 

Roofing Repairs 

Roof 

 Repair/replace damaged roofing 

shingles. 

 Repair/replace damaged drip edge and 

soffit screening at eave. Repaint. 

 Install gutters and downspouts. 

 When replacing roofing in future, 

consider installing roofing material that 

matches the hexagonal pattern of 

original roofing. 

 Protect attic vent from moisture 

infiltration. 

Porches 

 Repair/replace damaged porch flooring. 

 Install hatch cover at side porch attic 

access. 

 Restore porch balusters to match 

historic condition. 

 Restore rear porch. 

 Repaint porch ceiling, eave and floors 

Doors and Windows 

 Replace non-historic doors with new 

doors matching character of historic 

doors. 

 Replace plywood in front door 

surround with sidelights matching 

historic condition. 

 Fabricate and install new wood louvered 

shutters matching those shown in 

historic images of the building. 

Work Package 3 – Interior Rehabilitation 

Interior 

 Repair cracking in plaster walls. 

 Patch holes in gypsum board wall and 

ceiling finishes. 

 Repair interior moldings. 

 Repaint interior areas of deteriorated 

paint finishes. 

 Remove carpeting and restore wood 

floor. 

 If the existing vinyl floor tile are 

damaged or deteriorate to the point of 

replacement, it would be appropriate to 

remove the tile and restore the historic 

wood flooring. 

 If the existing gypsum board ceiling 

finish is damaged or deteriorates to the 

point of replacement, it would be 

appropriate to remove the drywall to 

expose the historic wood ceilings. 

 Develop an “alternative minimum” 

approach to accessibility. 

Building Systems 

 Better educate users of the Station’s 

housing facilities about the limits of the 

electrical system and energy saving 

measures that will help mediate demand 

during peak usage periods and reduce 

strain on the system. 

 Repair/rewire faulty electrical outlets. 

 Maintain in place existing light fixtures. 

 Install new light fixtures at porch 

ceilings. 
Administrative Data 

National Park Service 5 

Administrative Data 

Resource Names and Numbers 

Building Name: Dry Tortugas Keeper’s 

Residence 

Structure No.: HS-24 

List of Classified Structures (LCS) No.: 091388 

Resource Location 

The Dry Tortugas Keeper’s Residence is located 

on Loggerhead Key within Dry Tortugas 

National Park. Located 65 miles west of Key 

West Florida, Dry Tortugas National Park 

encompasses an area of approximately 100 

square miles containing seven, small, sand and 

coral keys (islands) and the surrounding shoals 

and water. Loggerhead Key and Garden Key are 

the only inhabited keys within the Park. The 

Park’s central cultural feature, Fort Jefferson, is 

located on Garden Key, approximately 2 1⁄2 

nautical miles east of Loggerhead Key. Access to 

the Park is by boat or seaplane. The visiting 

public generally travels to the Park on 

commercial ferries operated out of Key West. 

The primary public docking facilities and 

debarkation points are on Garden Key. 

Loggerhead Key is the largest key in the Park 

measuring approximately 1 mile long and 700 

yards across and containing approximately 35 

acres. The Keeper’s Residence is among several 

historically significant buildings at the Dry 

Tortugas Light Station. The Light Station 

complex is located in the approximate 

geographic center of Loggerhead Key. 

Location:: Loggerhead Key, Dry Tortugas 

National Park 

Coordinates: Latitude 24° 38’ 00.021” N, 

Longitude 82° 55’ 13.958” W 

County: Monroe 

State: Florida 

Cultural Resource Data 

In 1984, a draft National Register nomination 

was prepared for the Dry Tortugas Light Station 

by National Park Service staff as part of a 

submission to the USCG, Department of 

Transportation. No further action was taken by 

the USCG regarding the nomination. The 

National Park Service subsequently conducted a 

review of the nomination in 1989 anticipating a 

potential transfer of the Light Station from the 

USCG. Based on this review, the nomination 

was updated in 1993 and submitted to the Acting 

Chief Historian of the National Park Service’s 

Washington Support Office for a second review 

in 1995. No further action was taken with regard 

to the draft nomination. 

Dry Tortugas National Park was established in 

1992 by Public Law 102-525 to “preserve and 

protect for the education, inspiration, and 

enjoyment of present and future generations 

nationally significant natural, historic, scenic, 

marine, and scientific values in South Florida.” 

Under [36 CFR 60.1(b) (1)], historic units of the 

National Park System are automatically given 

National Register of Historic Places status by 

virtue of their incorporation into the park 

system. Thus, the Dry Tortugas Light Station 

was listed on the National Register of Historic 

Places as part of Dry Tortugas National Park. 

The following information is taken from the 

draft National Register nomination for Dry 

Tortugas Light Station completed in 1984 and 

updated in 1993. 

National Register Criteria A and C 

Period of Significance: 1855 – present (1995) 

Significant Dates: 1856-1858, 1920s 

Acreage of Proposed District: 1.85 

Significance 

The draft national register nomination proposes 

a broad period of significance for the property 

spanning from its initial construction date 

through to the “present,” or 1995, the year the 

draft nomination was submitted to the 

Washington Support Office. This approach 
6 Dry Tortugas Keeper’s Residence HSR 

Figure 2: Maps showing location of Dry Tortugas National Park, Loggerhead Key and the individual 

structures of the Dry Tortugas Light Station. 

Oil House 

Loggerhead Key

Dry Tortugas National Park Vicinity Map 

Dry Tortugas National Park 

Cuba 

Florida 

Dry Tortugas Lighthouse 

Loggerhead Key 

Boathouse 

Kitchen Building 

New Oil House 

1922 Keeper’s Residence 

Concrete Cistern 

Brick Cistern 

Brick Cistern 

Concrete Cistern 
Administrative Data 

National Park Service 7 

suggests the Lighthouse derives its primary 

significance from its function as an aid to 

navigation and is inclusive of the entire period it 

has been active. This approach acknowledges all 

epochs of the Light Station’s history including 

the National Park Service’s management of the 

site during the last two decades. 

Specifically, the draft nomination provides the 

following statement about the Light Station’s 

significance. 

“The light station is significant primarily for 

its role in facilitating America’s ocean-borne 

commerce and as a notable example of the 

kind of civilian public works project 

undertaken by Army engineers prior to the 

Civil War. While the Lighthouse is clearly 

the most important structure within the 

boundaries of the nominated area, there 

were several ancillary structures built at the 

same time as the lighthouse, and also from 

the 1920s, a period in which the station was 

extensively modernized.” 

It is recommended that the draft national 

register nomination be updated based on the 

research collected in preparing the HSRs and 

resubmitted for formal acceptance. 

Related Studies 

Hellman, Robert and David M. Brewer. 

Archeological Survey of Loggerhead Key, 

Dry Tortugas National Park. Southeast 

Archeology Center (SEAC), National 

Park Service, 2003. 

Kenneth Smith Architects Inc., and Bender & 

Associates, Architects P.A. for the State 

of Florida Department of State, Division 

of Historical Resources and Department 

of Community Affairs, Florida Coastal 

Management Program. Florida 

Lighthouse Study 2002 

National Park Service Draft National Register of 

Historic Places Registration Form 1993 

National Park Service. General Management 

Plan Amendment, Dry Tortugas National 

Park. 2002 

National Park Service National Register 

Programs Division, Preservation 

Services Branch for the Department of 

Transportation, United States Coast 

Guard, Seventh District, Rehabilitation 

Report and National Register Nomination 

for the United States Coast Guard Light 

Station, Dry Tortugas Lighthouse, 

Loggerhead Key Florida. October 1984 
8 Dry Tortugas Keeper’s Residence HSR 
National Park Service 9 

Historical Background and 

Context 

The historical background of the Dry Tortugas 

Light Station is documented by historians, 

Love Dean in Lighthouses of the Florida Keys

and Neil Hurley in Lighthouses of the Dry 

Tortugas: An Illustrated History. These along 

with Russ Holland’s America’s Lighthouses: 

Their Illustrated History since 1716 and Edwin 

C. Bearss’ Shipwreck Study-The Dry Tortugas

contributed to the development of the 

historical background and context. The 

following narrative draws upon these histories 

and references them when cited. The 

historical background also relies on the 

“clipping files” and other primary sources 

related to the Dry Tortugas Light Station 

found in National Archives Record Group 26. 

Discovery and Early Exploration of 

the Dry Tortugas 

Juan Ponce de Leon is credited with the 

discovery in 1513 of 11 sand and coral islands 

located at the southwestern tip of the Florida 

Keys. Because sea turtles were in abundance, 

he named the islands “Las Tortugas,” meaning 

the turtles. At the time of Ponce de Leon’s 

discovery, hundreds of turtles were present on 

the shores of these islands along with pelicans 

and the now-extinct Caribbean monk seal.1

Several accounts describe Ponce de Leon’s 

crews capturing over a hundred turtles in one 

night - turtles were a significant source of food 

for mariners. 

The first recorded shipwreck in the area 

occurred in 1622 when the Nuestra Senora del 

Rosario ran aground on one of the keys of the 

Tortugas. The survivors and their rescuers 

 

1

 Bearss, Edwin C., Shipwreck Study-The Dry Tortugas, 

Washington, DC: Eastern Service Center-Office of History and 

Architecture, United States Department of the Interior, 

National Park Service, April 15, 1971,1. 

reportedly camped on the island that would 

later be named Loggerhead Key.2

Florida was under Spanish rule from 1513 

until 1763, when it was ceded to Britain. While 

under British rule, Las Tortugas were surveyed 

by T. Jefferys in 1763, by Bernard Romans in 

1766, and by George Gauld in the 1770s. 

Gauld’s maps, published in 1773, were used 

widely for navigation of the gulf coast off 

British West Florida. Due to the lack of fresh 

drinking water, or possibly “in contradiction 

to the vast tract of wet reef which at low water 

nearly reaches the surface,” Las Tortugas 

eventually became known as the Dry Tortugas. 

On his charts, Gauld named the individual 

islands that made up the Dry Tortugas 

including Loggerhead “Turtle” Key.3

In 1783, following its participation in the 

American Revolution, Spain regained Florida, 

and maintained it as a colony until 1821. Spain 

encouraged settlement of the region through 

land grants, but Florida remained sparsely 

populated well into the nineteenth century. By 

1845 when Florida became a state it had only 

60,000 residents. 

Given their location at the intersection of the 

Gulf of Mexico and the Atlantic Ocean where 

the swift Gulf Stream current flows though the 

Straits of Florida, the Dry Tortugas witnessed 

considerable shipping traffic. Westward 

expansion in the United States led to an 

increase in the transport of goods from the 

interior of the continent to the urban centers 

along the east coast. After passing through the 

open waters of the gulf, most ships heading 

east avoided the Dry Tortugas by taking a 

 

2

 Hellmann, Robert and David M. Brewer, Archaeological 

Survey of Loggerhead Key, Dry Tortugas National Park,SEAC 

Accession No. 1341, 2003. 

3

 Dean, Love, Lighthouses of the Florida Keys, Inc., Sarasota, 

Florida: Pineapple Press, 1998, 75. 
10 Dry Tortugas Lighthouse Keeper’s Residence HSR 

Figure 3. Map produced in 1838 based on Gauld’s earlier 1773 survey of the Dry Tortugas. Note the map 

identifies Loggerhead “Turtle” Key. 
Historical Background and Context 

National Park Service 11 

Figure 4. Undated nineteenth century view of 

Garden Key lighthouse within the parade 

ground of Fort Jefferson. 

southerly route and navigating along the 

Cuban coastline. Stormy weather or a 

captain’s inexperience could result in ships 

veering off course and foundering in the 

shallow reefs of the Keys. Not only did 

mariners have to be mindful of the hazardous 

sailing conditions, but they also had to keep a 

vigilant watch for pirates cruising these same 

waters in search of vessels they could exploit. 

Salvaging, or wrecking as it was also known, 

became a lucrative business in the Florida 

Keys. Dozens of vessels and hundreds of men 

were active in the trade which became highly 

organized and regulated. Wreckers had to 

hold a license issued by the Federal Court to 

legitimately take part in salvaging activities. 

During the nineteenth century, the Keys 

claimed hundreds of ships carrying millions of 

dollars of cargo which was eventually salvaged 

and liquidated in the auction houses of Key 

West. In the Dry Tortugas, the natural harbor 

at Garden Key provided safe anchorage for the 

wreckers from where they could observe the 

surrounding keys and quickly respond to any 

ship running aground or needing assistance.4

 

Aids to Navigation in the Dry 

Tortugas 

On August 7, 1789, the new Congress of the 

United States, with its ninth act, assumed 

responsibility for managing the nation’s 

lighthouses and navigational aids. Prior to this, 

each state sited, built, and managed 

lighthouses as needed. The U.S. Lighthouse 

Establishment was the body created by the 

government to oversee the construction and 

operation of the lighthouses. Initially, 

Secretary of the Treasury, Alexander 

Hamilton, directly appointed keepers and 

negotiated construction contracts. Even 

President Washington signed and approved 

lighthouse contracts during the first years of 

his presidency. In 1792 oversight of the 

lighthouses was passed to the Secretary of 

Revenue, and then back to the Secretary of 

Treasury in 1820 when Stephen Pleasonton 

became the Fifth Auditor of the Treasury. 

During the early part of the nineteenth 

century, after the U.S. acquisition of the 

 

4

 Ibid., 78 

Louisiana Territory, shipping through the 

Florida Straits increased. Lieutenant 

Commander Matthew C. Perry was assigned 

to survey the Keys in 1821, after portions of 

Florida became a U.S. territory. Perry noted 

the difficult sailing conditions and reported to 

Congress that four light stations would be 

necessary to alleviate nautical risk within the 

Florida Keys. These included Southwest Key, 

Sand Key, Key Largo and Cape Florida. 

Congress responded with a recommendation 

to build lighthouses at Key West, Cape Florida 

and the Dry Tortugas. In the Dry Tortugas, 

Garden Key was selected as the most suitable 

location for a lighthouse. Construction of the 

Garden Key lighthouse began in August of 

1824 and continued until the lamp was lit on 

July 4, 1826. The focal plane of the light was 70 

feet above sea level and the lantern was fitted 

with 23 lamps and 14-inch reflectors.5

 

Despite construction of a lighthouse on 

Garden Key, over the next two decades, 

mariners continued to complain about the 

inadequacy of navigational aids in the Dry 

Tortugas. The new light was not only difficult 

to see in the hazy conditions of the gulf, its 

location six miles from the outer southwest 

edge of the reefs, and another eight miles from 

the northeastern shoals, meant that ships 

would find themselves in dangerous waters 

before the light was visible. The light 

constructed on Garden Key was simply not tall 

enough to adequately mark the hazards of the 

Dry Tortugas. 

 

5

 Ibid., 77.
12 Dry Tortugas Lighthouse Keeper’s Residence HSR 

Figure 5. Captain Horatio G. Wright. 

Numerous ship wrecks, including the Concord

and Florence in 1831 and the America in 1836, 

were blamed on the poor visibility of the 

Garden Key lighthouse. In an 1836 interview 

with the Key West Inquirer, John Thompson, 

assistant light keeper at Garden Key, described 

the need for two additional lighthouses in the 

Dry Tortugas—one on the easternmost and 

the other on the westernmost keys.6

 The 

newspaper endorsed Thompson’s position.

Others voiced their opinion directly to the 

Lighthouse Board. William Whitehead, the 

Collector of Customs at Key West, wrote to 

Stephen Pleasonton in1836: 

Should it not be thought advisable to have 

all the appropriations made in one year, I 

would designate as being worthy of 

attention first the two light houses 

recommended for the Tortugas in place of 

the one now there. Many vessels have 

grounded there during the last year in 

consequences of inadequacy of the 

present light which I have every reason to 

believe does not arise from any neglect of 

those in charge.7

Meanwhile, in 1842, twenty-six year old 

Captain Horatio Gouvenor Wright was 

selected and charged with leading the 

construction of a massive fortification planned 

for Garden Key. Following conflicts with 

Spain and England regarding border disputes, 

President Tyler and Congress were persuaded 

to set aside four million dollars for military 

installations at Key West, Key Biscayne and 

the Dry Tortugas. In June 1844, President 

Tyler signed appropriations for the initial 

phase of construction of the fortification that 

would later be named Fort Jefferson. With the 

capacity to house 1,500 men, arm three tiers 

with 450 weapons, and to stand 50 feet off the 

water, Fort Jefferson was designed to be the 

largest “Third System” fort in America. The 

walls of the proposed fort were to be laid out 

in a manner that would encompass the 

existing Garden Key lighthouse and keeper’s 

dwelling. 

Shipping activity in the Dry Tortugas escalated 

to an unprecedented level as supplies of men 

 

6

 Bearss, 14. 

7

 Hurley, Neil E. Lighthouses of the Tortugas, An Illustrated 

History, Alexandria, Virginia: Historic Lighthouse Publishers, 

1990, 18. 

and material were sent to Garden Key. 

Complaints about the light continued until 

Pleasonton finally ordered several 

reconnaissance trips by his staff to assess the 

conditions. Adam Gordon, Lighthouse 

Superintendent at Key West, along with 

Captains William H. Chase and George 

Dutton of the Army Corps of Engineers, were 

sent to the Dry Tortugas to evaluate the light 

on Garden Key. They agreed the light was too 

low and dim to provide adequate aid to 

navigation and recommended that the light be 

relocated to Loggerhead Key. In the interim, 

Winslow Lewis was sent to inspect the 

lighthouse to see if anything could be done to 

improve its effectiveness. Lewis made minor 

adjustments to the lamp, but these proved to 

be ineffective and complaints continued. 

Lighthouse Illumination 

American lighthouses of the nineteenth 

century, including the one at Garden Key, 

were lit primarily with Argand oil lamps. In 

1781, Amie Argand developed a ring-shaped 

wick that allowed air to flow through and 

around the flame and thus produce a brighter, 

cleaner fire. The same Winslow Lewis that was 
Historical Background and Context 

National Park Service 13 

Figure 6. Schematic showing how the Fresnel 

lens concentrated light from a single source 

into a horizontal beam. 

sent to make adjustments to the Garden Key 

light had developed and promoted a silver 

metallic, parabolic reflector assembly to be 

used with the Argand lamp. Lewis had 

successfully lobbied the Collector of Customs 

in Boston, Congress, and members of the 

Lighthouse Establishment, and his apparatus 

became the standard used in American 

lighthouses during first quarter of the 

nineteenth century. Lewis was paid $60,000 

for a patent to the system, and most 

lighthouses were fitted with his apparatus by 

1815.8

 

Lewis’ system was an improvement on the 

various wicks and fuels previously used, but 

the Fresnel lens was concurrently being 

developed and would eventually surpass the 

Argand lamp and Lewis’parabolic reflector 

system in light quality and intensity. 

Developed by Augustin Fresnel, a French 

physicist, the Fresnel lens resembled a large 

glass beehive surrounding a single lamp. Asked 

by the French Commission on Lighthouses in 

1819 to help improve the illumination system, 

Fresnel worked with Claude Mathieu, his two 

brothers—Lenor and Fulgence, and Monsieur 

Talbouret to develop the new lamp 

technology. He also worked with Francois 

Soleil, Sr., a Parisian optician and glass 

manufacturer. 

The design intent of the Fresnel lens was to 

refract all of the light emitted from the source 

into one concentrated horizontal beam. By 

compounding the light beams in the lens a 

 

8

 Holland, Francis Ross, America’s Lighthouses: Their Illustrated 

History Since 1716, Brattleboro, Vermont: Stephen Greene 

Press, 1972,15. 

stronger and brighter signal was produced. By 

1821, Fresnel’s design was refined into an 

assembly of eight panels of concentric circular 

lenses with catadioptric prisms at the top and 

bottom of the panels. The lenses were made 

with triangular shaped glass that concentrated 

the light into a narrow horizontal beam. In 

1824, the first fixed Fresnel lens was 

constructed along with separate flash panels 

that were made to revolve around the light and 

produce two or four flashes per revolution. 

The flashes helped to distinguish the lights 

from stars or other lighthouses. This new 

Fresnel technology produced a bright, narrow 

sheet of concentrated light emitting from the 

lighthouse, which could be manipulated 

multiple ways for signaling sailors.9

 

Under Pleasonton’s guidance, the lighthouse 

system grew from 55 lighthouses in 1820, to 

331 in 1852. Despite development of the 

French Fresnel lens and its widespread use in 

Europe, Pleasonton continued to favor the 

Argand lamps and parabolic reflector system. 

His reason for not using the newer Fresnel 

technology, he said, was based on budgetary 

considerations. It has also been suggested that 

Pleasonton’s personal friendship with 

Winslow Lewis translated into a loyalty to 

Lewis’ seemingly inferior system. Pleasonton’s 

resistance to adopt the Fresnel technology 

resulted in mounting criticism of the Treasury 

Department’s management of the lighthouse 

system. Eventually this led Congress to direct 

the Secretary of the Treasury to investigate the 

Lighthouse Establishment. Ultimately the 

decision was made to: 

discharge all the administrative duties of 

said office relating to the construction, 

illumination, inspection, and 

superintendence of light-houses, light 

vessels, beacons, buoys, seamarks, and 

their appendages, and embracing the 

security of foundations of works already 

existing, procuring illuminating and other 

apparatus, supplies, and materials of all 

kinds for building and for rebuilding 

when necessary, and keeping in good 

repair, the light-houses, light-vessels, 

beacons, and buoys of the United States.10

 

9

 Ibid., p. 18. 

10 Light-house Appropriations Bill. Statutes at Large of the 

United States of America 1789-1873, 32nd Congress, 1st sess., 

vol.10, August 1852, 119. 
14 Dry Tortugas Lighthouse Keeper’s Residence HSR 

Figure 7. Section through a typical first-order 

lantern equipped with a Fresnel lens. 

An outcome of the investigation was the 

creation of the U.S. Lighthouse Board. This 

newly formed body would be made up of four 

high ranking military officers, two from the 

Navy and two from the Army along with two 

civilians of “high scientific attainments.” The 

Board would also divide the country into eight 

districts, expand inspection and engineering 

services, set up a central supply depot, begin 

publishing an annual “Light List”, and 

encourage the use of new technology such as 

the Fresnel lens. 

A New Light in the Dry Tortugas 

The Seventh District established by the 

Lighthouse Board included the Dry Tortugas, 

extending “from Cape Carnaveral [sic] lighthouse, Florida, to include Cedar Keys, 

Florida.” The office of the Superintendent of 

the Seventh District was located at Key West.11

The newly formed Board began immediately 

equipping existing and new lighthouses with 

Fresnel lenses. In the Dry Tortugas, the focus 

of the Board was to respond to decades of 

complaints by providing additional 

navigational aids including the construction of 

a new lighthouse on Loggerhead Key. 

 

11 Organization and Duties of the Lighthouse Board: 

Regulations, Instructions, Circulars, and General Orders, 

Washington DC: Government Printing Office,1871, 53. 

Additionally, the light on Garden Key was 

slated for retooling including the installation 

of a fourth-order Fresnel lens to service the 

immediate harbor traffic. The new lighthouse 

proposed for Loggerhead Key was to be 

equipped with a first-order lens—the largest 

lamp available. 

In 1855 Lieutenant T.A. Jenkins, United States 

Secretary of the Lighthouse Board, requested 

that Capitan H.G. Wright, overseer of 

construction at Fort Jefferson, submit a 

preliminary sketch and estimate for the new 

lighthouse. Wright provided a response to 

Jenkins on September 23rd, but it appears there 

was some confusion about the final location of 

the lighthouse, as his preliminary sketches, 

estimates, and letter are prepared for a project 

on Garden Key. 

It is proposed to first lay a grillage, as 

shown on the sketch, the top of which 

shall be on a level of those in the bastion of 

the fort....I cannot make any satisfactory 

estimate for the keeper’s dwelling, as I do 

not know what allowance of room for 

each person is authorized by the board, 

therefore none is submitted. There is now 

a wooden house, built for the keeper in 

1847, which contains two lower rooms, 

with hall, two half attic rooms and a 

detached kitchen, which if sufficiently 

capacious, will answer the purpose for 

some years to come...The privy should be 

built over a vault communicating with the 

sewers of the work, the cost of vault which 

will be not far from $100.

12

Ultimately the location for the new lighthouse 

was resolved and on August 18, 1856, 

Congress appropriated “for rebuilding the 

light-house, on a proper site, at Dry Tortugas 

and fitting it with first-order apparatus, thirtyfive thousand dollars.”13 

In the same year, Wright was replaced by 

Captain Daniel P. Woodbury of New 

Hampshire. Woodbury who would now 

oversee construction of the fort and the 

lighthouse made several design changes to 

 

12 Dry Tortugas Light Station Clipping File, Appendix no. 17, 

H.G. Wright, Capitan of Engineers, Fort Jefferson, FL, to 

Lieutenant T.A. Jenkins, U.S.N., Secretary, Light-house Board, 

Washington, D.C., September 23, 1855, Record Group 26, NA. 

13 Light-house and Appropriation Bill, Statutes at Large of the 

United States of America 1789-1873, 34th Congress, 1st sess., 

August 1856, vol.11, 99. 
Historical Background and Context 

National Park Service 15 

Wright’s original proposal. According to Love 

Dean, Woodbury modified the dimensions of 

the tower, construction of the steps, masonry 

detailing and connection details between the 

lantern and the tower. He also configured the 

brick to corbel out below the Watch Room, 

forming the floor of the galley above.14

Construction of the lighthouse on Loggerhead 

Key began in 1857 and within a year the tower 

was complete. The first-order Fresnel lens was 

manufactured by the L. Sautter & Company. 

During the conversion to Fresnel lenses, the 

U.S. Lighthouse Board generally divided their 

purchases equally between the two primary 

lens manufacturers; L. Sautter & Company 

and Henry LePaute. 

In 1852, Louis Sautter bought the business 

started by Francois Soleil, Sr., with whom 

Fresnel worked to develop the Fresnel lens. 

Soleil’s business passed to his son-in-law, Jean 

Jacques Francois and onto his son-in-law, 

Theodore Letrouneau before it finally left the 

Soleil descendants. Sautter & Company 

shipped their first lens to America in 1853 for 

the lighthouse at Alcatraz Island. 

Sautter continued working with the glass 

manufacturer St. Gobain in Paris to make 

bigger and better glass pieces. Through 

acquisition and mergers, the company evolved 

to include electrical generators and 

searchlights. The company’s lights were used 

to illuminate the Champs-Élysées and the Arc 

de Triomphe in the late nineteenth century.15

By 1858 the lighthouse and buildings of the 

Dry Tortugas light station were complete. The 

station consisted of several structures sited in 

the middle of Loggerhead Key including the 

150- foot brick lighthouse, a detached two 

story oil house, a two-story keepers’ dwelling, 

a separate two-story kitchen, and two brick 

cisterns and several privies. A boathouse 

would not be constructed until 1871. 

Keepers and their Duties 

Benjamin Kerr was the first keeper assigned to 

the light station on Loggerhead Key. He was 

 

14 Dean, 84. 

15 Tag, Thomas, The Sautter Lens Works Producers of the 

Fresnel Lens, U.S. Lighthouse Society’s, The Keeper’s Log, 

Summer, 2005, www.uslhs.org. 

transferred from Garden Key in 1858 with a 

salary of $600 a year and brought with him, 

Henrietta his wife, and seven children. Kerr 

was employed at the Dry Tortugas light station 

until 1861, when he was replaced by James P. 

Lightbourn. Besides being named the first 

keeper of the Dry Tortugas Lighthouse, Kerr’s 

notoriety stems from an incident in which 

both of his assistant keepers allied with his 

wife and one daughter to “make an attempt on 

his life.”16 According to G. Phillips who was 

stationed at Fort Jefferson at the time, Kerr 

and one of his daughters arrived at Garden 

Key in a small boat, after having escaped from 

Loggerhead Key. Kerr and his wife apparently 

reconciled and managed to finish their 

assignment with no further incidents. 

The Organization and Duties of the Lighthouse 

Board set forth the requirements for 

lighthouse keepers. A few of the fundamental 

requirements established by the Board are 

listed below: 

LIV. Keepers were required to be over 18 

and be able to read and write, and be in 

every respect competent to discharge the 

duties of the keeper.... 

LV. Men of intemperate habits and those 

who are otherwise mentally or physically 

incapable of performing the duties of the 

light keepers, must not be nominated for 

appointment by superintendents of lights. 

LVII. Women and servants must not be 

employed in the management of lights, 

except by the special authority of the 

Department.17 

Pay was established at the keeper’s 

appointment and was begun when they 

entered their duties. The keepers were 

permitted to select their assistants, but 

keepers’ families were allowed to be 

nominated only in “rare and exceptional 

cases.”18 The keeper’s duties included keeping 

all aspects of the light station clean and in 

good working order, lighting and maintaining 

lamps, painting and maintaining all finishes 

both inside and out of all buildings, and 

maintaining clothing and accessories 

necessary to service and protect the light. 

Other duties included providing reports to the 

 

16 Dean, 87. 

17 Organization and Duties of the Lighthouse Baord, 60. 18 Ibid. 
16 Dry Tortugas Lighthouse Keeper’s Residence HSR 

district office, maintaining safe and dry places 

for cleaning supplies, and logging in and out 

supply deliveries. 19

As one might expect, life on Loggerhead Key 

was particularly isolated. With a few 

exceptions, keepers remained at the light 

station for short durations. There were 10 

keepers assigned to the Dry Tortugas station 

between 1858 and 1912. 

During the 1860s, rations for each lighthouse 

keeper and assistant keeper, in addition to 

their salary, included: 

40 pounds of salt pork, 52 pounds of salt 

beef, 100 pounds of flour, or 80 pounds of 

ship biscuit, 11 1⁄2 pounds of brown sugar, 6 

pounds of coffee, or 1 1⁄2 pound tea, 5 pounds 

rice and 2 gallons beans or peas per quarter20 

A break in the monotony came for the keepers 

and their families when on occasion they 

would be invited to socialize with the families 

of officers stationed at Fort Jefferson. 

Alternately at times the lighthouse keeper 

would host parties on Loggerhead Key, usually 

in conjunction with turtle turning expeditions. 

“Turtle turning” involved turning large turtles 

on their backs, thereby rendering them 

helpless and unable to escape. The turtle 

turning parties were often accompanied by the 

sharing of food, music, and dancing. 

Later during the twentieth century, keepers 

were restricted to living on the island without 

their families. In a 1938 letter from the 

Superintendent of Lighthouses to the 

Commissioner of Lighthouses, the 

Superintendent advocates for familial visits for 

keepers during the summer months. 

Responding to a proposed change in policy 

that would eliminate this privilege, the letter 

emphasizes the remote and isolated conditions 

at the station: 

Dry Tortugas Light station, Fla., is possibly 

one of the most isolated as well as attractive 

and efficient stations in the Service... There is 

no intention to make the station a resort; it is a 

condition that has existed for many years with 

nothing but beneficial results to the keepers 

and their families and this office believes that 

the best interest of the Service is being 

 

19 Ibid., 88-89. 

20 U.S. Lighthouse Board, Registers of Lighthouse Keepers, 

1845-1912, National Archives Southeast Region, Morrow, 

Georgia. 

conserved in making no changes. With 

unrestricted privileges of this nature being 

enjoyed by the Carnegie Institutions 

Biological Station on the same reservation 

together with the other reasons it is 

recommended that no changes or restrictions 

in this respect be made....In reference to 

inquiry as to whether or not they be quartered 

in the station buildings, Bureau is advise that 

such is the case and the keepers and their 

families are perfectly satisfied to subject 

themselves to the slight inconvenience for the 

pleasure and privilege of having these relatives 

and friends with them as requested. It has 

been the experience of this office that these 

keepers feel that these dwellings are their 

homes, for which they pay more rent than 

they are worth, in addition to having to 

maintain homes elsewhere.21 

Even into the 1980s, lighthouse keepers with 

the Coast Guard reinforced the lonesome and 

isolated nature of their duties. Most 

assignments for unwed officers were for six 

weeks with three weeks on shore and 

assignments for married officers were typically 

four weeks with two weeks on shore. “The 

biggest complaint was the absence of women 

and having to cook for each other.”22

War and Disease 

Florida seceded from the Union on January 

10, 1861, but the Dry Tortugas remained 

under the command of Union forces 

throughout the War. The Union successfully 

blockaded St. Augustine, Jacksonville, Key 

West and Pensacola. Still, some smaller vessels 

were able to smuggle goods such as cattle, 

crops and salt to Confederate sympathizers. 

While most of the battles of the Civil War took 

place in other states, approximately 16,000 

Floridians left home to fight in the war. The 

battles of Olustee (near Tampa Bay) and 

Natural Bridge (near Tallahassee) were both 

won by the Confederates and Tallahassee was 

the only state capital in the Confederacy not 

seized by Union Troops. 23

 

21 Superintendent of Lighthouses to Commissioner of 

Lighthouses, 08 June 1938, Record Group 26, NA, Washington, 

DC. 

22 Hurley, 59. 

23 Florida Center for Instructional Technology, College of 

Education, Florida’s Role in the Civil War: “Supplier of the 

Confederacy”, University of South Florida, 2009 

http://fcit.usf.edu/Florida/lessons/cvl_war/cvl_war1.htm. 
Historical Background and Context 

National Park Service 17 

Figures 8 and 9. Portions of an 1862 map of Dry Tortugas showing the first depictions of the light station. 

Loggerhead Key is shown in plan (above) and the lighthouse can be seen in elevation beyond Fort 

Jefferson within the cartouche (below). 
18 Dry Tortugas Lighthouse Keeper’s Residence HSR 

Figure 10. Elevation of iron tower proposed 

to replace storm-damaged masonry tower 

During the War, the 47th Regiment of the 

Pennsylvania Veteran Volunteers were 

stationed at Fort Jefferson and by 1865 nearly 

two thousand people were living on Garden 

Key. The installation was used primarily as a 

military outpost and prison during the war and 

was never fired upon or fired a shot in conflict. 

A yellow fever outbreak in 1867 resulted in the 

Light Station falling into disrepair for several 

years. During the period between 1867 and 

1871 Loggerhead Key was used as quarantine 

station for military personnel, which strained 

resources and impeded maintenance of the 

buildings. By 1871 the outbreak had subsided 

and various maintenance projects were again 

underway. 

A second outbreak of yellow fever affected the 

Dry Tortugas in September of 1873, requiring 

all healthy soldiers on Garden Key to once 

again be relocated to Loggerhead Key. During 

the outbreak, thirty people were infected 

resulting in 12 casualties. The healthy were still 

on Loggerhead Key when the hurricane of 

1873 hit the island. 

The Hurricane of 1873 

The hurricane that struck the Dry Tortugas on 

October 6, 1873, initially formed near the 

Leeward Islands, drifted west towards the 

Yucatan Peninsula, then backtracked through 

the lower Gulf of Mexico, before it curved 

northward and passed over the towns of Punta 

Rassa and Melbourne on the east coast of 

Florida. Although the track of the hurricane 

took the eye north of the Dry Tortugas, it 

delivered a damaging blow to the Light 

Station. 

The initial evaluation of the storm-damaged 

Light Station was bleak. The Lighthouse was 

reported to be in dangerous condition and it 

was initially recommended that the entire 

tower would need to be rebuilt. 

Because Loggerhead Key was still under a 

yellow fever quarantine and contact with the 

island was limited, only temporary repairs 

could be made following the storm. 

The walk in front of the keeper’s dwelling 

has been cemented and the waterconductors to the cisterns repaired. The 

cisterns have been cleaned and repaired, 

and wooden shutters for the towerwindows have been made, painted and 

hung. It is proposed, during the coming 

season, to make careful examination with 

a view to determining on plans for the 

foundation of a new tower.24

Congress appropriated $75,000 for repairs to 

the Lighthouse and plans were prepared for a 

new structure. In contrast to the existing 

masonry tower, the design of the replacement 

structure would be entirely of cast iron. 

By 1875 the upper portion of the lighthouse 

had been extensively repaired, anchors were 

extended down through the lighthouse walls 

 

24 Ibid. 
Historical Background and Context 

National Park Service 19 

Figure 11. Undated nineteenth-century view of the Dry Tortugas light station looking northeast.

to secure the lantern and the tower received its 

distinctive daymark. The upper portion of the 

tower was painted black and the lower portion 

was painted white. The black color was 

supposed to help dampen reflections, contrast 

with the white clouds and show a distinct 

color pattern for sailors.25 

The work was completed just as a second 

hurricane swept through the Dry Tortguas. 

The repairs held and were closely monitored 

during the ensuing years. Ultimately it was 

decided that a new lighthouse would not be 

necessary. 

During this same period, discussions were 

held about the inadequacies of the Garden 

Key Lighthouse and its placement within the 

parade ground of Fort Jefferson. After another 

hurricane damaged the Garden Key 

Lighthouse, plans were made to replace it with 

an iron structure to be located on top of 

bastion C of the Fort. The original Garden Key 

Lighthouse was demolished and on April 5, 

1876, the new cast iron light tower was lit.26

 

25 Hurley, 39. 

26 Hurley, 41. The choice to construct the new tower out of 

iron was a strategic military decision. If the fort came under 

attack, a brick tower was considered more dangerous because 

of the heavy shrapnel produced if hit by shells. 

Late Nineteenth-Century 

Development 

Through the late 1870s, minor repairs were 

made to several of the Station’s structures, and 

in 1880, a new boathouse was built. From 1888 

to 1910, Prussian George Billberry served as 

keeper of the Light Station. During his service, 

many repairs and upgrades were made to the 

Station buildings. From 1880 through the 

1890s, mineral lamps—otherwise known as 

Luchaire incandescent oil vapor lamps 

(i.o.v.)—became the method of illumination. 

New glass was installed in the lantern, wash 

houses were built, structures were painted and 

whitewashed, wire fence was installed, and on 

“April 30, 1893, the characteristic of the 

Loggerhead Key light was changed from fixed 

white to fixed white with a fixed red sector.”27

The implementation of red sector lighting was 

a navigational advancement for its time. A red 

pane of glass was installed on the side or sides 

of the lantern where the reefs or shoals were 

particularly dangerous. Shipmen knew not to 

 

27 Hurley, 45. 
20 Dry Tortugas Lighthouse Keeper’s Residence HSR 

Figure 12. 1887 survey of Dry Tortugas Light Station by A. C. Bell.
Historical Background and Context 

National Park Service 21 

 navigate directly into the red light for this 

would signal imminently dangerous waters. 

For most of the 1890s, once again Loggerhead 

and Garden keys were used as quarantine 

stations, this time for those suspected of being 

infected with small pox. Despite an order in 

1893 from the War Department to discontinue 

the quarantine stations, the two keys would 

serve this purpose until 1900. 

The Spanish American War 

In 1898, the United States entered into war 

with Spain over the liberation of Cuba. The 

Dry Tortugas served as a harbor and staging 

area for ships in the area. The most notable 

incident of the war occurred with the U.S.S. 

Maine. On January 24, 1898, the ship sailed to 

Havana and a few weeks later it suffered a 

massive explosion that killed 260 of its 350 

sailors and sank the battleship. At the time, the 

explosion was blamed on an underwater 

Spanish mine, and as a result, the U.S. declared 

war against Spain on April 21. The war cry 

“Remember the Maine!” stems from this 

incident. The war was relatively short-lived 

and a treaty ending the conflict was signed in 

December 1898. 

In 1976, a Navy panel concluded that the blast 

on the Maine was the result of an onboard fire 

in the coal storage area. It is possible that the 

fire may have originated while the ship was in 

the harbor at Garden Key. 

Bureau of Lighthouses 

With the turn of the century, came a change in 

the management of the Lighthouse Board. In 

1903, the Board was moved from the Treasury 

Department to the Department of Commerce. 

In 1910, it officially became known as the 

Bureau of Lighthouses. Congress intended to 

accomplish several objectives with this 

reorganization. First, it sought to demilitarize 

the lighthouse service. Both the Army and the 

Navy were not allowed a prominent role on 

the Board, the goal being to shed a civilian 

light on a primarily civilian service. Secondly, 

the reorganization allowed for an increase in 

districts to accommodate the growing number 

of light stations. In 1910, George R. Putnam 

was selected to lead the new Bureau of 

Lighthouses. Serving for 25 year, Putnam’s 

most notable contributions include the 

introduction of radio beacons as an added 

means of navigation, electrification of many 

light stations and a retirement system for field 

employees.28

The Carnegie Institution Marine 

Biology Laboratory 

In 1904, a portion of the northern end of 

Loggerhead Key was granted through a 

revocable lease, to the Carnegie Institute for 

the establishment of a research laboratory to 

study marine life in the Atlantic. The Institute 

declared in their 1904 Year Book the 

establishment of the Marine Biological 

Laboratory at the Dry Tortugas, under the 

direction of Alfred G. Mayor. 

Mayor was a Harvard educated biologist who 

initially studied butterfly pigmentation. 

However, due to a serious eye inflammation 

he was forced to pursue research that relied 

less on work with a microscope. Jellyfish 

offered the perfect specimen for him to study 

and he subsequently published a three volume 

work on the species. The Dry Tortugas offered 

an ideal location for collecting and observing 

jellyfish among other tropical plants and 

marine life. 

The laboratory complex was constructed 

between 1904 and 1906 and was comprised of: 

a main laboratory building and sleeping 

porch, a detached lab, a kitchen, a 

windmill for pumping salt water and air to 

aquariums, a dock, a shipways, two small 

outhouses and a cistern. The labs and 

outhouses were built in New York and 

shipped to Loggerhead for assembly, 

while the rest of the buildings were built 

on site. About 50 palm trees were planted 

around the lab to shade the buildings and 

provide hurricane protection. All the 

buildings, chemicals, lab glassware and 

furniture cost only $4,800. The lab’s 

research vessel was a 57-foot-long ketch, 

with a 20 horsepower auxiliary engine.29

A vast and diverse program of research was 

conducted at the laboratory. Some of the most 

notable accomplishments included groundbreaking research on coral reefs and 

 

28 Holland, 38. 

29 Hurley, 48. Carnegie Institute Yearbooks. 
22 Dry Tortugas Lighthouse Keeper’s Residence HSR 

Figure 13. Undated view of the Carnegie Institute’s Marine Biology Research Laboratory with the Dry 

Tortugas lighthouse in the distance. 

 mangrove communities, the establishment in 

1908, of the Dry Tortugas as a wildlife refuge 

for the sooty tern, and the first underwater 

photographs—both black and white and color 

were taken there. 

Although the Institute viewed Mayor as a 

promising individual, his selection of 

Loggerhead Key for the research laboratory 

was seen as a poor choice. It was too remote 

and difficult to access and receive support 

from the mainland. In addition, working 

around hurricane season left for a brief 

research period from May until July each year. 

Mayor had some aspirations to relocate the lab 

to Jamaica to create a truly international 

biological station, but he suffered from 

tuberculosis and in June of 1922, his body was 

found face down on the shore of Loggerhead 

Key. He was 54 years old. The coroner ruled 

that Mayor died of “heart-failure and general 

debility contingent upon his tubercular 

condition.”30 A plaque erected in his honor in 

 

30 Calder, Dale R. and Lester D. Stephens. Seafaring Scientist: 

Alfred Goldsborough Mayor, Pioneer in Marine Biology, 

1929 stands near the site of the former 

laboratory complex. 

The Carnegie lab survived through the Great 

Depression and several hurricanes until 1939, 

 when Carnegie President Vannevar Bush 

closed the laboratory. Reduced funding and a 

shift in philosophical focus from macrobiology to microbiology have been reasons 

stated for the closure.31 During the thirty-five 

years of laboratory operation, more than 140 

scientists visited and conducted research on, 

and in the waters surrounding Loggerhead 

Key. 

Early Twentieth Century 

Modernization 

The early part of the twentieth century not 

only included the restructuring of national 

lighthouse management and the birth of 

modern marine biology with the establishment 

of the Carnegie laboratory, but also ushered in 

 

Columbia, South Carolina: University of South Carolina Press, 

147. 

31 Hurley, 49. 
Historical Background and Context 

National Park Service 23 

Figure 14. Ca. 1925 Plan of the Dry Tortugas Light Station. 

modern technological advances at the Light 

Station. Radio beacons, electricity, concrete 

cisterns, a new lens and multiple construction 

projects were completed during this period. 

Two significant hurricanes during the 1910s, 

once again, caused serious damage to the Light 

Station and the laboratory complex. The 

hurricane of October 10, 1910, (hurricanes 

were not named until the 1950s) damaged the 

wharf, shattered panes of glass in the tower, 

and severely damaged the dormitory and blew 

the roof off the main building at the Carnegie 

laboratory complex. The machine shop was 

moved off its foundations nearly five feet. On 

September 8, 1916, Congress allotted $2,800 

and; 

a wrought-iron pile wharf with cast-iron 

caps and wooden girders, stringers, and 

decking was erected in place of the old 

wharf, which was destroyed. All work was 
24 Dry Tortugas Lighthouse Keeper’s Residence HSR 

Figure 15. Undated view of the Garden Key 

Keeper’s Residence with the iron lighthouse on 

bastion C in the distance. 

Figure 16. View of Dry Tortugas Keeper’s 

Residence shortly after completion. 

completed in May, 1917. Amount expended 

to June 30, 1917, $2,631.19.32 

As a result of damage sustained in the 1910 

hurricane, the original first-order lens was replaced 

with a second-order lens. 

A second hurricane hit the island on 

September 10, 1919, severely damaging the 

laboratory by washing away snail breeding 

cages and resulting in damage to all the 

buildings. 

Fort Jefferson experienced a massive fire in 

1912 that destroyed the Garden Key light 

keeper’s dwelling, as well as the fort’s 

barracks, kitchen and latrine. The keeper’s 

house was not rebuilt and some years later the 

harbor light was deemed unnecessary for 

navigational purposes and decommissioned. 

In 1921, the lighthouse on Loggerhead Key 

became the primary navigational beacon in the 

Dry Tortugas. 

Following the decommissioning of the light on 

Garden Key, the Bureau of Lighthouses took 

 

32 Ibid. 

several steps to upgrade and modernize the 

Light Station on Loggerhead Key. In 1922, a 

new dwelling for the primary keeper was 

constructed and two new concrete cisterns 

installed. Five years later when the original Oil 

House was converted to a radio beacon 

equipment room, it was connected to the 

tower by a reinforced concrete passageway. 

The marine radio beacon was installed in 1926 

to assist ship traffic and provide basic 

communication. The new technology offered 

a means of communicating with mariners 

about weather, operations, and navigational 

issues. The marine radio beacons were able to 

transmit communications to ships in storms 

when the lighthouse was difficult to see. 

The introduction of electricity to the island 

was another technological advancement that 

changed the way the Lighthouse and Light 

Station operated. Powered by generators, 

housed in a frame addition constructed on the 

south elevation of the former Oil House, the 

new electric light installed in the Lighthouse in 

1931 had 3,000,000 candle-power, making the 

Dry Tortugas light the brightest in America. 

Several mariners reported that they could see 

the light up to 52 miles away. Before 

electrification, the Lighthouse had a range of 

approximately 19 miles. The existing 

incandescent oil vapor lamp was kept as a 

secondary system. 

In 1935 Fort Jefferson was designated a 

National Monument by President Franklin 

Roosevelt and was transferred to the National 

Park Service. 

The U.S. Coast Guard 

In 1939, the duties of the Bureau of Lighthouse 

were amalgamated into the operation of the 

United States Coast Guard. Light keepers 

were given the choice of becoming petty 

officers or remaining as civilian employees. 

During World War II keepers were utilized as 

lookouts for German U-Boats in the Florida 

Straits. The threat of attack by enemy U-boats 

was real as twenty-four American ships were 

sunk by German submarines during the war. 

Coast Guard keepers also took part in beach 

patrols and at times had to rescue or recover 

victims of U-boat attacks. 
Historical Background and Context 

National Park Service 25 

Figure 17. Image taken from the top of the 

tower showing the burned remains of the 

original keeper’s dwelling. 

During the war, there was some debate as to 

whether the lighthouse lights should be 

extinguished or dimmed. Exposing ships to 

enemies was considered less of a danger than 

running aground, so the Coast Guard 

implemented “dim-out” policies in which the 

intensity of the lamps was turned down.33 

In March of 1945 a fire destroyed the original 

1858 keeper’s dwelling and damaged the 

adjacent kitchen building. As a result, the 

keeper’s dwelling had to be demolished to its 

foundations. A second fire in 1964 destroyed 

several of the abandoned Carnegie laboratory 

structures. 

Under management of the USCG the Dry 

Tortugas Light Station remained manned with 

a crew of from two, to as many as twelve 

personnel. From the mid-twentieth century to 

the 1990s, numerous projects were planned 

and implemented at the Station beyond the 

required routine maintenance and minor 

repairs that took up much of the time of those 

stationed on the island. A majority of the 

projects centered on upgrading and repairing 

the various systems that were critical to 

habitation of the island such as those that 

provided potable water, sanitary systems, and 

generation of electrical power. In 1967, 

extensive improvements were made to the 

tower including sandblasting the exterior and 

repainting the daymark. 

Projects in the 1970s focused on the 

installation of fuel and water tanks, upgrading 

electrical service and providing fire protection 

in the 1922 Keeper’s Residence or “barracks 

building” as it was referred to during this 

period. In 1975 during the construction of a 

new wharf on the eastern shore, a Seaman 

Apprentice, William H. Graves, was tragically 

killed. A small monument dedicated to 

Seaman Graves is located near the site of the 

accident. 

In 1984, the USCG commissioned National 

Park Service personnel to prepare a 

rehabilitation report and national register 

nomination for the Dry Tortugas Light Station 

property. This project was undertaken to 

document the history of the Light Station and 

to make recommendations for the appropriate 

 

33 Hurley, 57. 

repair of the historic lighthouse and support 

structures in advance of a planned automation 

and modernization program. The document 

included recommendations focused on repairs 

to the Lighthouse as well as both mortar and 

paint analysis. 

The following year an extensive program of 

repairs was completed on the Lighthouse, and 

in 1986, the USCG decommissioned the 

existing second-order bi-valve lens after 

aggregate from sand-blasting operations 

contaminated the mecury float mechanism. As 

a result the lens was no longer able to rotate 

and was replaced with an automated 24” 

Directional Code Beacon (DCB-24). The new 

lamp was programmed to create a flashing 

light every 20 seconds that could be seen up to 

24 miles away. The bivalve lens was removed 

and placed on display at the National Aids to 

Navigation School in Yorktown, Virginia 

where it remains today.34 

The National Park Service 

Following automation of the Lighthouse optic 

in 1986 the USCG continued to be challenged 

 

34 Dean, 99. 
26 Dry Tortugas Lighthouse Keeper’s Residence HSR 

by mounting deferred maintenance and 

limited funding for repair or capital 

improvements. In an effort to reduce their 

burden, consideration was given to 

demolishing several non-essential structures 

including the boat house and original kitchen 

building. In addition, advancements in the 

Long Range Navigation (LORAN) system and 

GPS (Global Positioning System) technology, 

as well as the expanded use of Satellite 

Navigation (SATNAV) resulted in diminishing 

reliance by mariners on visual aids such as 

lighthouses and beacons. 

About the same time, the National Park 

Service, and at least two other groups, 

expressed interest in taking over management 

of Loggerhead Key and the Light Station 

property from the USCG. The other groups 

vying for the property included the Key West 

Ports and Transportation Authority who was 

interested in establishing a marine hatchery 

and science camp on the island, and the Key 

West Art and Historical Society who 

expressed an interest in managing the 

lighthouse, but had not submitted a formal 

proposal. 

In 1991, the Coast Guard determined that the 

National Park Service presented the most 

viable proposal and several meetings were 

held between the two entities to evaluate the 

condition of the existing resources and to 

discuss the logistics of a transfer. Negotiations 

focused on resolution of several utility issues 

regarding the electrical generators and septic 

system and also a requirement for the USCG 

to remove all hazardous materials from the 

island as a condition of transfer. Despite their 

desire to divest themselves of the Light Station 

completely, the USCG would continue to 

maintain the light as an active aid to navigation 

and provide logistical support to the Park 

Service as part of the agreement. Transfer of 

the light station also provided opportunity for 

the USCG to eliminate permanent staff on the 

island and limit its obligation to routine site 

visits to maintain the optic. Establishment of 

Dry Tortugas National Park the following year 

provided the ideal mechanism for formally 

transferring Loggerhead Key and the Light 

Station to the National Park Service. 

Dry Tortugas National Park was created in 

1992 to “preserve and protect for the 

education, inspiration, and enjoyment of 

present and future generations nationally 

significant natural, historic, scenic, marine and 

scientific values in South Florida.” The Park 

boundaries established at the time 

encompassed all of the seven small islands that 

make up the Dry Tortugas as well as the coral 

reefs, shoals and waters within an 

approximately 100 square-mile area. As part of 

the enabling legislation for the Park, the USCG 

lands, including all of Loggerhead Key were 

formally transferred from the USCG to the 

National Park Service. The establishment of 

Dry Tortugas National Park also resulted in 

the Light Station resources being listed on the 

National Register of Historic Places. 

Through its Volunteers-In-Parks (VIP) 

program, the Park Service has been able to 

maintain a consistent presence on Loggerhead 

Key for much of the last two decades. The 

volunteers, who stay on the island for one to 

several months at a time, are housed in the 

former kitchen building and perform limited 

repair and maintenance of the resources. 

More importantly their presence provides a 

level of security for the island that serves as a 

deterrent to those that may seek to damage or 

cause harm to cultural or natural resources. 

Since the National Park Service assumed 

management of the Light Station they have 

had the additional challenge of dealing with 

Cuban refugees making landfall at Loggerhead 

Key. The Dry Tortugas have become a primary 

landing point for the refugees due to their 

proximity to Cuba and remote location. 

Since adoption of the “wet foot/dry foot” 

policy in the mid-1990s, the influx of refugees 

has been steady. The wet foot/dry foot policy 

generally states that if a refugee is able to make 

landfall on U.S. soil they will be allowed to stay 

and can pursue citizenship, on the other hand, 

if they are intercepted in the waters between 

Cuba and the United States, they will be sent 

back to Cuba or to a third country. 

Generally arriving at night, during periods of 

calm weather, the refugees cross the open 

waters between the two countries in makeshift boats referred to as “chugs.” These chugs 

accumulate on the keys and intermittently 

have to be removed to the mainland for 

disposal. 
Historical Background and Context 

National Park Service 27 

Figure 18. Chug used by Cuban refugees to land 

at Loggerhead Key in 2008. 

Figure 19. Graffiti left by Cuban refugees on wall

of Boathouse. 

Figure 20. Aerial view of Loggerhead Key 

showing density of Australian Pine growth prior 

to de-vegetation project. 

After the Mariel Boatlift in 1980, the numbers 

of Cuban refugees attempting to enter the 

United States peaked again in 1994 and 2005. 

Refugees that make landfall within the Park 

are temporarily detained by the National Park 

Service until USCG officials can transfer them 

to the mainland for processing. Historic 

resources, primarily the Boathouse on 

Loggerhead Key and the casemates within 

Fort Jefferson on Garden Key, are 

occasionally used to temporarily house landed 

refugees. In recent years the USCG has 

increased its patrols in the waters around the 

Park reducing the number of refugees making 

landfall on the Keys. 

The National Park Service has also recently 

completed an extensive landscape restoration 

program to remove the Australian Pine and 

other exotic plants from Loggerhead Key. 

These invasive species were introduced by 

Carnegie Institute personnel during the first 

half of the twentieth century dramatically 

changing the landscape character of the island. 

The program has been successful in removing 

the trees and returning the island to its preCarnegie appearance. 

With the exception of the Lighthouse which 

continues to function as an active aid to 

navigation, the resources of the Dry Tortugas 

Light Station are primarily used for housing 

and also to shelter critical components of the 

island’s utility systems. Volunteers from the 

VIP program occupy the former original 

kitchen building for most of the year and the 

1922 Keeper’s Residence is reserved for 

intermittent use by National Park Service 

personnel, researchers or contractors. The 

USCG also maintains a room in the Keeper’s 

Residence for its use during routine visits to 

service the light. Visitation to the Park is 

limited by the Park’s General Management 

Plan Amendment currently limits the numbers 

of visitors allowed on the island to 24. It also 

establishes permissible activities allowed on 

the island which include hiking, picnicking 

and exploring. The GMPA currently restricts 

access to the Lighthouse and Light Station 

buildings by the visiting public until such time 

as they can be made safe for this level of use.
28 Dry Tortugas Lighthouse Keeper’s Residence HSR 
National Park Service 29 

Figure 21: Rear elevation of original 1858 Keeper’s 

Dwelling. 

Chronology of 

Development and Use 

Historical research conducted in the federal 

records of the Lighthouse Service, Coast Guard, 

and National Park Service and investigation of 

the existing building during the course of the 

present study provide an understanding of the 

broad patterns of development and use of the 

Keeper’s Residence at the Dry Tortugas Light 

Station. 

Constructed in 1922-23, the Keeper’s Residence 

was built to provide much-needed residential 

living space for the principal lighthouse keeper 

and his family during a period of modernizing 

the Light Station. The residence underwent 

several changes during the period of Coast 

Guard oversight of the Light Station. The floor 

plan was altered and plumbing system updated 

in the early 1950’s, including the addition of a 

water line from an elevated tower near the 

Lighthouse and installation of a hot water heater 

flue, bathroom fixtures and a kitchen sink. A fire 

detection system was added in the early 1970’s 

and the interior floor plan altered c. 1982. Major 

repairs took place in 1985, including additional 

floor plan changes, rewiring and installation of 

new fixtures and outlets, replacement of eave 

fascia & soffit and gutters, as well as installation 

of new flooring, gypsum board over the walls 

and ceilings, and new baseboards. 

Additional changes have occurred since the 

National Park Service assumed management of 

the Station in 1992. The installation of 

centralized air conditioning, high efficiency 

appliances, and attic insulation occurred in 2002 

as part of a larger project to eliminate 

environmental problems associated with the use 

of diesel fuel on the island. The windows were 

replaced with Pella architectural series 

thermopane windows in 2003. Although dates of 

installation are not known, evidence of 

additional alterations to the building include the 

installation of a fiberglass shower and new 

vanity unit in the bathroom as well as the 

existing composition asphalt shingle roof and 

metal hurricane shutters on the exterior of the 

building. 

Although the Keeper’s Residence has undergone 

these changes over time, it has retained a 

substantial amount of its historic materials and 

continues to express a majority of its historic 

residential character. 

Original Construction

There were three keepers – the principal keeper 

and two assistants -- and their respective families 

residing at the Dry Tortugas Light Station by 

January of 1917. All three keepers and their 

family members lived in the original 1858 twostory brick keeper’s dwelling. 35

The earliest correspondence regarding the need 

for a new Keeper’s Residence began in 1916 with 

a letter from the Office of Lighthouse Inspector 

 

35 Department of Commerce, Recommendation for Repairing Aids 

to Navigation, January 3, 1917. Record Group 26: National 

Archives, Washington, DC. 
30 Dry Tortugas Lighthouse HSR 

to the Commissioner of Lighthouses in 

Washington. This letter stated that “the only 

dwelling that is necessary for light keepers in this 

district at the present time is one for the Keeper 

of Dry Tortugas Light Station, Fla.” The letter 

went on to state that “it should be a substantially 

constructed reinforced concrete or brick 

structure in order to safely withstand the 

destructive tropical storms that frequently visit 

that locality.” 36

 

36 Correspondence from Office of Lighthouse Inspector to 

Commissioner of Lighthouses, December 5, 1916. Record Group 

26: National Archives, Washington, DC. 

Correspondence from the Lighthouse Inspector 

to the Lighthouse Commissioner in early 1917 

indicates that all three keepers and their families 

were living in the original dwelling. These 

cramped quarters were considered 

inappropriate by the lighthouse district 

superintendant: 

All three keepers and their respective families 

at present live in the same dwelling, a two-story 

brick eight-room house with slate roof. The 

two assistant keepers and their families occupy 

the lower floor, each having one large room 

and one small room. The Keeper and family 

occupy the upper story, which has four rooms, 

two large and two small. Each keeper has a 

kitchen in a detached building, and there are 

two wash houses, also detached. The quarters 

are entirely inadequate for the number of 

persons to be housed, and are very 

inconvenient. The crowding of three families 

into the same building, which is not designed 

with a view of keeping them separate, leads to 

ill-feeling and quarrelling and encourages 

improper conduct. 37

Early Plan Development 

George R. Putnam, first Commissioner of the 

newly organized Bureau of Lighthouses, 

endorsed the idea of constructing additional 

quarters at the Dry Tortugas Light Station. 

The initial intent of the Lighthouse Board was to 

build a fireproof concrete building to house 

multiple keepers and their families that was 

similar in appearance to the original keeper’s 

dwelling. Schematic drawings and specifications 

for a new dwelling were published by the 

Lighthouse Service in late 1916. These plans 

illustrate a structure very much like the original 

dwelling, but instead of the two room over two 

room plan with central hall and stair of the 

original dwelling, the plans for the new 

residence reflected a four room over four room 

layout. The dining room, kitchen, keeper’s office 

and living room are shown on the first floor and 

four bedrooms with one bathroom on the 

second floor. The plans were prepared by the 

Office of the Lighthouse Inspector-Seventh 

District. 

 

37 Department of Commerce, Recommendation for Repairing Aids 

to Navigation, January 3, 1917. Record Group 26: National 

Archives, Washington, DC. 

Figure 22: Front elevation of proposed new wood 

frame Keeper’s Residence (1916). 

Figure 23: First floor plan of proposed new wood 

frame Keeper’s Residence (1916). 
Chronology of Development and Use 

National Park Service 31 

Figure 24: Revised front elevation of proposed new 

concrete Keeper’s Residence (1917). 

Figure 25: Revised first floor plan of proposed new 

concrete Keeper’s Residence (1917). 

Correspondence between the Lighthouse 

Service and the Seventh District office resulted 

in several plan changes. It was determined that 

the structure should be constructed fully of 

concrete. The first floor walls were to be 8” thick 

poured-in-place concrete and the second floor 

walls 6” thick. The interior walls were to be 

“ribbed metal lath plastered with cement”. 38 

The project budget was set at $6,500.00. 

Over the next several years the drawings and 

specifications were further developed. Shortly 

after comments were received on the 1916 set of 

plans, a second set was published in 1917 that 

incorporated the changes requested. Concrete 

was used as a building material based on its fire 

resistance. Testing of sand samples from the 

island indicated that with the proper aggregate, 

it could be used for concrete foundations and 

posts. 

By March of 1920, the wall design changed from 

poured-in-place concrete to hollow concrete 

blocks. 39 Anticipating that construction costs 

would exceed the budget, value engineering 

strategies were suggested by W.W. Demerritt, 

the Seventh District Superintendent of 

Lighthouses, in a letter to the Commissioner of 

Bureau of Lighthouses: 

In view of the comparatively small 

appropriation for dwelling at the present high 

prices, in order to avoid any possibility of over 

running the allotment, it is proposed to 

undertake these works in the order mentioned 

below until funds are exhausted, the other 

works to be finished with funds from General 

Expenses, when available: Dwelling; Cistern; 

Plumbing, including concrete water tower; 

Concrete walks; and Fence. 40

In June of the same year, there is further 

correspondence that most of the plumbing — 

including fixtures and piping — should be 

removed from the project to help bring the cost 

down. 41 By August 1920, Superintendent 

 

38 Comments on preliminary plans for Keeper’s Dwelling at Dry 

Tortugas Lt. Sta., January 3, 1917. Record Group 26: National 

Archives, Washington, DC. 

39 Department of Commerce, Dry Tortugas, Fla., Keeper’s 

Dwelling, March 20, 1920. Record Group 26: National Archives, 

Washington, DC. 

40 Superintendent of Lighthouses to Commissioner of Lighthouses, 

March 31, 1920. Record Group 26: National Archives, Washington, 

DC. 

41 Correspondence from Acting Commissioner of Lighthouses to 

Superintendent of Lighthouses, June 23, 1920; August 11, 1920. 

Record Group 26: National Archives, Washington, DC. 

Demerritt appears willing to put the project on 

hold to request additional funding at a later date. 

It appears that based on the funding shortage 

however, the original scope of constructing a 

residence to house multiple keepers and family 

members was reduced to building a smaller 

building to house only the principal keeper and 

his family. A subsequent set of undated plans 

was developed based on this change to a singlefamily residential use. The plans are for a small, 

square concrete block house with two 

bedrooms, a dining room, bathroom, pantry and 

kitchen. 
32 Dry Tortugas Lighthouse HSR 

Figure 26: Undated front & rear elevation of proposed 

new single story concrete Keeper’s Residence. 

Figure 27: Undated floor plan of proposed new single 

story concrete Keeper’s Residence. 

These plans for a smaller residence did not meet 

approval with Superintendent Demerritt. In 

correspondence relating to this set of plans, the 

superintendent commented: 

After comparing the dwelling shown on 

attached blueprints with other dwellings for 

keepers in this district, it is the opinion of 

this office that it is too small for the purpose 

intended and does not compare favorably 

with existing accommodations at Dry 

Tortugas L.S., nor even with the dwellings 

furnished some assistant keepers of the 

district. The rooms are too small for comfort 

in this climate, and there are not enough 

rooms for some of our keepers with large 

families. The two bedrooms and the kitchen 

should be 1-1/2’ to 3’ larger in length and in 

width, and an additional room should be 

furnished, but this latter could be made to the 

building in the rear of the kitchen with funds 

from General Expenses, the addition to be 

used as a kitchen and the present kitchen as a 

dining room. If this would not be permissible, 

it would be to the ultimate interest of the 

Service, and to the keepers of the station, to 

ask for additional appropriation and wait until 

sufficient funds were authorized for a more 

suitable dwelling for the Keeper at this, the 

most important and finest land station in the 

district. 42

The drawings that Demerritt refers to were 

likely a set of small dwelling plans archived with 

the remainder of drawings from this period in 

the National Archives. The plans were never 

dated or signed as approved but they fit as a 

logical link in the evolution of the design from 

the initial large concrete dwelling to the brick 

bungalow that was ultimately built. The 

drawings show the concrete block wall 

construction intended for the larger dwelling 

while the plan layout resembles a smaller version 

of what was actually built. 

Demerritt’s grievances may be easily inferred 

from the concrete dwelling plans and 

subsequently resolved with the new plans for the 

brick bungalow. As constructed, the design for 

the new Keeper’s Residence appears to have 

incorporated Demerritt’s comments – the 

bedrooms were two feet wider than originally 

planned and a dining room was added to the 

building. 

While Demerritt was voicing his concern over 

the plans for the Keeper’s Residence, the 

Lighthouse Service issued an advertisement for 

bid (No.3344) in August 1920. The specifications 

associated with this bid indicate the mixes for 

 

42 Correspondence from Superintendent of Lighthouses to 

Commissioner of Lighthouses, August 11, 1920. Record Group 26: 

National Archives, Washington, DC. 
Chronology of Development and Use 

National Park Service 33 

the concrete blocks, cement, sand, mixing and 

placing instructions, mortar mix, and stucco to 

be used on the concrete blocks. Plaster is 

specified for interior walls. The framing lumber 

was to be long-leaf yellow pine as were the floor 

and subfloor. The subfloor material was to be 7⁄8” 

x 6” boards laid diagonally and the floor material 

7⁄8” x 3- 1⁄2” prime grade flooring. The ceiling 

framing was to be long leaf yellow pine of 

various sizes. The interior mouldings were 

specified to be cypress. Shelving was specified 

for the pantry and the kitchen was to receive a 

china cabinet. The plumbing specification is set 

up so that the contractor is to rough in all the 

connections and extend pipes beyond 

foundations; however, the plumbing fixtures are 

specifically called out as a separate line item. 43

No bids are available from this time period, but 

it appears the price may have exceeded the 

appropriated limit. Correspondence alludes to 

internal estimates that imply the design 

continued to exceed the stated appropriation. By 

August 18, 1920, the Bureau of Lighthouses had 

agreed with Demerritt and deferred further 

action regarding the construction of a new 

residence at Dry Tortugas “until such time as the 

allotment can be adequately increased, or until 

you are otherwise advised in this matter.” 44

The Keeper’s Residence is Funded 

Over a year later there is evidence of a shift in 

construction from concrete to load-bearing 

brick masonry. The Lighthouse Service prepared 

a cost estimate in December 1921 with face brick 

and common brick “to construct a brick 

dwelling for keeper.” 45 Despite allusions to the 

escalated cost of the residence, every available 

estimate for the Keeper’s Residence — whether 

it be concrete or brick — from the period of 

1916 to 1921 totals $6,500. 

In addition to the cost estimate, the 1922 fiscal 

year appropriations request signals a material 

change in construction to brick as 

Superintendent Demerritt described the 

 

43 Specifications for Single Dwelling for Keeper. Record Group 26: 

National Archives, Washington, DC. 

44 Bureau of Lighthouses to Superintendent of Lighthouses, 

August 18, 1920. Record Group 26: National Archives, 

Washington, DC. 

45 Estimate of Cost of Proposed Works, Lighthouse Service, 

Department of Commerce, December 12, 1921. Record Group 26: 

National Archives, Washington, DC. 

appropriation for a “brick dwelling for the 

keeper.” In the “Description of Need” section of 

the appropriations request, Demerritt indicates a 

renewed need for additional living quarters as 

the number of keepers present at the Light 

Station had increased from three to four since 

the last appropriations request. 

 

All four keepers and their respective families 

live in the same dwelling, a two story brick 

eight-room house, four of the rooms are 

about 8’ x 10’. The quarters are absolutely 

inadequate for the number to be housed, and 

now there are four, hence the urgent 

necessity for additional accommodations for 

these employees. The overcrowding of four 

families into the same building which is not 

designed with a view to keeping them 

separate and according them a reasonable 

degree of privacy, leads to ill-feeling and 

quarreling and encourages improper 

conduct. It is recommended that funds be 

reallocated in order that this urgent work 

can be immediately undertaken. 46

The Bureau of Lighthouses approved the 

appropriations request on December 24, 1921. 

Demerritt then requested that an additional 

appropriation of $9,200 be issued from the 

General Expenses, Lighthouse Service for the 

1922 and 1923 fiscal years. The funding strategy 

that he initially suggested in 1920 materialized 

with a request: 

To afford proper living conditions for the 

keepers and their families the existing 

building are to be rearranged, remodeled 

and fitted with more modern 

accommodations. A supply of running water 

will be furnished to all dwellings while 

sanitary sewers will be constructed to serve 

them. A systematic arrangement of walks is 

desirable to facilitate work and improve the 

general appearance of these grounds. 

Additional cistern capacity is desirable to 

conserve the rain water supplied from the 

available roof areas. 47

 

46 Request for Appropriations (Form 80), Superintendent of Light 

Houses to Bureau of Lighthouses, December 12, 1921. Record 

Group 26: National Archives, Washington, DC. 

47 Recommendation as to Aids to Navigation, Superintendent of 

Light Houses to Commissioner of Lighthouses, April 28, 1922. 

Record Group 26: National Archives, Washington, DC. 
34 Dry Tortugas Lighthouse HSR 

It appears from this sequence of appropriations 

requests that the Keeper’s Residence was built 

without plumbing and that this later 

appropriation provided those systems. 

Construction 

After evolving through these design iterations, 

the Keeper’s Residence was constructed with a 

configuration smaller than originally planned. It 

is assumed that Keeper Charles H. Johnson, 

appointed in 1919, and his family occupied the 

house upon its completion in 1923. 

An undated site plan of the Light Station shows 

the proposed dwelling for keeper to be located 

approximately the same distance from the 

Lighthouse as the 1858 keeper’s dwelling but on 

the northeast side of the station. 

In plan the new structure was laid out parallel to 

the existing keeper’s dwelling so that the main 

entrance and porches of both buildings faced 

the same eastern direction. 

The bungalow building type with Craftsmen 

elements was typical of residential bungalows 

being constructed throughout America’s 

suburbs during this period. The completed 

building is a single story brick building with a 

hipped roof with a slight flair at the roof edge. As 

constructed, the residence did not resemble the 

first drawings for the Keeper’s Residence, but 

did resemble the small concrete dwelling shown 

in Figures 25 and 26. The plan, roughly 50’ x 35’, 

consisted of front steps centered on a central 

door. 

The original floor plan in the 1921 architectural 

plans was typical of bungalows of this period. 

The original plans show the Living Room, 

Dining Room, Pantry and Kitchen on the 

southwest side of the building and the Porch, 

Bedroom, Bathroom and another Bedroom on 

the northeast side. The Living Room and Dining 

Room were separated by a wall with a cased 

opening. A door on the northwest side of the 

rear wall of the Dining Room led to the Pantry. A 

small vestibule was directly opposite the Pantry 

and led to a bathroom between the bedrooms. 

The front bedroom had direct access to the front 

porch through door D2. 48 

 

48 Architectural Drawing, “Floor Plan for Keeper’s Brick Dwelling,” 

December 2, 1921. Record Group 26: National Archives, 

Washington, DC. 

Figure 28: Early view of Keeper’s Residence. 
Chronology of Development and Use 

National Park Service 35 

Figure 29: Undated Light Station Site Plan – note proposed site of new Keeper’s Residence to the northeast 

of the lighthouse. 
36 Dry Tortugas Lighthouse HSR 

The 1920 construction specifications and 1921 

architectural plans indicate that 14 of the 

windows were six-over-six double-hung wood 

windows with sash and frames constructed of 

yellow pine and a single casement window of 

eight-light casements located on the northwest 

elevation. The specifications and historic images 

further indicate that the windows of the 

Keeper’s Residence included operable wood 

shutters. Some shutters were Bahama-style 

shutters that were hinged at the window head 

and opened out from the sill while others were 

standard shutters hinged along the window 

jambs that opened flat again the outside walls. 

The specifications and historic images indicate 

that the window sash and frames were painted 

white and the shutters green. 49

 

49 “Specifications for a Single Dwelling for Keeper at Dry 

Tortugas Lightstation, Florida,” August 10, 1920. Record Group 

26: National Archives, Washington, DC, 7. 

The architectural plans indicate that the original 

roofing and sheathing for the Keeper’s 

Residence were hexagonal asbestos shingles and 

tongue and groove wood, respectfully. The 

Items, Quantities, and Unit Prices in the 

December 12, 1921 Estimate of Cost of Proposed 

Works includes “14 squares” of “hex asbestos 

shingles at $19 per square”. In addition, 

architectural drawings dated July 19, 1985 

indicate that the roofing was asbestos shingles 

and sheathing was 1” x 4” tongue and groove 

wood at that time. 

The plans also indicate that the building was 

intended to have gutters and downspouts, with 

the downspouts located in the middle of the 

northwest elevation and at the juncture of the 

front porch and masonry wall on the northeast 

and southwest elevations. Historic photographs 

dating from the period of construction indicate 

that the house originally had fascia-hung gutters 

and downspouts at these locations. The 

Figure 30: Floor plan of Keeper’s Residence as it was constructed (1921). 
Chronology of Development and Use 

National Park Service 37 

specifications indicate that gutters and leaders 

shall be No. 26 gage “Armco” iron or equal, 

heavily galvanized. Leaders shall be 4 inches in 

diameter, joints riveted and well soldered. 

Leaders shall be well supported and secured to 

swelling with substantial galvanized iron 

fittings.” 

The specifications also outlined the 

characteristics of interior moldings, including 

that all interior trim would be of cypress; 

window and door trim and base board would be 

of plane section with rounded edge or edges; 

molding at intersection of ceiling and side walls 

would be of a plain strip, 3⁄4 x 3 inches with lower 

edge rounded, and a 1 inch quarter round 

molding; door and window casings and apron 

would be approximately 7/8 x 41⁄4 inches and 

baseboard 7/8 x 71⁄2 inches; and joint at base and 

floor would be finished with 1 inch quarter 

round molding. 50

 

50 “Ibid,,4. 

The Keeper’s Residence Undergoes 

Gradual Changes 

The Coast Guard and National Park Service 

were able to provide drawings of projects that 

were completed at the Keeper’s Residence over 

time. These drawings give us a glimpse into the 

types and timing of changes that took place to 

the building. 

The U.S. Bureau of Lighthouses was 

amalgamated into the operations of the U.S. 

Coast Guard in 1939. After the Coast Guard 

acquired oversight of the Light Station, the 

function of the Keeper’s Residence changed 

from a single family dwelling to more of a 

bunkhouse as crews of officers began manning 

the island. The number of officers stationed 

increased to between seven and twelve per 

month, but family members were not allowed to 

live on the island during this period. 

Before the 1950s, there appear to have been no 

significant changes to the building. The wood 

elements of the house were certainly repainted 

during this early period, probably maintaining 

 

Figure 31: Early view of Keeper’s Residence 
38 Dry Tortugas Lighthouse HSR 

Figure 32: “Quarters Building” from 1951 Improvements to Sanitary Facilities (dated 8/27/51). 

 

the original colors, which were described as 

white trim with green blinds. 

In 1951 the Keeper’s Residence was renovated 

under the scope of a project entitled 

Improvements to Sanitary Facilities. A 1-1/2” 

water line was planned to run from elevated 

water tanks near the Lighthouse to the 

northeastern elevation of the residence. The 

project included removing and replacing all 

ceilings with masonite and providing new ceiling 

fixtures. There is currently no physical evidence 

that masonite was installed, though it could have 

been removed at a later date. The kitchen, dining 

room, pantry and hall were to receive 

“greasproof [sic] asphalt tile laid over #15 felt.” 

51 Windows or doors that were termite infested 

were to be repaired or replaced. The exterior 

elements — gutters, downspouts, soffits and roof 

shingles were to be repaired as necessary. The 

drawings instruct that wiring and plumbing 

should be “renewed where necessary.” 52 A new 

 

51 Architectural Drawing, “Improvements to Sanitary Facilities, Dry 

Tortugas Light Station, Loggerhead Key, Florida,” August 27, 

1951, Archives, United States Coast Guard 7th District, Miami, FL. 52 Ibid. 

sink was to be installed in the kitchen and a 

water heater flue installed through the roof. A 

new tile floor and wainscot was to be installed in 

the bathroom and new plumbing fixtures added. 

A lead pan was to be installed under the shower. 

In addition, two changes to the floor plan were 

implemented at this time. A portion of the wall 

between the kitchen and original bedroom (now 

dining room) at the northeast end (rear) of 

residence was removed to create a combination 

kitchen/dining room and a door opening 

between the bathroom and rear bedroom (now 

dining room) was enclosed to create a square 

hall. 

Changes in the 1960s and 1970s 

Air conditioning was installed in the Keeper’s 

Residence in 1969. The project included 

instillation of five window units (1-8,000 BTU 

and 4-13,000 BTU), a ceiling exhaust fan for the 

kitchen and glass fiber insulation in the attic. 53

 

 

53 Architectural Drawing, “Barracks Building Air Conditioning, Dry 

Tortugas Light Station, Loggerhead Key, Florida,” April 10, 1969, 

Archives, United States Coast Guard 7th District, Miami, FL. 
Chronology of Development and Use 

National Park Service 39 

Figure 33: Changes in floor plan following 1951 project Improvements to Sanitary Facilities. 

 

Based on a review of available architectural 

drawings, it appears that a lay-in suspended 

acoustical tile ceiling was installed on the 

interior sometime between 1969 and 1989. The 

original double-hung windows were also 

removed during this period, and replaced with 

awning and jalousie windows. It is likely that the 

original Bahamian style exterior shutters were 

removed when the original windows were 

replaced. 

A fire detection system was installed in 1971 in 

the Keeper’s Residence. Surface mounted 

ionization detectors were installed in the front 

rooms and thermal detectors were placed in the 

kitchen, dining, pantry and hallway. A control 

panel was located in the pantry and three 

manual switches installed — one each in the 

private bedroom, living room and kitchen. 54 

Modifications in the Late 1980s 

Additional changes to the Keeper’s Residence 

took place in the mid-to-late 1980s. The interior 

 

54 Architectural Drawing, “Barracks Building Fire Detection 

System, Dry Tortugas Light Station, Loggerhead Key, Florida,” 

April 6, 1971, Archives, United States Coast Guard 7th District, 

Miami, FL. 

floor plan was altered c. 1982 by adding interior 

walls to separate the front room into two 

separate spaces with a corridor between them. 

Drawings dated August 22, 1985 illustrate asbuilt conditions for a rehabilitated Keeper’s 

Residence and these new walls are shown as 

“existing work to be removed.”

The floor plan was altered again c. 1989 based 

on “as-built” drawings dating from that year. 

The walls added in the early 1980s are shown as 

removed, and a new wall was provided to create 

a second private bedroom in what was originally 

the dining room —subsequently shown in later 

plans as the berthing room. 

The new wall formed a hall that leads from the 

Living Room at the front of the house to the 

Kitchen/Dining Room at the rear, with a 

bedroom and laundry room on the southwest 

side and the front bedroom, vestibule, and 

bathroom along the northeast side of the house. 

The existing plan configuration is different from 

the original layout, but offers roughly the same 

 
40 Dry Tortugas Lighthouse HSR 

Figure 34: Changes in floor plan following 1951 project Improvements to Sanitary Facilities. 

 

type and quantity of spaces as originally 

planned. 55 

The drawing at right (Figure 38) is a composite 

showing the evolution of changes to the 

Keeper’s Residence floor plan over time. 

The house was completely rewired during this 

period. Except for the main service to the 

distribution panel, all existing wiring was 

removed and replaced with non-metallic 

conduit (NMC). Existing fixtures and outlets 

were removed and replaced with fluorescent 

light fixtures in the house and incandescent 

fixtures on the porches. Both the fire alarm and 

electrical panels were replaced. 56

 

55 Architectural Drawing, “Crew’s Quarters Floor Plan, Dry 

Tortugas Light Station Rehabilitation, Dry Tortugas Light Station, 

Loggerhead Key, Florida,” August 22, 1989, Archives, United 

States Coast Guard 7th District, Miami, FL. 56 Architectural Drawing, “Electrical Plans, Dry Tortugas Light 

Station, Loggerhead Key, Florida,” August 22, 1989, Archives, 

United States Coast Guard 7th District, Miami, FL. 

Also in the late 1980s in a letter from the 

Commander of Coast Guard Group Key West to 

the Commander of the Seventh Coast Guard 

District, the following observations were made, 

“failure of the mortar in the masonry at the main 

house is contributing to the collapse of both the 

front and rear porches” and “the rear area of the 

main house is infested with termites and the 

entire structure is overdue for tenting.” 57 Based 

on information in a “Dwelling/Lighthouse 

Condition Survey” for the Crew’s Quarters 

completed in November 1991, the structural 

issues with the front and back porch foundation 

walls were corrected in 1989. 58 

 

 

57 Letter, Commander of Coast Guard Group Key West to 

Commander of Seventh Coast Guard District, May 4, 1989; 

Archives: National Park Service, Everglades National Park, 

Homestead, FL. 

58 Dwelling/Lighthouse Condition Survey of Crew’s Quarters, 

November 10, 1991; Archives: National Park Service, Everglades 

National Park, Homestead, FL. 
Chronology of Development and Use 

National Park Service 41 

Figure 35: Barracks Building Fire Detection System from 1969 (dated 6 April ’71). 

In addition, the following changes to the 

exterior and interior of the building took place 

during the late 1980’s. 

 Original eave fascia and soffit 

components removed to repair rafters 

and joist tails – replaced with new 1⁄2” x 

14” plywood soffit, 4” continuous fiber 

glass screen, quarter round wood 

molding, and 1” x 8” wood fascia. 

 New PVC gutters installed at eave 

 Existing 1” x 12” cornice fascia retained 

and 7/8” x 33⁄4” molding removed. 

 Exterior side door at rear of residence 

replaced. 

 Vinyl asbestos tile (VAT) installed in 

Rooms front room, hallway, pantry, 

bathroom, and kitchen/dining room. 

 Half-inch gypsum wall board and 1” x 

2” furring strips installed over plaster 

walls. 

 Removal of existing lay-in suspended 

ceiling revealing historic crown 

molding concealed within and 

installation of gypsum board over the 

original pine ceilings. 

 Original 7/8” x 71⁄2” base board removed 

and new 3⁄4” x 4” wood baseboard and 
42 Dry Tortugas Lighthouse HSR 

shoe molding installed throughout the 

residence. 59

National Park Service Modifications 

There have been several changes to the Keeper’s 

Residence since the NPS acquired oversight of 

the station in 1992. In 2002, power on the island 

was converted from the diesel powered 

generators to photovoltaic electric generation 

and battery storage. Part of the project included 

equipping the Keeper’s Residence with high 

efficiency appliances, installing a centralized air 

handling unit and adding insulation. The ceiling 

was dropped above the hallway to accommodate 

the new unit and the compressors are visible on 

the exterior of the residence. 60

Soon thereafter, in 2003, the existing windows 

were replaced with Pella architectural series 

thermo pane windows because the existing 

windows would not close and were not keeping 

the elements out of the structure. The six-oversix pane sash of the new windows matches the 

pane configuration of the original windows. The 

PMIS 48292 with the cost of $22,500 notes that 

the replacement windows were approved by the 

National Park Service Southeast Regional Office 

and the Florida State Historic Preservation 

Officer. 61

Although dates of installation are not known, 

evidence of additional alterations to the 

Keeper’s Residence includes the installation of a 

 

59 Architectural Drawing, “Crew’s Quarters Floor Plan, Dry 

Tortugas Light Station Rehabilitation, Dry Tortugas Light Station, 

Loggerhead Key, Florida,” August 22, 1989, Archives, United 

States Coast Guard 7th District, Miami, FL. 60 “Convert From Diesel to Photo-Voltaic Electric Generation - 

Loggerhead Key, PMIS 71050,” April 23, 2008 (date of last 

update), National Park Service, Southeast Regional Office, 

Atlanta, GA. 

61 “Replace Windows – Lighthouse Keepers Quarters - Loggerhead 

Key, PMIS 48292,” September 13, 2006 (date of last update), 

National Park Service, Southeast Regional Office, Atlanta, GA. 

fiberglass shower and sink and cabinet unit in 

the bathroom and metal storm shutters and 

tracks at window exteriors. 

Currently, the Keeper’s Residence consists of 

the living room; central hallway; bedroom added 

in the original dining room; Coast Guard office 

located in the former front bedroom; laundry 

room added in the original pantry; bathroom; 

and kitchen/dining room (at the original rear 

bedroom). 

The building is currently used to provide 

housing for contractors and visitors to the Light 

Station. The living room is used as general living 

space and bunk room. The pantry and vestibule 

have been modified to accommodate electrical 

panels, a washer/dryer unit and the dropped 

ceiling for the HVAC duct work. 

Considerable thought and planning went into 

building a new Keeper’s Residence on 

Loggerhead Key. From 1916 to 1921 the plans 

were reduced from a large two-story, four 

bedroom concrete structure to a single story 

brick bungalow due to budgetary constraints. 

Over time, the plan of the bungalow has changed 

and the systems, windows and doors have been 

replaced. The Keeper’s Residence standing 

today has been through several renovations but 

maintains a majority of its historic residential 

character. 
Chronology of Development and Use 

National Park Service 43 

Dry Tortugas Keeper’s Residence Timeline 

1916 Early correspondence regarding the need for a new Keeper’s Residence. 

1917 Preliminary plans for new Keeper’s Residence prepared.

1919 Charles H. Johnson appointed Principal Keeper

1920 $6,500 authorized for a two-family residence

1922 June – Materials and construction crew arrive to complete new residence. 

1923 New Keeper’s Residence 90% completed – interior trim work remains to be 

completed. 

1939 U.S. Bureau of Lighthouses amalgamated into the operations of the U.S. Coast 

Guard. 

1951 Keeper’s Residence renovated under scope of “Improvements to Sanitary 

Facilities Project” - scope included removing a portion of the wall between the 

kitchen and original bedroom (now dining room) at the northeast end (rear) of 

residence to create a combination kitchen/dining room; enclosing door opening 

between bathroom and rear bedroom (now dining room) to create a square hall; 

addition of water line; removal and replacement of ceilings with masonite; new 

ceiling light fixtures; greaseproof asphalt tile installed in kitchen, dining room, 

pantry, and hall; windows and doors repaired or replaced as necessary; gutters, 

downspouts, soffits, and roof shingles repaired as necessary; new sink installed 

in kitchen; hot water heater flue installed through the roof; new tile floor and 

wainscot installed in bathroom; new plumbing fixtures added; and a lead pan 

installed under the shower. 

1969 Five window air conditioning units, ceiling exhaust fan, and 2” glass fiber 

insulation in the attic installed in the residence.

1969-

1989 

Lay-in suspended acoustical tile ceiling installed on the interior and awning 

windows installed to replace original double-hung wood windows. 

1971 Fire detection system installed in the residence, with surface-mounted 

ionization detectors placed in the front rooms and self-restoring 135 degree 

combination constant temperature and rate of rise thermal detectors installed in 

the kitchen, dining room, pantry, and hallway. 

1982 The original interior floor plan was altered by adding interior walls to separate 

front room into two separate spaces with a corridor between them. 

1985-

1989 

Rehabilitation of Crew’s Quarters

 New PVC gutters installed at eave 

 Original eave fascia and soffit components removed to repair rafters 

and joist tails – replaced with new 1⁄2” x 14” plywood soffit, 4” 

continuous fiber glass screen, quarter round wood molding, and 1” x 

8” wood fascia. 

 Existing 1” x 12” cornice fascia retained and 7/8” x 33⁄4” molding 
44 Dry Tortugas Lighthouse HSR 

removed. 

 Exterior side door at rear of residence replaced. 

 Floor plan altered by removing the walls installed ca. 1982 and new 

stud partition wall constructed to create a central hallway and second 

bedroom. 

 Vinyl asbestos tile (VAT) and carpeting installed as flooring finish in all 

rooms. 

 Half-inch gypsum wall board and 1” x 2” furring strips installed over 

the plaster walls. 

 Removal of existing lay-in suspended ceiling revealing historic crown 

molding concealed within and installation of gypsum board over the 

original pine ceilings. 

 Original 7/8” x 71⁄2” base board removed and new 3⁄4” x 4” wood 

baseboard and shoe molding installed throughout the residence. 

 Residence rewired – main service to panel retained; all existing wiring 

removed and replaced with non-metallic conduit (NMC); existing 

fixtures and outlets removed and replaced with fluorescent light 

fixtures in the house and incandescent fixtures on the porches; 

electrical panel and fire alarm replaced. 

Post 1989 Installation of existing gray composition asphalt shingle roofing.

March/April 

2002 

HVAC, insulation and high efficiency appliances installed; hallway ceiling lowered to 

improve HVAC; and residence connected to solar power unit. 

May 

2002 

Underground passive solar water heater installed.

December 

2004 

Windows replaced with six-over-six, double-hung Pella architectural series thermo-pane 

windows. 

2009 Development of HSR 
National Park Service 45 

Figure 43: 2009 View of Keeper’s Residence and 

surrounding landscape. 

Physical Description 

Dry Tortugas Keeper’s Residence 

The Keeper’s Residence was constructed in 

1922-23 during a period when the Dry Tortugas 

Light Station was being modernized. It was built 

as living quarters for the principal lighthouse 

keeper and his family. Prior to this, the principal 

keeper as well as two assistant keepers and their 

families were living in the original 1858 keeper’s 

dwelling. The original kitchen building was also 

converted into living quarters during the 1920s 

modernization of the Light Station.

 

Several years of correspondence regarding the 

need for and design of a new keeper’s residence 

ensued following initial requests for a new 

residence in 1916 by the principal keeper. 

Though it is unknown if there was a standard 

design for keeper’s residences in the early 

twentieth century, most residences were 

constructed in an architectural style similar to 

that of other modest homes in the surrounding 

areas.

 1

This was true of the new Keeper’s Residence, as 

it was a bungalow house type designed with 

elements of the Craftsman style that was popular 

in America’s developing suburban residential 

areas during the first part of the twentieth 

century. The one-story brick bungalow was 

designed in a rectangular plan and measured 32’ 

x 51’ (overall outside dimensions). The building 

has load bearing brick masonry walls and woodframe floor and roof structural systems. The 

building’s hipped roof is covered with 

composition asphalt shingles. The exterior wall 

finish is buff yellow brick laid in a modified 

Flemish stretcher bond with contrasting red 

bricks at the building corners. 

An engaged L-shaped front porch wraps 

approximately half-way around the northeast 

 

1

 Ray Jones, The Lighthouse Encyclopedia: The Definitive 

Reference. Guilford, Connecticut: The Globe Pequot Press, 2004, 

95. 

side of the residence. The porch roof structure is 

supported by tapered wood columns resting on 

brick piers trimmed at the corners with coral 

stone buttresses. The brick piers are a mixture of 

yellow and red brick. An engaged rear porch 

provides access to the rear entry into the 

residence. Foundation piers, porch foundations, 

and brick balustrade for the porch steps are 

faced with the same yellow brick as used on the 

rest of the residence. In addition, these masonry 

elements have contrasting red brick arranged to 

create a diamond-shaped pattern. 

Generally, significant changes to the building 

since its construction include replacement of the 

original double-hung wood windows, first with 

metal jalousie windows and then with modern 

double-hung thermo pane window units. The 

louvered wood shutters originally installed on 

the building have been removed. Original 

exterior doors have been replaced with wood 

panel doors and the front door surround has 

been removed and replaced with plywood. 

The original porch balustrade has been removed 

and replaced with turned balusters that are not 

in keeping with the architectural character of the 

building. The original interior floor plan was 

altered and the ceiling and wall surfaces covered 
46 Dry Tortugas Keeper’s Residence HSR 

Figure 44: 2009 view of Keeper’s Residence with concrete 

walkway in foreground. 

with modern gypsum board. A more detailed 

description of existing building characteristics 

follows below. 

Character Defining Features 

Character-defining features of the Keeper’s 

Residence are those elements of the building 

that significantly contribute to the building’s 

character and therefore should be maintained 

and preserved. 

Despite the changes to the residence described 

above, the building retains the overall historic 

architectural character. These characterdefining features include: 

 Isolated and sparsely vegetated subtropical 

setting – The character of the surrounding 

landscape is one of the Light Station and 

Keeper’s Residence most unique and 

important features contributing greatly to the 

resources sense of place. 

 Relationship between the residence and 

tower as well as other associated structures of 

the Light Station 

 Southeast to northwest siting of the building 

with the primary façade facing Fort Jefferson 

 Craftsman Style form and detailing 

 Rectangular plan and one-story height 

 Wood roof and floor framing systems and 

load-bearing brick masonry wall structure 

 Hipped roof with overhanging wood eave 

and slight flair at the soffit 

 White paint color of exterior wood trim and 

other elements -- results from paint sampling 

from the exterior woodwork show eleven 

layers of white and cream paint. 

 Exterior masonry wall finish of buff yellow 

brick with detailing of contrasting red bricks 

alternating courses at building corners and 

diamond-shaped patterning 

 Portland Cement Mortar – results from 

mortar sampling from exterior masonry show 

mortar consisting of one part Portland 

cement and 2.4 parts local carbonate sand 

(contains no lime or natural cement) 

 The original configuration of exterior door 

and window openings on all sides of the 

building 

 Concrete stairs and brick/coral stone cheek 

walls leading to front porch/entrance 

 Unique coral stone buttressing at building 

corners 

 Windows are considered character-defining 

features of the residence -- the existing 

modern units that were installed in 2003 

replicate the appearance and pane 

configuration of the original windows 

 Exterior window trim with flat casings and 

concrete sills 

 Engaged front (east) wrap-around porch with 

tapered wood columns on brick piers with 

coral stone caps and detailing, narrow-board 

ceiling, tongue and groove flooring, and 

cement stairs with brick and cement cheek 

walls 
Physical Description 

National Park Service 47 

Figure 45: Circa 1923 view of Keeper’s Residence nearing completion. 

 Unique coral stone buttresses at building 

corners on the main elevation 

 Engaged rear (south) porch with square 

wood post supports, narrow-board ceiling, 

 tongue and groove flooring, and concrete 

stairs 

 Interior plaster on wood lathe wall finish – 

results from plaster sampling from interior 

plaster show two-coat system with a gypsum 

and sand-based scratch coat and gypsumbased finish coat gauged with lime 

 Interior wood ceiling covered with nonhistoric gypsum board ceiling finish 

 Wood crown molding located at the juncture 

of the original plaster walls and ceilings 

 Interior wood flooring covered with nonhistoric vinyl composition tile and carpeting 

 Interior door and window trim with flat 

casings at the heads and jambs 

Site 

The Dry Tortugas Keeper’s Residence was 

constructed in 1922-23 during a period of 

modernization of the Light Station. The 

Keeper’s Residence is located approximately 150 

feet northeast of the Lighthouse. It is sited 

southeast to northwest with its primary façade 

facing southeast toward Fort Jefferson. 

The surrounding landscape is comprised of 

sand, scrub grass and several palm trees. Existing 

site features include a series of intersecting 

concrete walkways that connect the Keeper’s 

Residence to the light house and other buildings 

at the station. These walkways also connect the 

front of the residence to the rear along the 
48 Dry Tortugas Keeper’s Residence HSR 

Figure 46. Lowest two courses of reddish-brown 

brick of exterior walls above grade. 

Figure 47: One of three interior brick piers 

supporting the Keeper’s Residence. 

Figure 48: Cross-shaped vent in the foundation 

walls providing ventilation. 

Figure 49: Typical past repointing efforts at the 

exterior face of foundation walls. 

Figure 50: Loss of mortar in horizontal and vertical 

masonry joints at southwest front porch wall. 

Figure 51: Loss of mortar in masonry joints and 

evidence of past repointing efforts at left side of 

front porch foundation wall on southeast 

elevation. 

 
Physical Description 

National Park Service 49 

Figure 52: Loss of mortar in masonry joints and 

evidence of past repointing efforts at right side of 

front porch foundation wall on southeast 

elevation. 

Figure 53: Floor framing including 11’ – 11” wood 

girders spanning width of residence. 

Figure 54: Wood girders bearing in a pocket in the 

top three courses of exterior wall on wood ledger 

board. 

southwest elevation. A concrete cistern is 

located adjacent to the residence, approximately 

25’ from the south corner of the house. 

Based on historic photographs produced at the 

time of construction, fencing was constructed 

around the southwest, northwest, and northeast 

sides of the residence. This fence appears to 

have been approximately 2-3’ in height and 

comprised of individual concrete piers with a 

single wood or metal railing extending between 

piers. This fence is no longer extant. It is not 

know when it was removed from the site. 

Structural Systems

Foundation: The level of grade around the 

perimeter of the Keeper’s Residence did not 

permit access to the building’s foundation. The 

exterior load-bearing masonry walls extend 

below grade without interruption. Information 

on the original 1921 architectural plans shows 

load-bearing brick masonry walls extending 

below grade to concrete footings. The interior 

face of the foundation walls are a reddish-brown 

common brick, as are the lowest exposed two 

courses of the exterior walls. (Figure 46) The 

remainder of the exterior foundation walls is 

constructed of the buff yellow brick used on the 

remainder of the residence. 

The first floor is raised above grade 

approximately 28” on wood joists with a 2’-4” 

crawl space below. The floor structure is 

supported by the exterior walls and by three 

interior brick piers. The interior piers are 201⁄2” 

square and extend 27-28” above grade to the 

underside of the floor framing. These piers are 

formed with the same reddish-brown common 

brick used on the interior face of the foundation 

walls (Figure 47). 

Cross-shaped vents in the exterior load bearing 

masonry walls provide air circulation to the 

crawlspace. (Figure 48) There are two vents in 

both the northwest and southeast foundation 

walls, though one vent on the northwest wall has 

been infilled with concrete to accommodate an 

exterior spigot. There are five vents on each of 

the northeast and southwest walls, though one 

on the southwest wall has been infilled with 

concrete. 
50 Dry Tortugas Keeper’s Residence HSR 

Figure 55: Overlap of wood joists on top of girders.

Figure 56: Hatch in ceiling of side porch providing 

access to attic. 

Figure 57: Roof framing at hip ridges. 

Existing Condition: The foundation walls of the 

main house appear sound with no signs of past 

or active settlement or movement of the 

foundation walls. Localized mortar loss and 

evidence of repointed masonry joints indicate 

previous mortar loss due to weathering at all 

foundation walls. (Figure 49) 

Several condition issues were identified with the 

porch foundation walls. These include erosion 

of mortar in masonry joints; past repointing with 

mortar that does not match the historic mortar 

in color and texture; and spalling of face brick. 

Specific areas of damage are identified below. 

 Southwest wall of front porch exhibits loss 

of mortar in horizontal and vertical masonry 

joints. (Figure 50) 

 Left side of the porch foundation wall on 

the southeast elevation (when facing the 

residence) (Figure 51) 

 Right side of the porch foundation wall 

on the southeast elevation (when facing the 

residence) (Figure 52) 

 Porch foundation wall on the southwest 

elevation (when facing the residence) 

Floor Framing: The first floor structure of the 

Keeper’s Residence is raised above grade on a 

wood frame structure. Three girders of paired 3” 

x 12” wood members span the width (northeast 

to southwest) of the residence. The girders are 

11’-11” long and are supported by brick 

buttresses at the exterior walls and set in mortar 

atop the brick piers. (Figure 53) 

Girders support 2” x10” wood floor joists 

spaced at 16” on center. Joists are notched and 

bear in a pocket in the top three courses of the 

exterior wall and rest on a 1” x 5” wood ledger 

board attached to the face of the girders. Four 

brick courses below the plate are corbelled out 

from the wall face to support the load. (Figure 

54) 

The walls are 8” thick with each successive 

corbelled course extending out 1” to provide 

wall widths of 9, 10, 11 and 12” respectively. 

 
Physical Description 

National Park Service 51 

Figure 58: Ceiling joists and decking from the attic. 

Figure 59: V-shaped struts and collar ties of roof 

trusses. 

Figure 60: Vertical struts of roof truss extending 

from mid-span of the rafters to joists. 

Figure 61: Batt insulation in the attic. 

Joists are approximately 139.5” in length and are 

sistered with a 22” overlap at the girders. (Figure 

55) 

The joists are braced by wood cross bridging. 

The bridging is 1” x 3” wood members 16-16.5” 

in length nailed to the joists. The first floor 

decking, as observed from the crawlspace, is 1” x 

5” tongue and groove wood that runs diagonally 

(north to south) to the joists.

Existing Condition: Though the floor framing 

was observed to be generally in sound condition, 

some signs of deterioration and damage were 

noted from the crawlspace. Typical 

deterioration of the framing members from 

moisture and termite activity is evident in Figure 

51 above. The fasteners used in securing the 

flooring framing showed some signs of 

corrosion, however no evidence of loosening or 

shifting of the members was observed. The 

finished floor prevented the visual inspection of 

the floor framing and decking from the interior 

of the residence. 

Roof Framing: Access to the attic of the 

Keeper’s Residence is provided through two 

hatches, one located in the ceiling of the interior 

vestibule and the second located in the ceiling of 

the rear porch. (Figure 56) 

The hipped roof of the Keeper’s Residence is 

framed with 2” x 8” circular-sawn rafters spaced 
52 Dry Tortugas Keeper’s Residence HSR 

FIgure 62. Attic vent open though the roof. 

Figure 63: 2009 view of façade (east elevation). 

Figure 64: 2009 view of south elevation. 

at 16” on center with a 2” x 12” main ridge board 

and 2” x 10” hip ridges. The fasteners of the roof 

framing system in some locations showed minor 

signs of corrosion but generally appeared in 

good condition. No signs of failed fasteners was 

observed and all joinery appeared tight (Figure 

57). 

The ceiling joists are 2” X 10” circular-sawn 

boards at 16” on center spanning the width of 

the structure. The joists are fastened to the 

rafters at the inside face of the eave fascia and 

bear on the exterior brick wall. The patina of the 

rafters and joists are dark brown unfinished 

wood. (Figure 58) 

The roof structure also includes a series of trusses 

that are a variation of the Howe Truss. These 

trusses consist of 2” x 8” V-shaped struts 

extending from the ceiling joists to the rafters on 

either side of the ridgpole and are braced laterally 

with 2” x 6” collar ties spaced 16” on center. 

(Figure 59) 

Two rows of vertical 2” x 8” struts extend from 

the ceiling joists to the rafters at mid-span, with 

one row of struts on each side of the V-shaped 

struts. The roof framing members are attached 

with round-headed common nails that are 

exhibiting some corrosion but generally appear in 

good condition. This roof framing was designed 

to resist wind loads. (Figure 60) 

The roof sheathing, as observed from the attic 

space, consists of 1” x 3” tongue and groove 

wood. The eave of the hipped roof has a slight 

flair at the soffit. Batt insulation has been installed 

in the attic for energy efficiency. Insulation is 

present between the attic floor joists with 

additional insulation laid in several layers over 

the base layer. (Figure 61) 

Existing Condition: The attic space was dry at the 

time of inspection and no evidence of active or 

past leaks was observed. A circular opening, 

most likely for an attic vent, is open through the 

roof framing and roofing and does not have a 

cover or screening. This opening could allow 

moisture to infiltrate the roof and attic of the 

residence (Figure 62). The fasteners used to 

secure structural roofing members appear to be 

in relatively good condition. Some fasteners are 

exhibiting signs of surface corrosion while 

others have not corrosion at all. All of the 

structural roofing members appeared well 

secured. 
Physical Description 

National Park Service 53 

Figure 65: 2009 view of west elevation. 

Figure 66: 2009 view of north elevation, with Light 

Tower in background. 

Figure 67: Torn and missing asphalt roofing 

shingles. 

Exterior Features 

East Elevation: The southeast elevation of the 

Keeper’s Residence is the front elevation and 

faces towards Fort Jefferson. The residence has 

an engaged porch that extends the full width of 

the east elevation and wraps around the 

northwest corner and extends approximately 25 

feet along the north elevation. The porch roof is 

supported by tapered wood columns set on 

brick piers. The piers are trimmed with 

decorative coral stone buttresses. These 

buttresses are unique features of the residence 

that seem to be an attempt by the designers to 

acknowledge the tropical setting of the 

structure. The main wall of the house at the 

southeast elevation is load-bearing brick 

masonry consisting of unpainted buff yellow 

face brick laid in a Flemish stretcher bond with 

contrasting red bricks alternating courses at the 

building corners. The main entrance to the 

Keeper’s Residence is located on this elevation, 

as is the original side entrance into Room 

KR104, currently used as quarters for Coast 

Guard personnel when on the island. This 

elevation also contains one window opening 

located southwest of the main entrance when 

facing the house. This window is a single sixover-six double-hung window. (Figure 63)

South Elevation: The south elevation faces 

toward the Lighthouse. The engaged porch with 

wood post supports, narrow-board ceiling, and 

tongue and groove flooring and the side 

entrance to the residence are located on this 

elevation. This elevation contains four windows 

openings. Two openings have single six-over-six 

double hung windows; the third opening has 

three (3) six-over-six double hung windows; and 

the fourth opening has two (2) six-over-six 

double hung windows. There are five crossshaped foundation vents located on this 

elevation, two venting the side porch, two 

venting the crawlspace of the residence, and one 

venting the area under the front porch. An 

HVAC compressor is located on this elevation at 

the side porch. (Figure 64) 

West Elevation: The west elevation is the rear of 

the residence and faces the Gulf of Mexico. The 
54 Dry Tortugas Keeper’s Residence HSR 

Figure 68: View of single PVC downspout at north 

elevation 

Figure 69: Weather paint finish, rusted nail heads, 

and torn/missing quarter-round and screening at 

the eave soffit. 

Figure 70: Separation of frieze board at east 

corner of building.

side porch is accessed at this elevation via 

concrete steps. This elevation contains four 

windows openings. Two of the openings have 

single six-over-six double hung windows; the 

third opening has two (2) six-over-six double 

hung windows; and the fourth opening has a 

casement window with eight panes in each 

casement. The northern (far left) and southern 

(far right) windows as you face the building were 

covered with metal hurricane shutters during 

the time of the inspection. This elevation also 

contains the access to the crawlspace under the 

residence, which is located behind two propane 

gas tanks that are chained to the building. 

(Figure 65) 

North Elevation: The north elevation faces 

toward the site of the former Carnegie Marine 

Institute. The short leg of the front wrap-around 

porch is located on this elevation. This elevation 

contains six window openings. Four of the 

openings have single six-over-six double hung 

windows; the fifth opening has a smaller sixover-six double hung window; and the sixth 

opening has a two (2) six-over-six double hung 

windows and is located in the inset of the side 

porch. The two eastern-most windows were 

covered with plywood on the exterior during the 

time of the inspection. There are four crossshaped foundation vents located on this 

elevation, two venting the space under the front 

porch and two venting the crawlspace 

underneath the main portion of the residence. 

An HVAC compressor is located on this 

elevation. (Figure 66) 

Roofing: The roof is clad with gray composition 

asphalt shingles. While the exact date of the 

installation of the existing roofing and sheathing 

is not known, it appears to have been installed 

post-1989. 2

Existing Condition: The existing asphalt shingle 

roofing is in sound condition and is functioning 

satisfactorily as there was no indication of 

moisture infiltration or damage. However, there 

are several roof shingles torn and missing that 

need to be repaired and/or replaced. (Figure 67) 

 

2

 Architectural Drawing, “Crew’s Quarters Floor Plan, Dry 

Tortugas Light Station Rehabilitation, Dry Tortugas Light Station, 

Loggerhead Key, Florida,” August 22, 1989, Archives, United 

States Coast Guard 7th District, Miami, FL. 
Physical Description 

National Park Service 55 

Figure 71: View of tar coating the interior face of 

the exterior brick viewed through hole in the 

bathroom wall.

Figure 72: Replacement brick and mortar not 

matching historic materials located to the right of 

the main door on the east elevation 

Figure 73: Erosion of mortar and brick spalling at 

north elevation.

Gutters and Downspouts: The original 

construction drawings indicate that the building 

was intended to have gutters and downspouts. 

Historic photographs dating from the period of 

construction also indicate that the house 

originally had fascia-hung gutters and 

downspouts. Architectural drawings from 1989 

indicate that new PVC gutters were installed at 

that time. The Keeper’s Residence currently has 

no gutters, and a single PVC downspout remains 

on the northeast elevation. (Figure 68) 

Roof Eave and Cornice: The 1920 construction 

specifications state that all exterior trim shall be 

prime grade yellow pine. The roof rafters were 

constructed to terminate at the load bearing 

masonry wall. The lookouts are sistered to the 

rafter ends and extend beyond the end walls to 

form the slight flare in the eave. 

The original 1921 architectural drawings for the 

residence indicate that the boxed eave was 

comprised of a 1” x 18” soffit and 1” x 8” wood 

fascia. This drawing also shows the cornice 

consisting of a 1” x 12” wood fascia with a 7/8” x 

33⁄4” molding. The architectural drawings for the 

residence entitled Barracks Building Air 

Conditioning dated April 10, 1969 confirm the 

existence of the original eave and cornice details 

at that time. 

Architectural drawings entitled Crew’s Quarters 

Floor Plan dated August 22, 1989 indicate that 

the eave fascia and soffit were to be removed 

completely to repair rafters and joist tails. The 

removed materials were replaced with new 1⁄2” x 

14” plywood soffit, 4” continuous fiberglassscreened venting, quarter round wood molding, 

and 1” x 8” wood fascia. The cornice molding 

appears not to have been replaced. Visual 

inspection confirms the characteristics and 

dimensions of the replacement materials 

described above. The eave fascia is overlapped at 

the top by metal drip edge. A wood frieze board 

covers the top courses of the brick wall. 

Existing Condition: The eave and cornice are 

generally sound and attached. No rot or other 

deterioration was observed. The painted finish 

on existing wood features is weathered and 
56 Dry Tortugas Keeper’s Residence HSR 

Figure 74. Spalling brick at west elevation.

Figure 75: Spalling brick at west elevation. 

Figure 76. Vent opening infilled for hose bib at 

west elevation.

deteriorating. The metal flashing and nails are 

rusted. The quarter-round wood molding and 

screening at the eave soffit is torn and missing in 

select locations. (Figure 69) 

The sheet metal flashing is pulling away from the 

eave at the southeast (front) elevation and east 

corner of the residence. The cornice at the east 

corner of the building is separating with an 

approximate 1⁄2” gap at the mitered corner. 

(Figure 70) 

Exterior Walls: The exterior walls of the 

Keeper’s Residence are load-bearing brick. The 

solid walls are two wythes thick. The interior 

wythe, visible from the crawlspace, is reddishbrown smooth-face common brick. The exterior 

wythe of the masonry walls is unpainted lightcolored buff brick with a coarse texture. The 

dimensions of the high-fired exterior brick are 

31⁄4” wide x 21⁄4 high x 71⁄2“ long, and the coursing 

is a Flemish stretcher bond with contrasting red 

bricks at building corners. The interior face of 

the brick walls is coated with tar and the interior 

walls are finished with plaster board and a finish 

coat of plaster. The tar applied to the brick wall 

was observed through a hole in the plaster wall 

of the bathroom. (Figure 71) 

Test results of a mortar sample from the exterior 

wall of the Keeper’s Residence revealed that it 

consists of one part Portland cement and 2.4 

parts local carbonate sand. The analysis 

indicated that the Keeper’s Residence mortar 

did not contain any lime or natural cement. The 

Keeper’s Residence is the only structure at the 

Light Station that does not contain natural 

cement in its mortar. The use of Portland 

cement exclusively in the mortar mix is in 

keeping with a building constructed during the 

early 1920s. 

Archival research supports the use of Portland 

cement and local sand in the construction of the 

Keeper’s Residence. The 1920 specifications call 

for mortar to be composed of “I part [Portland] 

cement and 2-1/2 parts sand. Hydrated lime not 

to exceed 10% by volume of the cement shall be 

used for tempering.” 3

 Although the mortar 

specifications were written for concrete block 

and not brick, the information can certainly be 

applied to the brick. In fact, the ingredients and 

proportions documented in the current lab 

analysis are almost identical to those included in 

the specifications. 

 

3

 “Specifications for a Single Dwelling for Keeper at Dry Tortugas 

Lightstation, Florida,” August 10, 1920. Record Group 26: 

National Archives, Washington, DC, 3. 
Physical Description 

National Park Service 57 

Figure 77: Mortar joint cracking due to oxide 

jacking. 

Figure 78: Mortar joint cracking due to oxide 

jacking. 

Figure 79: Mortar joint cracking due to oxide 

jacking between windows 3 and 4. 

 

Existing Condition: The exterior walls have 

experienced moderate erosion of mortar and 

face brick due to weathering caused by the 

extreme weather conditions of heat, wind, 

water, and sand. Evidence of past repointing 

with mortar not matching the historic mortar 

indicates that these conditions have existed for 

some period of time. For example, portions of 

brick located to the right of the main door on the 

east elevation and at the northwest elevation 

have been replaced with brick and mortar that 

does not match historic brick and mortar. The 

new brick is 9” long with a smoother texture 

than the original 8” brick with a rougher texture. 

The mortar joints are wider than the historic 

joints; the mortar is dark grey in color rather 

than the lighter gray of the historic mortar; and 

the new mortar has a smooth consistency rather 

than the more textured consistency of the 

historic mortar, indicating that the later mortar 

does not contain the local carbonate sand as the 

historic mortar. (Figure 72) 

The areas of damaged masonry are identified 

below. 

 Loss of mortar and spalling brick at lower 

portion of wall on north elevation (Figure 

73) 

 Spalling brick and inappropriate repointing 

on west elevation (Figure 74) 

 Spalling brick at west elevation (Figure 75) 

 Infill of crawlspace vent for hose bib on west 

elevation (Figure 76) 

 Cracking in mortar joint on northwest 

elevation 

 Spalling brick to right of Window 15 at 

south corner on southwest elevation 

 Loss of mortar at lower wall section below 

Window 15 on south elevation 

The wall areas above and between the windows 

have experienced masonry joint cracking 

extending from the top corners of the windows 

horizontally across the face brick of the exterior 
58 Dry Tortugas Keeper’s Residence HSR 

Figure 80: Mortar joint cracking due to oxide 

jacking between windows 4 and 5. 

Figure 81: View of boxed eave and cornice at east 

corner of residence. 

Figure 82: Dorothy Krotzer of Building 

Conservation Associates, Inc. (BCA) works to obtain 

a paint sample from the Porch trim of the Keeper’s 

Residence. 

walls. These conditions are caused by jacking 

from oxidation and associated expansion of the 

steel lintels embedded in the masonry walls. This 

damage is occurring in multiple locations that 

are identified by elevation below. 

South Elevation 

 Above and between Windows 14 and 15 

(Figure 77) 

West Elevation 

 Above and between Windows 8, 9 and 10 

(Figure 78) 

North Elevation 

 Above and between Windows 3 and 4 

(Figure 79) 

 Above and between Windows 4 and 5 

(Figure 80) 

Front Porch Roof, Eave, Cornice, and 

Supports: 

The L-shaped front porch extends 

approximately 25’ along the north elevation of 

the residence and is engaged within the main 

roof. 

The boxed eave has a slight overhang and is 

formed by the 12” soffit comprised of a 1”x 8” 

plywood with the outer 4” section screened to 

provide ventilation to the attic space. The top 

portion of the 1” x 4” eave fascia is overlapped 

by metal drip edge. The header for the porch 

roof is formed by a 1” x 4” fascia board and 1” x 

6” soffit with quarter-round wood molding. 

(Figure 81) 

The porch roof is supported by five tapered, 

boxed, wood columns with wood plinths. The 

columns are supported by yellow and red brick 

piers with concrete caps and are trimmed in 

coral stone along their outside vertical edges. 

The columns taper from 101⁄2” at the bottom to 

7&1⁄2”at the top. 

Results from paint sampling from the exterior 

woodwork of the Keeper’s Residence indicate 

that the building was originally painted white. 
Physical Description 

National Park Service 59 

Figure 83: Crack in the concrete plinth on the far 

left porch pier on the southeast elevation. 

Figure 84: Crack in east side of plinth on the far 

left porch pier at east elevation.

Figure 85: No. 3: Crack in the east side of plinth on 

the far right porch pier at east elevation.

Samples removed from the front porch trim 

show 11 layers of white and cream paint. (Figure 

82) 

In addition, historic photographs of the 

residence show white-colored trim and the 

preliminary specifications dating to 1917 state 

that all woodwork was to be painted white. 

Existing Condition: There is masonry damage in 

multiple locations at the front porch piers. There 

are multiple cracks in the mortar joints, bricks, 

and concrete caps of the porch piers. This 

damage is almost certainly related to the 

corrosion and expansion of tie rods and anchor 

plates embedded in the piers to secure the porch 

roof. There is also evidence of past cracks that 

have been filled with epoxy filler. The specific 

areas of masonry damage to the porch piers are 

identified below. 

No 1: Crack in the southwest side of the plinth 

on the far left porch pier on the southeast 

elevation (facing residence) (Figure 83) 

No. 2: Crack in the east side of the plinth on the 

far left porch pier on the east elevation (facing 

residence) (Figure 84) 

No. 3: Crack in the east side of the plinth on the 

far right porch pier on the south elevation and 

vertical crack between the brick and coral stone 

buttress (facing residence) (Figure 85). The 

buttresses are experiencing some weathering but 

are in good condition. 

No. 4: Crack in the north side of the plinth on 

the far left porch pier on the north elevation and 

cracks between the brick and coral stone 

buttress (facing residence)

No. 5: Cracks in the brick and mortar joints at 

the top of the far right pier on the north 

elevation (facing residence) (Figure 86)

No. 6: Crack in the west side of plinth and top 

three courses of the second pier from the left on 

the south elevation (facing residence) (Figure 

87) 

No. 7: Past repair of crack in the west side of 

plinth of the second pier from the right on the 

east elevation (facing residence)

No. 8: Crack in brick and masonry joints on the 

west side of the far left pier on the east elevation 

(facing residence) 
60 Dry Tortugas Keeper’s Residence HSR 

Figure 86: Cracks in brick and mortar joints at the 

top of the far right pier on the north elevation.

Figure 87: Crack in the west side of plinth and top 

three courses of the second pier from the left on 

the south elevation.

Figure 88: Weathered paint finish on the far right 

porch column at east elevation. 

No. 9: Crack in the plinth, brick, and masonry 

joints on the south side of the far right pier on 

the north elevation (facing residence)

The paint on wood elements of the porch is at 

the end of its life span as exhibited by flaking 

and weathering of the paint, particularly along 

the eave, cornice, and wood columns. For 

example, paint finish at the far right porch 

column at the east elevation is deteriorated due 

to weathering. (Figure 88) 

Front Porch Ceiling: The porch ceiling is 1” x 

21⁄2” wood painted white with 1⁄2” space between 

boards to provide attic ventilation. There is a 

hole cut in the ceiling for a light fixture but no 

fixture existed at the time of inspection. (Figure 

89) 

Existing Condition: The front porch ceiling has 

multiple layers of paint. The outer layers are 

chipping and flaking. The heads of the nails used 

to secure the ceiling boards are corroded due to 

exposure to salt. (Figure 90) 

Front Porch Railing: The non-historic porch 

balustrade is constructed of wood. The top and 

bottom rails are 2” x 4” boards painted white. 

The stock balusters are 281⁄2” long. (Figure 91). 

The original porch balusters shown in historic 

images of the Keeper’s Residence were closely 

spaced square wood members. At least one other 

generation of balusters was installed on the 

building. Mid-twentieth century images of the 

building show widely spaced rectangular 

balusters with angled balusters at the piers. 

Existing Condition: Generally, the wood is sound 

and nails are secure. The baluster post at the 

south corner of the house on the southwest 

elevation is separating and the face board is 

detached. (Figure 92) 
Physical Description 

National Park Service 61 

Figure 90: Deteriorating paint finish of the front 

porch ceiling. 

Figure 91: View of front porch railing with wood 

top and bottom rails and balusters. 

Figure 92: Damage to baluster post at the south 

corner of the porch. Figure 89: View of front porch ceiling with 1⁄2” gap 

between boards for attic ventilation. 

Front Porch Floor: The porch flooring is 1” x 5” 

tongue and groove wood painted blue-green and 

running east to west. The V-joint and 5”-wide 

boards are atypical features of flooring materials, 

even for the 1920s, suggesting that the existing 

flooring could be a later addition. 

Existing Condition: The porch flooring is 

generally sound structurally. There are multiple 

individual floor boards that are damaged at their 

outside ends. This damage includes broken 

boards, split & cracking ends and rot damage to 

boards. 

Counting from the south corner across the front 

of the porch, the damaged boards are outlined 

below. 

 Boards 8 & 9 -- broken ends 

 Board 12 -- joint separating on left side 

 Board 42 -- broken end (Figure 93) 

 Board 47 -- joint separating 

 Board 62 -- joint separating 

 Board 68 -- split and cracked

 Board 71 -- split and joint separating at right 

side

Counting from the southeast corner along the 

northeast side of the porch, the damaged boards 

include:

 Board 5 – rot damageBoard 8 – rot damage 

(Figure 94) 

 Boards 14, 15 & 17 – rot damage 

The fascia below the porch decking is 1” x 4” 

wood painted blue-green with a simple bead 

ogee profile along its top edge. This trim is 

cracked and loose at various locations across the 

east and north elevations of the front porch. 
62 Dry Tortugas Keeper’s Residence HSR 

Figure 93: Broken tongue and groove flooring of 

front porch. 

 Figure 94. Rot damage to tongue and groove 

flooring of front porch. 

Figure 95: View of concrete steps and brick cheek 

walls at front entrance. Figure 96: Separation of joint between cheek wall 

and pier at top of stairs. 

Areas where this condition occurs are identified 

below. 

 East elevation between south corner of 

building and stairs

 East elevation at top left of stairs at southeast 

elevation

 North elevation between first and second 

porch piers (from left to right) 

 North elevation between second porch pier 

and east corner of house (from left to right)

Front Porch Stairs: The porch is accessed from 

the front by concrete steps consisting of six (6) 

risers and six (6) treads from the concrete 

sidewalk to the porch floor. The treads measure 

111⁄2” and risers measure 7”. The steps are 

painted the same blue-green color as the porch 

floor. Brick cheek walls flank the stairs and splay 

out from the porch to the bottom step. The 

cheek walls are topped with a coral concrete 

cap. (Figure 95)

Existing Condition: The porch stairs are in sound 

condition. The stair cheek walls, however, 

exhibit signs of deterioration including spalling 

brick and separation between joints of the cheek 
Physical Description 

National Park Service 63 

Figure 97: Separation of joint between stairs and 

cheek wall. 

Figure 98: View of side porch – eave screening is 

torn and missing; metal anchors and brackets are 

corroding and staining the exterior paint. 

Figure 99: View of side porch ceiling with 1⁄2” gap 

between boards. 

walls and front porch piers. Individual 

conditions are illustrated below. 

 Spalling of brick due to weathering 

o At the southwest side of the left cheek 

wall 

o At the northeast side of the right cheek 

wall 

o At top left stair pier

 Separation of the joints between the cheek 

wall and porch piers due to settlement of the 

stairs away from the residence

o Between the left cheek wall and porch pier 

at the top of the porch stairs on the 

southwest elevation

o Between cheek wall and pier at top of 

stairs on the north elevation (Figure 96) 

 Separation of joint between the stairs and 

inside face of cheek wall (Figure 97) 

Side Porch: The side porch measures 18’ – 1” 

long and 6’ – 6” wide, and is accessed from the 

west elevation and extends along the south 

elevation. The current porch configuration 

conforms to the 1921 architectural plans. 

Historic photographs dating to the period of 

construction show that the side porch originally 

had wood lattice between the supporting posts. 

The wood lattice has been removed at some 

point in the past and the space between the posts 

is open. 

Side Porch Roof, Eave, Cornice, and Supports:

The side porch is engaged within the main roof 

of the residence and the porch eave is the same 

as that around the house. The eave and drip edge 

are the same as that on the front porch 

(described above). The porch roof is supported 

by two 8” x 8” chamfered posts. Porch posts 

have a 1” x 8” base trim at the bottom, and a 2” x 

111⁄2” wood cap at the top of the posts. 

Existing Condition:The wood elements of the 

roof, eave, cornice and posts are sound. The 

screening of the eave soffit is torn and missing in 

sections. In numerous locations along the side 

porch cornice, metal anchors and brackets are 

attached to the exterior of the cornice. These 

items are corroding and staining the exterior 

paint. (Figure 98) 
64 Dry Tortugas Keeper’s Residence HSR 

Figure 100: Deteriorating paint finish and rusted 

nail heads on side porch ceiling. 

Figure 101: Hairline cracks in masonry joints at the 

northwest porch wall. 

Figure 102: Eroded and cracked mortar joints in 

side porch foundation wall. 

Side Porch Ceiling: The side porch ceiling is 1” 

x 21⁄2” boards with 1⁄2” space between boards to 

provide attic ventilation. A 231⁄2” x 28” access 

hatch to the attic space is located in the ceiling of 

the porch. The hatch opening has a 3” 

beadboard trim on all sides. A porcelain light 

fixture with metal junction box is located in the 

center of the porch ceiling. (Figure 99)

Existing Condition: The side porch ceiling has 

multiple layers of paint which is chipping and 

flaking. Heads of nails used to secure the ceiling 

boards are corroded. (Figure 100) 

Side Porch Walls: The porch walls are the south 

and west walls of the residence. The porch 

foundation walls are the same yellow and 

reddish-brown face brick used on the rest of the 

residence.

Side Porch Walls: The porch walls are the south 

and west walls of the residence. The porch 

foundation walls are the same yellow and 

reddish-brown face brick used on the rest of the 

residence. 

Existing Condition: The west masonry porch wall 

has cracks in the mortar joints extending seven 

courses down from the bottom of the cornice. 

(Figure 101) 

The side porch foundation wall also has cracks 

in the mortar joints. (Figure 102) The wood 

fascia board under the floor at the masonry 

foundation wall is missing. 

Side Porch Floor: The porch flooring is 3⁄4” x 5” 

tongue and groove wood flooring running south 

to north. The floor boards, painted a blue-green 

color, are 78” long with 3% slope from the side 

of the residence and extend 91⁄2” beyond the face 

of the brick foundation wall. This long overhang 
Physical Description 

National Park Service 65 

Figure 103: Damage to outside ends of side porch 

flooring – boards 5, 6, 7, 8 and 10. 

Figure 104: Damage to outside ends of side porch 

flooring – boards 35 and 39. 

Figure 105: View of side porch concrete stairs. 

is presumably due to a non-historic addition to 

the porch that has since been removed.

Existing Condition: The porch floor structure is 

generally in sound condition. However, there 

are multiple individual floor boards that are 

damaged at their outside ends. This damage 

includes broken boards, split & cracking board 

ends, and joint separation between boards. 

From the left side facing the porch, the damaged 

boards include: 

 Boards 5, 6, 7, 8, 10, and 20 (Figure 103) 

 Boards 35 and 39 (Figure 104)

Side Porch Stairs: The porch is accessed by 

concrete stairs consisting of six (6) risers and 

treads from the concrete walkway at grade to the 

porch floor. The treads measure 111⁄2” and risers 

63⁄4”. The steps are painted white. The stair 

railing has upper and lower 2” x 4” wood rails 

nailed to a 4” x 4” wood post. (Figure 105) 

Existing Condition: The stair and porch railings 

are generally sound. The nails are loose and 

there is some separation between the 1” x 4” and 

2” x 4” wood forming the porch rail support 

post at the northwest wall of the porch. (Figure 

106) 

Doors:The Keeper’s Residence has three 

exterior doors.

Front Door (D-1): The front door is located on 

the east or primary elevation. This doorway has 

been altered since the residence was 

constructed, possibly at the same time as the 

floor plan changes were made in the mid-1980s. 

The single wood door shown on the 1921 

architectural plans had two vertical rectangular 

panels below a six-light glazed upper panel. 

Flanking the door on both sides were sidelights 

that included a single vertical wood panel below 

a six-light glazed upper panel. The elevations 

also show a simple head detail of a single soldier 

course of buff yellow brick. 

The door frame is still intact, but the existing 

door is a non-historic single six-panel wood 

door measuring 6’-10” x 3’-0” wide x 13⁄4” thick 

with a metal door knob and butt hinges. The 

sidelight frame is still in place but the sidelight 

sash and panel below have been removed and 
66 Dry Tortugas Keeper’s Residence HSR 

Figure 106: Separation between the wood porch 

rail post at northwest wall. 

Figure 107: Non-historic door and sidelights infilled 

with plywood at the front entrance (D-1). 

replaced with plywood painted white. (Figure 

107) A steel lintel supports the brick above the 

door frame and the brick header is intact. 

The existing front door jamb and sidelight frame 

are comprised of wood members, as detailed in 

the profile sketch below. (Figure 108) 

The threshold at the front door is thought to be 

original. It is a 31⁄2” piece of wood on top of a 6’-

3” long continuous sill of concrete that extends 

the width of the rough opening. The concrete sill 

has as 10% slope and the threshold is painted 

blue/green. (Figures 109 & 110) 

Side Door (D-2): A second door is located in the 

east elevation and provides access from the 

porch to Room KR104. This door has been 

altered since the residence was constructed. The 

single wood door shown on the 1921 

architectural plans had two vertical panels above 

and two vertical panels below a single horizontal 

middle panel. The existing door is a non-historic 

single four-panel wood door measuring 6’-10” x 

2’-10” wide x 13⁄4” thick with a metal door knob. 

The door frame is wood with a steel lintel 

carrying the masonry above the door opening. 

(Figure 111)

Rear Door (D-6): The rear door is located on 

the south elevation. This door has been altered 

since the residence was constructed. The single 

wood door shown on the 1921 architectural 

plans had two vertical panels above and two 

vertical panels below a single horizontal middle 

panel. The existing door is a single six-panel 

wood door measuring 6’-10” x 3’-0” wide x 13⁄4” 

thick with a metal door knob and steel butt 

hinges. (Figures 112 & 113) 

The wood threshold at the back door is 31⁄4” 

wide over a 3’-4” long x 4” high block of coral 

concrete. The coral concrete has a 5% slope. 

The threshold is painted blue/green. Profiles of 

the back door jamb and threshold are illustrated 

in the details attached to the finish schedule. 

(Figure 114) 

Figure 108: Profile of the existing door jamb and 

sidelights at the primary entryway (D-1). 
Physical Description 

National Park Service 67 

Figure 109: Threshold at primary entryway (D-1) 

with wood atop a continuous stone sill. 

Figure 110: Profile of the existing threshold at the 

front entrance (D-1). 

Figure 111: Non-historic door at side entrance on 

east elevation (D-2). 

Existing Condition: The doors and frames are 

generally in good condition. The wood is solid 

and the joints are sound. The finish on the 

exterior face of all doors is slightly weathered 

due to exposure to the elements. The steel lintels 

above the door frames show minor corrosion. 

(Figure 115) 

The paint finish on the threshold at the 

secondary front door (D-2) is chipped and 

cracked in select locations. Heads of nails used 

to fasten weather stripping to the secondary 

front door are rusted. (Figure 116) 

Windows: There are fifteen windows in the 

Keeper’s Residence. One window is located at 

the east elevation; four windows at each of 

the south and west elevations; and six 

windows at the north elevation. 

Available records from the National Park Service 

indicate that the windows were replaced in 2004. 

The existing windows are six-over-six, doublehung, Pella, architectural-series, thermo=pane 

windows. 4

 The original louvered wood shutters 

shown in historic images of the building have 

been removed from the residence. Metal 

hurricane shutters and guide tracks are secured 

to the brick masonry and concrete sills with 

metal screws. Several windows were covered 

with the hurricane shutters at the time of 

inspection. 

All windows have a steel lintel spanning the 

openings at the head. Each window also has a 

coral concrete sill measuring 441⁄2” long x 4” high 

with a wood sub sill. The individual panes are 9” 

wide x 16” high with 1” muntins. At the interior 

of the windows, a 1” x 6” wood sill and 1” x 31⁄2” 

wood apron are typical. All windows also have 

1” x 4” flat wood trim at the head and jamb 

casings. The jamb trim is joined to the head trim 

with butt joints. (Figure 117) 

Brief descriptions of each window are provided 

below organized by building elevation. The 

windows are numbered for ease of reference on 

the existing floor plan drawing. 

 

4

 “Replace Windows – Lighthouse Keepers Quarters - Loggerhead 

Key, PMIS 48292,” September 13, 2006 (date of last update), 

National Park Service, Southeast Regional Office, Atlanta, GA. 
68 Dry Tortugas Keeper’s Residence HSR 

Figure 112: Interior face of non-historic door at 

side entryway (D-6). 

Figure 113: Profile of the existing door jamb at the 

back door (D-6). 

Figure 114: Profile of the existing threshold at the 

back door (D-6). 

East Elevation 

 Window 1 (W-1) is located to the left of the 

main entrance (facing the residence) in the 

 living room (KR101). This window is sixover-six double-hung sash measuring 6’-2” 

high x 3’-8”wide. 

North Elevation 

 Window 2 (W-2) is a pair of six-over-six 

double-hung sash inset within the side 

porch in the living room (KR101) that 

measure 5’-5” high x 6’ wide. 

 Window 3 (W-3) and Window 4 (W-4) are 

each six-over-six double-hung sash in the 

Coast Guard Quarters room (KR104) 

measuring 6’-2” high x 3’-2” wide. 

 Window 5 (W-5) is six-over-six double hung 

sash in the bathroom (KR106) that measures 

4’-5” high x 3’ wide. 

 Window 6 (W-6) and Window 7 (W-7) are 

each six-over-six double-hung sash in the 

dining section of the kitchen (KR107) 

measuring 6’-2” high x 3’-2” wide. 

West Elevation 

 Window 8 (W-8) and Window 9 (W-9) are 

each six-over-six double-hung sash in the 

dining section of the kitchen (KR107) 

measuring 4’-5” high x 3’ wide. A drawing of 

interior of Window 8 is illustrated in the 

details attached to the finish 

schedule.Window 10 (W-10) is a pair of 

double-hung sash in the kitchen (KR107) 

measuring 5-5” high x 6’ wide. 

 Window 11 (W-11) is casement with eightlight sash in the bedroom. (KR103) 

Figure 115: Steel lintel above primary door (D-1) exhibits 

minor corrosion. 
Physical Description 

National Park Service 69 

Figure 117: View of interior window with typical 

sill, apron and casings. 

Figure 118: Rusted steel lintel above the opening 

for Window 2. 

Figure 119: Damage to concrete sill of Window 2 

from the metal shutter track. 

South Elevation 

 Window 12 (W-12) is six-over-six doublehung sash in the kitchen (KR107) measuring 

5’-5” high x 3-6” wide. 

 Window 13 (W-13) is six-over-six doublehung sash in the laundry room (KR105) 

measuring 5’-5” high x 2’-6” wide. 

 Window 14 (W-14) is a set of three six-oversix double-hung sash in the bedroom 

(KR103) measuring 5’-5” high x 10’ wide. 

 Window 15 (W-15) is a pair of six-over-six 

double-hung sash in the living room 

(KR101) measuring 5’5” high x 6’ wide. 

Existing Condition: While the window units 

themselves are in sound condition, the steel 

lintels and coral concrete sills are in a 

deteriorating condition. As described above in 

the Exterior Wall section of this report, the steel 

window lintels over the windows are severely 

rusted causing extensive jacking of brick along 

the window heads and extending between 

windows. (Figure 118) 

It is recommended that new wood louvered 

shutters that match the historic condition be 

fabricated and installed on the building (See 

Figure 45). It should be noted that both awning 

(Bahamian Style) and side hinged shutters were 

used on the building depending on the window 

configuration. These variations in shutter type 

should be matched as part of the restoration of 

these features. 

Figure 116: Rusted lintel and nail heads at 

secondary front door (D-2). 
70 Dry Tortugas Keeper’s Residence HSR 

In addition, the aluminum tracks for the 

hurricane shutters installed at the window heads 

and sills have caused cracking and chipping of 

the brick heads and concrete sills and cracking 

along the brick mortar joints. The individual 

instances of masonry damage to window 

elements are outlined below. 

Window 2 – chipping and cracking of the 

concrete sill (Figure 119) 

Window 7 – cracking of bricks and along mortar 

joints below window sill (Figure 120) 

Window 9 – chipping of concrete sill (Figure 121) 

 

Figure 120: Cracks in the masonry and mortar 

joints below Window 7. 

Figure 121: Damage to concrete sill of Window 9. Figure 122. Cracked concreted sill of Window 15. 
Physical Description 

National Park Service 71 

Interior Features 

Schedule of Existing Finishes: The following 

Schedule of Finishes documents the finishes and 

their characteristics identified in the Keeper’s 

Residence. A Summary Description of Interior 

Conditions follows the Schedule of Finishes. 

(below) 
72 Dry Tortugas Keeper’s Residence HSR 

Moldings 

General 

Flooring: The original flooring for all rooms of 

the Keeper’s Residence was yellow pine. As 

described in the 1920 specifications, the “finish 

floor shall be 7/8 x 3-1/4 inch prime grade, edge 

grain, long leaf yellow pine, closely driven up, 

and blind nailed.” The original flooring was 

covered with tile or carpeting in the mid-to-late 

1980s. According to Coast Guard architectural 

plans entitled Crew’s Quarters Floor Plan dated 

August 22, 1989, vinyl asbestos tile (VAT) was 

installed in Rooms KR101, KR102, KR105, 

KR106, and KR107 as part of this project. 

Carpeting was installed in Rooms KR103 and 

KR104. It is likely that the tile and carpeting 

were laid directly over the original pine flooring. 

Visual inspection cannot determine the presence 

or absence of asbestos in the floor tile. Given the 

possibility that the tile could contain asbestos, it 

should be tested and if asbestos is found, 

removed and abated. 

Walls: Gypsum wall board covers the original 

plaster and wood lathe walls throughout the 

residence. According to architectural plans 

Crew’s Quarters Floor Plan dated August 22, 

1989, 1⁄2” drywall was installed on 1” x 2” furring 

strips at 16” on center over the original plaster. 

The gypsum wall board extends from the floor 

to a height approximately 12” below the ceiling, 

revealing the top portion of the historic plaster 

walls and original crown molding. 

Test results from samples of original interior 

plaster revealed that the typical interior plaster 

finish is a two-coat system, with a gypsum and 

sand-based scratch coat and gypsum-based 

finish coat gauged with lime. The finish coat is 

consistent with a Keene’s cement mixture. 

Keene’s cement is a slow-setting, hard-finish 

plaster produced by burning very pure gypsum 

at high temperatures and treating the material 

with alum or other chemicals during the 

manufacturing process. 70 These findings 

indicated that a different plaster was used than 

originally outlined in the 1920 specifications, 

which called for a scratch coat comprised of one 

part cement, two parts sand, and 1/10th part 

hydrated lime and a finish coat composed of a 

cement plaster similar to the U.S. Gypsum 

Company’s “’Adamant,” a fire-resistant type of 

early drywall. 

Ceilings: The ceiling in all rooms of the 

residence is gypsum board, most likely 1⁄2” or 

5/8” thick. The original ceiling material, as 

outlined in the 1920 specifications, was 7/8” x 

 

70 Edwin C. Eckel. Cements, Limes and Plasters: Their Materials, 

Manufacture and Properties. Michigan: Donhead Publishing Co., 

2005 (originally published 1905), 78. 

Figure 123: Interior crown moldings Types C1 – C5. 

Figure 124: Interior crown moldings Types C1 – C5.
Physical Description 

National Park Service 73 

31⁄4” tongue and groove yellow pine. The original 

pine ceiling boards are visible below the 

insulation in the attic. Architectural drawings 

from the 1951 project entitled Improvements to 

Sanitary Facilities indicate that the existing 

ceilings were to be removed and replaced with 

masonite. It appears that this work was not 

completed. 

Architectural drawings entitled Barracks 

Building Air Conditioning, April 10, 1969, 

indicate that the original pine ceilings and wood 

crown molding are intact. The project called for 

installation of 2” glass fiber insulation in the 

attic. 

According to architectural plans entitled Crew’s 

Quarters Floor Plan dated August 22, 1989, the 

existing ceiling at that time was a lay-in 

suspended acoustical tile ceiling. These drawings 

call for retention of the lay-in suspension 

structure and 100% replacement of the 

acoustical tile panels. These drawings also show 

existing 6” blanket insulation within the 

suspended ceiling. The lowered gypsum board 

walls approximately 12” below the original 

plaster wall and ceiling joint indicate that the 

suspended ceiling was installed in the residence 

at some point after the building was constructed 

and likely removed circa 1985 - 1989 and 

replaced with the existing gypsum board applied 

directly over the original pine ceilings. This is 

further supported by the slight overlap of the 

gyp board ceiling over the top of the historic 

crown molding. 

Moldings: 

Most rooms have wood baseboards, moldings at 

the top of the gypsum board walls, and crown 

molding at the juncture of the plaster wall and 

ceiling joint. Specific molding characteristics are 

summarized below by room. 

Living/Berthing Room (KR101) 

Flooring: The existing flooring of Room KR101 

Figure 125: View of Living/Berthing Room facing north. 
74 Dry Tortugas Keeper’s Residence HSR 

is 12” x 12” square vinyl asbestos tile (VAT) in an 

off-white color with brown speckles. The tile 

appears to have been laid directly over the 

tongue-and-groove flooring. The floor tile is a 

potential source of asbestos from the materials 

used to create the tile and likely the mastic used 

to secure the tile in place. 

Walls: The original plaster walls in Room KR101 

are covered with 1⁄2” gypsum wall board. An 

HVAC vent has been cut into the historic plaster 

of the southeast wall approximately 4” below the 

historic crown molding. 

Ceiling: The existing ceiling in Room KR101 is 

gypsum board, most likely 1/2” or 5/8” thick.

Moldings: A typical 41⁄4” wood baseboard with a 

3⁄4” base shoe molding painted white are present 

in Room KR101. A wood molding is located at 

the top of the gypsum board walls below the 

historic plaster wall. The historic crown molding 

is a 4” two-piece ovolo crown mold and picture 

rail. The door opening in the east elevation and 

window openings in this room have a 7/8” x 41⁄4” 

flat wood trim at the head and jamb casings. The 

jamb trim is joined to the head trim with butt 

joints. The moldings in Room KR101 are in 

sound condition and appropriately attached. 

The baseboard (B1) and crown molding (C4) are 

illustrated in Figure 124 above. 

Fixture: There is a single fluorescent light 

fixture located in the center of the ceiling of this 

room. 

Existing Condition: The condition of the finishes 

in Room KR101 is generally good. Items noted: 

 The tile is uneven just inside the front door. 

This is most likely due to poor underlayment 

and/or moisture infiltration from below 

(Figure 128) 

 There is a narrow hairline crack in the 

visible portion of the plaster wall at the east 

corner of this room. The diagonal crack 

begins at the corner and runs northwest 

down the length of the visible portion of the 

plaster wall. (Figure 129)

Central Hallway (KR102) 

Flooring: The existing flooring in Room KR102 

is the same white and brown 12” x 12” vinyl 

asbestos tile (VAT) characteristic found 

throughout the residence. The floor tile is a 

Figure 126: Uneven vinyl tile in living room. 

Figure 127: Hairline crack in the plaster wall at the 

east corner in living room.

Figure 128: Peeling paint at the southeast wall just 

below the ceiling. 
Physical Description 

National Park Service 75 

potential source of asbestos from the materials 

used to create the tile and likely the mastic used 

to secure the tile in place.

Walls: The wall finish in Room KR102 is the 

same 1⁄2” gypsum wall board characteristic found 

throughout the residence. As noted below, the 

ceiling in the central hallway was lowered to 

conceal the HVAC ductwork. The historic 

plaster wall finish and crown molding remain 

intact above the dropped ceiling. 

Sampling and microscopic analysis of the wall 

finish and crown molding in the central hall 

above the dropped ceiling revealed that the walls 

were originally painted a pale gray-green and the 

molding was painted white after having been 

sealed with a clear coat. Testing further revealed 

that the three-coat paint system outlined in the 

1920 specifications was followed, though the 

paint color used was the pale gray-green instead 

of the white called for in the specifications.

Ceiling: The existing ceiling in Room KR102 is 

the same gypsum board (most likely 1/2” or 5/8” 

thick) characteristic found throughout the 

residence. The ceiling in Room KR102 was 

lowered in 2002 to conceal the HVAC air 

handler and ductwork above. The dropped 

ceiling structure is wood frame. The earlier 

ceiling remains intact above the dropped ceiling 

and is visible from the hatch access to the attic. 

The earlier ceiling in this area appears to be a 

fiber board material such as Homasote.

Moldings: A typical 41⁄4” wood baseboard with a 

3⁄4” base shoe molding painted white are present 

in Room KR102. There is no crown molding at 

the wall/ceiling juncture of the dropped ceiling. 

However, the historic crown molding is intact 

above the dropped ceiling and visible from the 

hatch access to the attic. The historic crown 

profile is a 5&1/8” two-piece quarter-round, 

double-ogee crown mold. The moldings in 

Room KR102 are in sound condition and 

appropriately attached. The baseboard (B1) and 

crown molding (C1) are illustrated in Figure 124 

above. 

Figure 129: View of Central Hallway facing west toward Kitchen. 
76 Dry Tortugas Keeper’s Residence HSR 

Fixture: There is a single fluorescent light fixture 

located in the center of the ceiling of this room.

Existing Condition: The condition of the finishes 

in Room KR102 is generally sound. Items noted 

include peeling paint at the southeast wall at its 

juncture with the ceiling. (Figure 130) 

Bedroom (KR103) 

Flooring: The existing flooring in Room KR103 

is low-cut orange carpeting. According to Coast 

Guard architectural plans entitled Crew’s 

Quarters Floor Plan dated July 19, 1985, the 

flooring installed in this room at that time was 

carpet. The carpeting was most likely installed 

over the original pine flooring.

Walls: The wall finish in Room KR103 is the 

same 1⁄2” gypsum wall board characteristic found 

throughout the residence. The gypsum board 

has been applied over the plaster of the three 

original walls in this room and was used to finish 

the northeast wall when it was constructed ca. 

1985. An HVAC vent has been cut into the 

historic plaster of the northeast wall 

approximately 4” below the historic crown 

molding. 

Ceiling: The existing ceiling in Room KR103 is 

the same gypsum board (most likely 1/2” or 5/8” 

thick) characteristic found throughout the 

residence. 

Interior Door: The existing door to this room 

(D-3) is a hollow-core wood door that measures 

82” high x 34” wide x 13⁄4” thick and has a metal 

door knob and butt hinges. 

Moldings: A typical 41⁄4” wood baseboard with a 

3⁄4” base shoe molding painted white are present 

in Room KR103. A wood molding is located at 

the top of the gypsum board walls below the 

historic plaster wall. The historic crown molding 

is 41⁄2” two-piece ovolo, fascia crown mold. The 

door opening in this room has 1” x 21⁄2” wood 

trim at the head and jamb casings with mitered 

corners. The windows have 7/8” x 41⁄4” flat wood 

trim at the head and jamb casings. The jamb trim 

is joined to the head trim with butt joints. The 

moldings in Room KR103 are in sound 

condition and appropriately attached. The 

Figure 130: View of Bedroom facing west. 

Figure 131: View of Bedroom facing southeast. 

Figure 132: Peeling paint on the southwest wall 

along the door frame. 
Physical Description 

National Park Service 77 

Figure 133: Hairline crack in the plaster wall at the 

south corner. 

Figure 134: Torn gypsum wall board at the 

southeast wall. 

baseboard (B2) and crown molding (C3) in 

Room KR103 are illustrated in Figure 124 above. 

Fixture: There is a single fluorescent light 

fixture located in the center of the ceiling of this 

room. 

Existing Condition: The condition of the finishes 

in Room KR103 is generally sound. Items of 

concern regarding condition include peeling 

paint on the southwest wall along the door 

frame. (Figure 134) 

There is a narrow crack in the visible portion of 

the plaster wall above the drywall at the south 

corner of the bedroom. The diagonal crack 

begins just below the historic crown molding 

and runs down the visible portion of the plaster 

wall. (Figure 135) 

Coast Guard Quarters (KR104) 

Flooring: The existing flooring in Room KR104 

is the same low-cut orange carpeting found in 

Room KR103. 

Walls: The wall finish in Room KR104 is the 

same 1⁄2” gypsum wall board characteristic found 

throughout the residence. 

Ceiling: The existing ceiling in Room KR104 is 

the same gypsum board (most likely 1/2” or 5/8” 

thick) characteristic found throughout the 

residence. 

Interior Door: The existing door opening to this 

room is historic wood casing and door (D-4). 

The door is a four paneled wood door with two 

vertical panels above two vertical panels below. 

The door measures 82” high x 36” wide x 13⁄4” 

thick and has historic metal door knob hardware 

and metal butt hinges at the interior face of the 

door.

Moldings: A typical 41⁄4” wood baseboard with a 

3⁄4” base shoe molding painted white are present 

in Room KR103. A wood molding is located at 

the top of the gypsum board walls below the 

historic plaster wall. The historic crown molding 

is 41⁄2” two-piece ovolo, fascia crown mold. The 

door opening in this room has 1” x 21⁄2” wood 

trim at the head and jamb casings with mitered 

corners. The windows have 7/8” x 41⁄4” flat wood 

trim at the head and jamb casings. The jamb trim 

is joined to the head trim with butt joints. The 

moldings in Room KR103 are in sound 

condition and appropriately attached. The 

baseboard (B2) and crown molding (C3) in 

Room KR103 are illustrated in Figure 124 above. 

The same 41⁄4” wood baseboard and 3⁄4” quarterround base molding painted white found in 

Room KR103 is present in Room KR104. A 

wood molding is located at the top of the 

gypsum board walls below the historic plaster 

wall. The historic crown molding is a 4” twopiece ovolo crown mold and picture rail. The 
78 Dry Tortugas Keeper’s Residence HSR 

Figure 135: View of Laundry Room facing south. 

Figure 136: Gouges and holes in the gypsum wall 

board in the Laundry Room. 

windows have 7/8” x 41⁄4” flat wood trim at the 

head and jamb casings. The jamb trim is joined 

to the head trim with butt joints. The baseboard 

(B2) and crown molding (C4) in Room KR104 

are illustrated in Figure 124 above. 

Fixture: There is a single fluorescent light 

fixture located in the center of the ceiling of this 

room. 

Existing Condition: The condition of the finishes 

in Room KR104 is generally sound. Items of 

concern regarding condition include: 

 Peeling and flaking paint at the exterior door 

threshold and door jamb trim. 

 The gypsum wall board is torn at several 

locations at the southeast wall. (Figure 

136) 

Laundry Room (KR105) 

Flooring: The existing flooring in Room KR105 

is the same white and brown 12” x 12” vinyl 

asbestos tile (VAT) characteristic found 

throughout the residence. The floor tile is a 

potential source of asbestos from the materials 

used to create the tile and likely the mastic used 

to secure the tile in place.

Walls: The wall finish in Room KR105 is the 

same 1⁄2” gypsum wall board characteristic found 

throughout the residence. The gypsum board 

has been applied over the plaster of the three 

original walls in this room. The top portion of 

the northeast wall of this room has been cut out 

to allow for the routing of the ductwork for the 

HVAC system that is located within the dropped 

ceiling of the adjacent hallway. 

Ceiling: The existing ceiling in Room KR105 is 

the same gypsum board (most likely 1/2” or 5/8” 

thick) characteristic found throughout the 

residence.

Moldings: There is no baseboard in Room 

KR105. A wood molding is located at the top of 

the gypsum board walls below the historic 

plaster wall. The historic crown molding is a 11⁄4” 

single-piece ovolo crown mold. The window 

opening is this room is has a 7/8” x 41⁄4” flat 

wood trim at the head and jamb casings. The 

jamb trim is joined to the head trim with butt 

joints. The moldings in Room KR105 are in 

sound condition and appropriately attached. 

The historic crown molding (C2) is illustrated in 

Figure 124 above. 

Fixture: There is a single fluorescent light 

fixture located in the center of the ceiling. 
Physical Description 

National Park Service 79 

Figure 137: Plaster damage at west corner of 

bathroom. 

Figure 138: Plaster damage and peeling paint at 

northwest wall or bathroom.

Existing Condition: The condition of the finishes 

in Room KR105 is generally sound. Items noted 

include isolated gouges and holes in the gypsum 

wall board. (Figures 138) 

Bathroom (KR106) 

Flooring: The existing flooring in Room KR106 

is 8” x 8” white ceramic tile. According to Coast 

Guard architectural plans entitled “Crew’s 

Quarters Floor Plan” dated July 19, 1985, vinyl 

asbestos tile (VAT) was installed in the 

bathroom in the mid-1980s as part of the 

rehabilitation of the residence. Given the 

presence of the VAT in other rooms of the 

residence, it is likely that the VAT was installed 

in the bathroom at that time as well, and the 

existing ceramic tile was installed at a later, 

unknown, date. 

Walls: The wall finish in Room KR106 is the 

same 1⁄2” gypsum wall board characteristic found 

throughout the residence. The gypsum board 

has been applied over the plaster walls. As 

described above, sampling of the interior finish 

at the historic plaster in the bathroom revealed 

that the walls were originally painted a pale 

green. 

Ceiling: The existing ceiling in Room KR106 is 

the same gypsum board (most likely 1/2” or 5/8” 

thick) characteristic found throughout the 

residence. 

Interior Door: The existing door to this room 

(D-5) is a hollow-core wood door that measures 

82” high x 34” wide x 13⁄4” thick and has a metal 

door knob and butt hinges.

Moldings : There is no baseboard in Room 

KR106. The historic crown molding is present at 

the joint of the historic plaster wall and ceiling. 

The crown molding is a 11⁄4” single-piece ovolo 

crown mold. The door and window openings in 

this room have 7/8” x 41⁄4” flat wood trim at the 

head and jamb casings. The jamb trim is joined 

to the head trim with butt joints. The moldings 

in Room KR106 are in sound condition and 

appropriately attached. The historic crown 

molding (C2) is illustrated in Figure 124 above. 

Fixture: There is a single fluorescent light 

fixture located in the center of the ceiling. 

Existing Condition: The condition of the finishes 

in Room KR106 is generally poor. Items noted 

include: 

 Torn and missing drywall at east corner of 

bathroom 

 Missing plaster and holes in plaster at west 

corner (Figure 139)

 Missing plaster and holes in plaster at north 

corner

 Cracked and missing plaster at east corner 

 Missing plaster and peeling paint at 

northwest wall (Figure 140) 
80 Dry Tortugas Keeper’s Residence HSR 

Figure 139: Peeling and flaking paint from 

southwest wall above Window 12.

Figure 140: Peeling and flaking paint from plaster 

at southeast wall above Window 8. 

Kitchen/Dining Room (KR107) 

Flooring: The existing flooring in Room KR107 

is the same white and brown 12” x 12” vinyl 

asbestos tile (VAT) characteristic found 

throughout the residence. The floor tile is a 

potential source of asbestos from the materials 

used to create the tile and likely the mastic used 

to secure the tile in place.

Walls: The wall finish in Room KR107 is the 

same 1⁄2” gypsum wall board characteristic 

found throughout the residence. Two metal 

HVAC vents have been cut into the northwest 

wall of this room. One vent is located in the 

kitchen section of the room above the entry 

from the hall. The second vent is located in the 

dining room section of the room. Both vents are 

location approximately 6” from the ceiling. 

Ceiling: The existing ceiling in Room KR107 is 

the same gypsum board (most likely 1/2” or 5/8” 

thick) characteristic found throughout the 

residence.

Moldings: A typical 41⁄4” wood baseboard with 

3⁄4” quarter-round shoe molding painted white is 

present in Room KR107. A wood molding is 

located at the top of the gypsum board walls 

below the historic plaster wall. The historic 

crown molding is present at the joint of the 

historic plaster wall and ceiling. In the kitchen 

section of the room, the crown profile is a 11⁄4” 

single-piece ovolo crown mold. In the dining 

section of the room, the crown profile is a 4 & 

7/8” two-piece ovolo crown mold and picture 

rail. The door opening in the south elevation and 

window openings in this room have 7/8” x 41⁄4” 

flat wood trim at the head and jamb casings. The 

jamb trim is joined to the head trim with butt 

joints. The moldings in Room KR107 are in 

sound condition and appropriately attached. 

The baseboard (B1) and crown molding (C2 and 

C5) are illustrated in Figure 124 above. 

Fixture: There is a single fluorescent light 

fixture located in the center of the ceiling in both 

the kitchen and dining sections of this room. 

Existing Condition: The condition of the finishes 

in Room KR107 is generally good. Items noted 

include: 

 Peeling and flaking paint from plaster in 

kitchen section at southwest wall above 

Window 12 (Figure 141) 

 Peeling and flaking paint from plaster in 

dining section at southeast wall above 

Window 8 (Figure 142) 

 Cracked plaster in dining section at 

southwest wall between Windows 6 and 7 

Utilities 

Electrical System: As noted in the Chronology of 

Development and Use section above, the 

residence has undergone several updates of its 

electrical system. Most recently, between 1985 

and 1989, the building was rewired, the electrical 
Physical Description 

National Park Service 81 

Figure 141: Concrete “pull” hatch on the south 

side of the residence. 

Figure 142: Surface-mounted distribution panel on 

northwest wall of Room KR105. 

panel and fire alarm replaced, and fluorescent 

interior fixtures and incandescent exterior 

fixtures were installed.

Currently, electrical power is provided to the 

Keeper’s Residence by the photovoltaic (PV) 

system installed by the National Park Service in 

2002. Prior to installation of the PV system, 

electricity was produced by two diesel-powered 

generators. Fuel for these generators was 

provided by the USCG, however due to the cost 

and hazards associated with delivering fuel to 

the island, the Coast Guard installed solar panels 

on the tower to power the Lighthouse. Shortly 

thereafter, the National Park Service installed an 

expanded PV system to service all of the 

structures of the Light Station. 

Power for the Light Station utility systems and 

structures is generated by the large photovoltaic 

array located west of the tower. A bank of 

batteries, located in the rear addition of the oil 

house stores power from the system for use at 

night and for times when the array cannot 

provide enough current for demand during the 

day. The system’s controllers and conversion 

panels are located on the south wall of the oil 

house and the distribution load centers are 

located in the south addition. From here 

electricity is delivered to the Light Station 

structures through underground conduits. 

The electrical service for the Keeper’s Residence 

is routed underground through a concrete “pull” 

hatch on the southwest side of the residence and 

into the crawlspace of the residence. (Figure 

143) The wiring is then routed through the 

flooring to the surface-mounted distribution 

panel on the northwest wall of Room KR105. 

(Figure 144) 

The house wiring runs from the distribution 

panel through the ceiling of Room KR105 into 

the attic. The wiring to and from the distribution 

panel is housed in gray plastic conduit. (Figure 

145) 

The wiring in the attic is sheathed in white 

plastic and attached to the framing with plastic 

fasteners as it is routed to the individual rooms. 

In addition, an older generation of fabric-clad 

wiring (in black sheathing) is present in the attic. 

(Figure 146) 

The distribution panel indicates 120/240 V 

service and is a 16-circuit panel with a 125A 

main circuit breaker. The 16 circuits are: 

Ckt. #1 Birdbath (20-10kA) 

Ckt. #2 Microwave/Sink (20-10kA) 

Ckt. #3 Master Bedroom (20-10kA) 

Ckt. #4 Back Porch/Kitchen (20-10kA) 
82 Dry Tortugas Keeper’s Residence HSR 

Figure 143: Conduit from distribution panel to the 

attic.

Figure 144: White –sheathed wiring in the attic 

and older generation of fabric-clad wiring (in black 

sheathing). 

Ckt. #5 Empty 

Ckt. #6 Refrigerator/Stove (20-10kA) 

Ckt. #7 Indoor AC Unit (20-10kA) 

Ckt. #8 Dining Room/Bedroom (20-10kA) 

Ckt. #9 Empty 

Ckt. #10 Dryer (20-10kA) 

Ckt. #11 Outdoor AC Unit (20-10kA) 

Ckt. #12 Living Room/Front Porch (20-10kA) 

Ckt. #13 Empty 

Ckt. #14 Hot Water Heater (30-10AIC) 

Ckt. #15 Empty 

Ckt. #16 Empty 

There are 24 electrical outlets, ten switches, six 

identical interior overhead fluorescent light 

fixtures, and two exterior incandescent light 

fixtures. Descriptions of electrical system 

components per room are summarized below. 

 The living room (KR101) has six outlets, a 

double switch, and a double-tube 

fluorescent light fixture mounted in the 

ceiling. (Figure 147) 

 The hallway (KR102) has two outlets, two 

single switches, and an electrical box (but no 

fixture) mounted in the ceiling. 

 The bedroom KR103) has four outlets, a 

single switch, and a double-tube fluorescent 

light fixture mounted in the ceiling. 

 The laundry room (KR105) has two outlets, 

a single switch, and a double-tube 

fluorescent light fixture mounted in the 

ceiling. 

 The bathroom (KR106) has one outlet, a 

single switch, and a double-tube fluorescent 

light fixture mounted in the ceiling. 

 The kitchen portion of Room KR107 has 

four outlets, two single switches, a double 

switch, and a double-tube fluorescent light 

fixture mounted in the ceiling. 

 The dining portion of Room KR107 has five 

outlets, a double switch, and a two-tube 

fluorescent light fixture mounted in the 

ceiling. 

 The back porch has a modern metal 

electrical box mounted in the ceiling with a 

porcelain fixture, but no light bulb. There is 

an additional square cut-out in the back 

porch ceiling with existing electrical wiring 

visible. The side porch light fixture is 

controlled by a switch in the kitchen just 

inside the side door. 

 The front porch has a square cut-out in the 

ceiling for a fixture, but no electrical box, 

wiring, fixture, or bulb is present. 
Physical Description 

National Park Service 83 

Figure 145: Double-tube fluorescent light fixture 

mounted in the ceiling. 

Figure 146: Two steel gas supply tanks located at 

the west elevation. 

Figure 147: Propane tanks exhibit rust and 

corrosion. 

Existing Condition: The photovoltaic array has 

an anticipated useful life of 20 years, which 

leaves a minimum of 13 years before it will need 

to be replaced. However, the lifespan of the 

individual components of the system and the 

batteries range from eight to ten years. Regular 

maintenance of the system is required primarily 

due to the effects of the environment on 

individual system components. 

The existing system has sufficient capacity to 

service the demand required by a general level of 

use. However, at certain times when the housing 

units are filled and demand for cooling is high 

the system is required to operate near its 

capacity. It has been suggested that better 

educating those that use the housing facilities 

about the limits of the system and energy saving 

measures would help to mediate these periods of 

peak demand and reduce strain on the system. 

The electrical system of the Keeper’s Residence 

is generally in sound condition. The plastic 

conduit, plastic sheathed wiring, distribution 

panel, and electrical switches, fixtures and 

outlets appear intact and in operable condition. 

However, the older generation of fabric-clad 

wiring shows signs of wear and the sheathing is 

frayed as viewed from the attic. 

Gas: The Keeper’s Residence has a propane gas 

supply system to provide fuel for cooking. Two 

steel gas supply tanks are located at the exterior 

of the northwest elevation adjacent to the 

kitchen. (Figure 148) The steel gas supply pipe 

penetrates the northwest foundation wall and 

extends southeast along the underside of the 

floor joists to a point where it turns up to 

connect to the oven in the kitchen. 

Existing Condition: The gas system is in operable 

condition, however, the gas tanks themselves 

exhibit rust and corrosion. The roof of the shed 

covering the tanks is also deteriorated, with 

missing roofing shingles. (Figure 149) 

HVAC: The Keeper’s Residence was historically 

not air-conditioned. Air conditioning was 

installed in the residence in 1969. The system 

consisted of five (5) window-mounted air 

conditioning units, a ceiling exhaust fan, and 

glass fiber blanket-type insulation. Of the five 
84 Dry Tortugas Keeper’s Residence HSR 

Figure 148: Trane air handler located in the 

laundry room (KR105). 

Figure 149: Trane air compressor located on the 

side porch. 

units installed, four were 13,000 BTU units and 

the fifth was an 8,000 BTU unit. 71 

As noted in the Chronology of Development and 

Use section of this report, an HVAC system was 

installed in the residence in 2002. During a 

project to convert the power source for the 

 

71 Floor Plan by the U.s. Coast Guard Civil Engineering Division: 

Barracks Building Air conditioning project, Dry Tortugas Light 

Station; Dated April 10, 1969. 

Light Station from diesel generators to 

photovoltaic electric generation and battery 

storage, a centralized air handling unit and two 

air compressors were installed at the residence. 

The HVAC system has an air handler located in 

the laundry room (KR105). The Trane 

equipment (model # TWE031E13FB1; serial # 

Z501SXK1V) is a 200-230 volt, 4.3 amp unit that 

was manufactured in December 2001. (Figure 

150) 

Two Trane air compressors are associated with 

the residence. A Trane XR13 (model # 

2TTR3018A1000AA; serial # 8374L8E3F) 

manufactured in September 2008 is located on 

the back porch. (Figure 151) 

A Trane XL16i (model # 4TTX6048B1000BA; 

serial # 7311PBC1F) manufactured in July 2007 

is located at the northeast side of the residence. 

(Figure 152) 

During this project, the ceiling in the hall was 

lowered to accommodate the ductwork. (Figure 

153) 

The ductwork runs the length of the hall 

encased in the dropped ceiling and provides air 

supply to each adjacent room through vents at 

the upper portion of the common walls. (Figure 

154) 

Existing Condition: The HVAC system is in 

reliable operating condition. The air 

conditioning function of the system was in 

working order during the time of inspection. 

The air handler unit and compressors appear to 

be intact. The portion of ductwork visible from 

the interior of the residence and within the 

dropped ceiling is in sound condition, with no 

holes or tears evident. 

Plumbing System: According to the 1920 

specifications for the Keeper’s Residence, a 

plumbing system was installed in the building at 

the time of construction. The specifications 

outline the following requirements for the 

original plumbing system: 

 Rough in all necessary connections for 

kitchen sink, bath tub, lavatory and water 

closet. 
Physical Description 

National Park Service 85 

Figure 150: Trane air compressor located at the 

north elevation behind the walk boards. 

Figure 151: View of dropped ceiling and ductwork 

in the hall. 

Figure 152: Typical metal vent in rooms. 

 Two separate lines of 3⁄4 inch galvanized 

wrought iron pipe to extend from sink, bath 

tub and lavatory, connecting into two 

common runs of 1 inch galvanized wrought 

 iron pipe which shall extend beyond the 

foundations of dwelling not more than six 

feet. 

 A 3 inch cast iron pipe, with proper 

connections for waste pipes from sink, 

lavatory, bath tub and water closet, shall be 

suspended securely from the bottom of floor 

joists and extend through foundation wall 

and terminate with Y-branch and cleanout 

plug. 

 The plumbing fixtures were bid separately 

and were to be installed and connected to 

waster and supply pipes. 

 One cast iron roll rim kitchen sink, 36 by 20 

inches, integral back with hollow space for 

pipe connections 

 One rectangular pattern, 20 by 18 inch, 

enameled iron, integral back roll rim 

lavatory, with oval bowl, apron, and open 

integral overflow 

 One 5 foot, enameled, cast iron, roll rim bath 

tub supported on cast-iron ball feet 

 One vitreous ware, flushing rim, siphon jet 

water closet, with pedestal base and molded 

in trap, provided with substantial, well 

finished seat and cover and low-down, 

vitreous ware flushing tank 

 Faucets are to be standard grade, well 

finished nickel plated of Fuller type 

Visual inspection reveals that additional 

plumbing lines and fixtures have been installed, 

although the date if installation is not known. 

These more recent plumbing lines are 16” PVC 

piping located under the house in the crawlspace 

and on the northeast side of the residence 

adjacent to the bathroom. (Figure 155) 

Remnants of the older generation of iron piping 

are still in place in the crawlspace as well. (Figure 

156) 

Water is supplied to the residence via a reverse 

osmosis potable water system. From the holding 
86 Dry Tortugas Keeper’s Residence HSR 

Figure 153: View of PVC plumbing lines located in 

the crawlspace. 

Figure 154: View of older generation iron 

plumbing piping. 

Figure 155: Existing sink in kitchen (KR107). 

tanks located in the south Oil House addition 

water is pumped to the residence via an 

underground PVC supply line. Hot water is 

provided by a passive hot water heater located to 

the north of the residence. 

Plumbing fixtures have been installed in the 

kitchen, laundry room, and bathroom. The 

fixture in the kitchen is a stainless steel double 

sink. The 1921 architectural plans show that the 

original sink was installed at the northwest (rear) 

wall of the kitchen. The existing sink is located 

at the southeast wall. (Figure 157) 

A plumbing connection is provided in the 

laundry room for a washing machine that is part 

of a stacked system. (Figure 158) 

There are three plumbing system fixtures in the 

bathroom, including a sink/lavatory, molded 

plastic shower, and toilet. The 1921 architectural 

plans show the original sequence of fixtures in 

the bathroom of lavatory and water closet along 

the left side of the room and tub at the northeast 

wall. The existing sequence of fixtures is sink, 

molded-plastic shower, and toilet along the left 

side of the room. (Figure 159) 

Existing Condition: The plumbing system is 

generally in reliable operating condition. No 

signs of active or past leaking from the piping 

were observed under the residence at the time of 

inspection. 

Summary of Conditions 

The following is a summary of the condition 

issues observed during inspection of the 

Keeper’s Residence. 

Structural 

 Localized mortar loss and joint cracking at 

foundation walls and piers. 

 Floor framing exhibits no sign of settlement 

or deterioration. 

 Roof framing exhibits no signs of significant 

past or active moisture damage. Existing 

open attic vent is potential source of 

moisture infiltration. Fasteners appear in 

generally good condition. 
Physical Description 

National Park Service 87 

 Although no active termites where observed, 

isolated areas of damage from previous 

termite activity are present. 

Exterior 

 Existing composition asphalt shingle roofing 

exhibits no signs of moisture infiltration, 

though several individual shingles are torn 

or missing. 

 Gutters and downspouts, which were 

original features of the residence, have been 

removed. 

 The eave and cornice exhibit general 

weathering and deterioration of painted 

finish to wood elements; metal flashing and 

nails are rusted though still functional; and 

localized damage to the wood molding and 

screening at the eave soffit. 

 Moderate erosion of mortar and face brick 

at exterior walls due to weathering. Several 

areas of deteriorated masonry have been 

repaired with replacement brick and mortar 

not matching historic materials. 

 Extensive localized mortar joint and 

masonry cracking at exterior masonry walls 

due to jacking from corrosion and 

associated expansion of the steel lintels 

embedded in masonry walls. 

 Localized damage to mortar joints, brick, 

and concrete caps at front porch piers due 

to corrosion and expansion of embedded 

anchors. 

 General weathering and deterioration of the 

painted finish of front porch columns, eave 

and cornice and side porch posts, eave and 

cornice. 

 Multiple layers of paint build-up and 

chipping and flaking of the outer layers at 

front and side porch ceilings and flooring. 

 The existing non-historic front porch railing 

is not compatible with the historic character 

of the building. Front porch balustrade at 

south corner of house is separating and face 

board is detached from wall. 

 Front and rear porch floor boards are 

damaged at their outside edges, including 

broken boards, split & cracking board ends, 

joint separation between boards, and rot 

damage to boards. 

 Localized damage to wood molding and 

screening at the eave soffit at the front and 

side porches. 

 Separation at joint between cheek walls and 

cement steps at front porch stairs due to 

settlement of stairs. 

 Finish on the exterior face of all doors is 

slightly weathered due to exposure to the 

Figure 156: Existing washing machine and dryer in 

the laundry room (KR105). 

Figure 157: Plumbing fixtures in the bathroom 

(KR106), including sink, shower and toilet (beyond 

shower). 
88 Dry Tortugas Keeper’s Residence HSR 

elements; heads of nails used to fasten 

weather stripping to the secondary front 

door are corroded. 

 Removal of historic doors and modification 

of primary entrance surround. 

 Steel lintels above the door frames show 

minor corrosion. 

 Paint finish on the threshold at the primary 

front door is chipped and cracked at select 

locations. 

 Aluminum tracks for hurricane shutters 

installed at the window heads and sills have 

caused cracking and chipping of the brick 

masonry and concrete sills. 

 Removal of historic louvered wood shutters. 

Interior 

 Tile flooring is uneven and in Room KR101, 

most likely due to poor underlayment 

and/or moisture infiltration from below. 

 Diagonal hairline cracks in plaster wall at 

east corner of Room KR101, south corner of 

Room KR103, and southwest wall between 

Windows 6 and 7 in room KR107. These 

cracks appear to be dormant. 

 Peeling and flaking paint from plaster at 

southwest wall above Window 12 and 

southeast wall above Window 8 in Room 

KR107; at the southeast wall at its juncture 

with the ceiling in Room KR102; and at the 

southwest wall along the door frame in 

Room KR103. 

 Isolated gouges and holes in the gypsum wall 

board in Room KR105 and at the east corner 

in Room KR106. 

 Missing plaster and holes in plaster walls at 

west corner, north corner, east corner, and 

northwest wall of Room KR106; cracked 

plaster in southwest wall between Windows 

6 and 7 of dining section of Room KR107. 

 Separation/minor crack between drywall 

panels at ceiling of dining section of Room 

KR107. 

Utilities

 The electrical system appears in sound 

condition. The plastic conduit, plastic 

sheathed wiring, distribution panel, and 

electrical switches, fixtures and outlets 

appear intact and in operable condition. The 

older generation of fabric-clad wiring shows 

signs of wear and the sheathing is frayed as 

viewed from the attic. 

 The gas system is in operable condition, 

however, the gas tanks themselves exhibit 

rust and corrosion. 

 The HVAC system is in reliable operating 

condition. The air conditioning function of 

the system was in working order during the 

time of inspection. The air handler unit and 

compressors appear to be intact. The 

portion of ductwork visible from the interior 

of the residence and within the dropped 

ceiling is in sound condition, with no holes 

evident. 

 The plumbing system is generally in reliable 

operating condition. No signs of active or 

past leaking from the piping were observed 

under the residence at the time of 

inspection. However, the older generation 

of wrought and cast iron piping located in 

the crawlspace exhibits signs of corrosion. 
National Park Service 89 

Requirements for Treatment 

and Use 

The treatment and use of the Dry Tortugas 

Keeper’s Residence must be considered within a 

framework of applicable laws, policies and 

agreements. These various mandates govern a 

wide range of management issues beyond the 

preservation, protection and interpretation of 

the Park’s cultural resources. They extend to 

issues of visitor and staff use, safety, and 

universal accessibility among others. Because the 

National Park Service has agreed to reserve a 

room in the Keeper’s Residence for the exclusive 

use of U.S. Coast Guard personnel and provide 

water and power to the residence under a 

cooperative agreement between the two 

agencies, treatment and management will in part 

be bound by this and future agreements between 

the NPS and USCG. 

The National Historic Preservation 

Act 

Section 106 of the National Historic 

Preservation Act mandates that Federal 

agencies, including the National Park Service 

take into account the effects of their actions on 

properties listed or eligible for listing in the 

National Register of Historic Places. The goal of 

this directive is to encourage agencies to avoid 

or minimize adverse impacts to cultural 

resources and to make sure preservation is fully 

considered as part of the planning process. The 

Section 106 process also requires consultation 

with parties outside the National Park Service 

that may have an interest in the property. 

In 1995, in an effort to expedite the review 

process, a programmatic agreement was made 

between the Advisory Council and the NPS that 

allows for programmatic exclusion of some 

activities from the full Section 106 review 

process. These excluded activities are limited to 

routine repairs and maintenance that do not 

alter the appearance of the historic structure or 

involve widespread or total replacement of 

historic features or materials. 

Accessibility 

The National Park Service is committed to 

providing persons with disabilities the highest 

feasible level of physical access to historic 

properties. 

The Architectural Barriers Act of 1968, the 

Rehabilitation Act of 1973 and the Americans 

with Disabilities Act of 1990 set forth the federal 

mandate for making buildings and facilities more 

accessible. The guidelines that accompany these 

Acts as well as the Uniform Federal Accessibility 

Standards (UFAS; 41 CFR 19.6; 49 FR 31528) 

provide design direction for accessibility 

modifications to historic structures in the 

national park system. With regard to outdoor 

developed areas such as trails, beaches and 

picnic and camping areas, the National Park 

Service has adopted the U.S. Access Board’s 

Outdoor Environments guidelines. 

Given that full compliance with these mandates 

in many cases would require alteration of 

significant features of a historic property, 

provisions have been made within the Acts for 

achieving alternative means of compliance. 

Given that the Keeper’s Residence will be used 

as housing, options for providing full 

accessibility should be explored. 

In addition to building and site related 

accessibility issues, the primary challenge at the 

Dry Tortugas Light Station is accessing the site 

itself. Although at least one of the commercial 

vessels used to transport visitors to the park is 

accessible and equipped to accommodate a 

wheelchair, currently the only debarkation point 

within the park is on Garden Key. There are 

currently no public docking facilities provided at 
90 Dry Tortugas Keeper’s Residence HSR 

Loggerhead Key. Thus there is currently no 

accessible route that could bring a mobilityimpaired visitor to Loggerhead Key or the Light 

Station. If accessible access to the island could 

be established, improvements to the wharf and 

walkways would have to be completed to access 

the Light Station itself. Due to the topography of 

the Key, providing an accessible route from the 

dock to the Light Station may require significant 

alteration of the historic landscape. 

Recognizing its obligation to make the Park 

accessible to the widest audience possible, the 

Park has outlined its management direction in 

the General Management Plan Amendment. 

Make visitor and management facilities as 

accessible as practicable, depending on the 

nature of the area and of the facility, to persons 

with visual, hearing, mobility, and mental 

impairments. Strive to provide the highest level 

of accessibility possible to facilities, programs, 

and services consistent with the nature of the 

area, the conservation of resources and the 

mandate to provide a quality experience for 

everyone. 

Meet accessibility standards on visitor 

transportation vessels and aircraft with the limits 

of marine and aircraft design and safety 

requirements. Work with organizations that 

encourage and enable use of the park areas by 

special populations, which will increase 

awareness o f the needs of these populations and 

help to ensure that potential visitors with 

particular needs are aware of the opportunities 

offered at the Dry Tortugas. 

International Building Code 

As a matter of policy, the National Park Service 

has adopted the International Building Code 

which establishes minimum regulations for the 

design and installation of building systems with 

an emphasis on preserving public health and 

safety. Its requirements are applicable to both 

new construction and the repair and alteration 

of existing buildings. 

Full compliance with IBC requirements is not 

mandatory for historic buildings where there is 

no threat to life safety. 

3407.1 Historic Buildings: The provisions 

of this code related to the construction, 

repair, alteration, addition, restoration 

and movement of structures, and change 

of occupancy shall not be mandatory for 

historic buildings where such buildings are 

judged by the building official to not 

constitute a distinct life safety hazard 

[emphasis added]. 

Alternatives to full code compliance can be 

sought where compliance would needlessly 

compromise the integrity of the historic 

building. 

DO #58 and NFPA Code 914 

Among many other issues, the National Park 

Service Management Policies address the 

protection of historic resources against fire. 

Section 5.3.1.2 of the policy document states 

that: 

In the preservation of historic structures and 

museum and library collections, every attempt 

will be made to comply with national building 

and fire codes. When these cannot be met 

without significantly impairing a structure’s 

integrity and character, management and use of 

the structure will be modified to minimize 

potential hazards rather than modifying the 

structure itself. 

NFPA Code 914, “Fire Protection of Historic 

Structures” has been adopted by the National 

Park Service. 

Since the Keeper’s Residence is to be used for 

housing, the addition of a sprinkler system to 

provide fire suppression is recommended. 

Further assessment should be conducted to 

determine the feasibility of installing a sprinkler 

system in the building. If it’s not feasible, 

alternative means of providing fire protection 

should be explored. 

The Secretary of the Interior’s 

Standards 

Treatment of historic resources associated with 

the Light Station is to be guided by The 

Secretary of the Interior’s Standards for the 

Treatment of Historic Properties. These 
Requirements for Treatment and Use 

National Park Service 91 

standards provide a framework for planning and 

implementing responsible preservation practices 

and ensuring there is a philosophical consistency 

to the work. A series of guidelines have been 

developed to accompany the standards and 

assist with their interpretation. 

Additionally, the Preservation Briefs published 

by the National Park Service provide technical 

guidance for the appropriate treatment of a 

variety of materials, features and conditions 

found in historic buildings. 

Cooperative Agreements with 

USCG 

When Dry Tortugas National Park was 

established in 1992 the U.S. Coast Guard 

determined the facilities on Loggerhead Key to 

be “excess to its needs” and transferred the 

property (the entire key) to the National Park 

Service. The transfer of property excluded the 

Lighthouse with the stipulation that the USCG 

would continue to “maintain and utilize” the 

structure for its own purposes, primarily as an 

active aid to navigation. 

In 2007 the USCG and National Park Service 

entered into a cooperative agreement regarding 

the use of facilities and utilities on Loggerhead 

Key. This agreement requires the NPS to reserve 

a room within the Keeper’s Residence for the 

exclusive use of USCG personnel and provide 

water and power to the building. Among other 

minor items the USCG agreed to provide 

propane and gasoline storage tanks to the island 

and to refrain from making modifications to the 

Keeper’s Residence with the exception of 

rehabilitating the rainwater collection system. 

In 2008 a Memorandum of Agreement was 

prepared between the USCG and the NPS that 

establishes the parameters for the formal 

transfer of ownership of the Lighthouse to the 

NPS. Transfer of the Lighthouse is contingent 

upon several requirements, one being 

completion of this Historic Structure Report. 

Upon transfer of the Lighthouse the USCG will 

retain ownership of the lens and associated 

equipment and require continued access to the 

Lighthouse to maintain this equipment. 
National Park Service 92 
National Park Service 93 

Ultimate Treatment and Use

Use 

The Dry Tortugas Light Station has served 

continuously as an aid to navigation since its 

light was first lit in 1858. Likewise, the 

Keeper’s Residence has continuously served as 

housing for Lighthouse Board, USCG and 

NPS personnel and visitors to the Key for 

more than 80 years. 

As discussed in the previous section, current 

cooperative agreements with the USCG affect 

the use of the Keeper’s Residence, requiring at 

least a portion of the building to be used for 

housing. Under these agreements, the NPS has 

agreed to maintain a room in the Keeper’s 

Residence for the exclusive use of USCG 

personnel when on the Key. In addition, the 

agreements stipulate that the USCG will not 

make any modifications to the building except 

to rehabilitate the rainwater collection system. 

Further, the Park’s General Management Plan 

Amendment (GMPA) calls for the resources of 

the Light Station to be preserved and 

protected according to the Park’s authorizing 

legislation and also that they be managed to 

support operational needs and visitor use. An 

important outcome of the GMPA has been the 

establishment of management zones that 

prescribe the types and levels of visitor use and 

the amount of manipulation of the natural or 

cultural setting that is appropriate for different 

areas of the Park. 

The GMPA has addressed treatment and use 

of the Light Station resources through the 

creation of a Historic Preservation/Adaptive 

Use (HP/AU) Management Zone. One of four 

management zones established within the 

Park, the HP/AU Zone applies to those areas 

that contain historic and cultural resources 

and where the visitor experience will be 

primarily focused on educational and 

interpretive opportunities. 

Two management zones have been applied to 

Loggerhead Key. The HP/AU Zone 

encompass the resources of the Light Station 

in the center of the Key with the remainder of 

the island falling within a Research Natural 

Area Zone. 

The parameters established by the GMPA for 

Loggerhead Key, limit the number of visitors 

that can be on the island to 24 (12 originating 

from the commercial carriers and 12 from 

private vessels). This number has been 

established as an initial baseline that may be 

adjusted in the future pending the results of a 

monitoring program and the completion of 

the re-vegetation project. 

Permissible uses within Loggerhead Key’s 

HP/AU zone include unrestricted picnicking, 

hiking, and exploring. However, the GMPA 

currently restricts visitor access to the 

buildings until such time as the structures can 

be made safe and the appropriate programs 

are in place to support this level of use. 

Since the transfer of Loggerhead Key and the 

Light Station to the National Park Service in 

1992, public visitation to the Key has been 

limited. Existing concession agreements do 

not include provisions for transporting visitors 

from Garden Key to Loggerhead Key. 

Therefore the site has only been accessible to 

those reaching the island by private vessel. 

Looking forward however, the Park is 

exploring ways that it can improve public 

access to the Key through renewed concession 

agreements. In addition, consideration is being 

given to utilizing the Light Station resources as 

a “base of operations” for an expanded 

program of scientific investigation and 

research associated with the areas status as a 

Research Natural Area (RNA). This 
94 Dry Tortugas Keeper’s Residence HSR 

designation covers a 46 square mile area that is 

designated as a marine reserve designed to 

restore ecological integrity and capacity for 

self-renewal by minimizing human 

disturbance. The RNA complements the 

adjacent Tortugas Ecological Reserve of the 

Florida Keys National Marine Sanctuary 

(FKNMS). Together the RNA and the larger 

Tortugas Ecological Reserve will help to 

ensure the success of both marine and 

terrestrial ecosystems while offering 

outstanding opportunities for scientific 

research and public education. 

Under these scenarios, the use of the Keeper’s 

Residence is not anticipated to change, 

however its intensity of use may be increased. 

The Keeper’s Residence will continue to serve 

as residential housing for Coast Guard and 

National Park Service personnel as well as 

contractors and researchers while visiting the 

Key. 

The Keeper’s Residence should be interpreted 

as a historic component of the Light Station 

and a good example of an early-twentieth 

century light keeper’s residence. While the 

exterior of the Keeper’s Residence can 

contribute to the interpretive experience of 

visitors to the Light Station, NPS personnel 

have indicated that the interior of the 

residence will be used for housing and will 

thus not be open to visitation by the general 

public. 

Building Fabric 

While the Keeper’s Residence has received 

modifications over time, the building retains a 

majority of its historic integrity. Some of the 

existing building elements date to the 

building’s construction while others have been 

replaced with non-historic materials. The 

Keeper’s Residence is a bungalow style 

structure with a masonry wall structure and 

three door and fifteen window openings. The 

building has a wood frame hipped roof 

structure with asphalt shingle roofing. There 

have been changes to these elements over 

time, including repair and replacement of 

materials that have deteriorated due to the 

extreme weather conditions at the Key or that 

have been upgraded due to technological 

improvements in materials (such as the 

composition asphalt roofing shingles) and 

systems (installation of HVAC, electrical and 

passive solar systems). 

The building’s load-bearing brick masonry 

walls remain intact though they have been 

repaired and repointed over time. The existing 

six-over-six double-hung windows in the 

residence were installed in 2003, replacing 

non-historic windows installed at an earlier 

date. The size and pane configuration of the 

existing windows accurately replicate that of 

the windows that were present in the 

residence historically. The wood shutters that 

were originally installed over the windows 

have been removed at an unknown date and 

metal hurricane shutters and tracks installed 

over the windows. In addition, the historic 

exterior doors and the entry surround at the 

front door have been removed and replaced 

with non-historic components. While the 

asphalt roofing is not historic to the residence, 

the wood frame roof structure is historic and 

intact. 

The interior of the residence has experienced 

changes in its floor plan and finishes. The floor 

plan was first altered in the early 1950s, and 

twice again in the 1980s. Also in the 1980s, 

new flooring and baseboards as well as 

gypsum board over the plaster walls and wood 

ceilings were installed. The residence 

underwent several changes to its mechanical 

systems. The plumbing system was updated in 

the early 1950’s and a fire detection system 

was added in the early 1970’s. The building 

was rewired and new electrical outlets and 

fixtures were added during the 1980s. 

Centralized air conditioning and high 

efficiency appliances were added to the 

residence in 2002. 

Recommended Ultimate 

Treatment and Use 

It is recommended that the ultimate treatment 

and use of the Light Station resources remain 

consistent with the guidelines established in 

the GMPA for the HP/AU Management Zone. 

As the name implies, this zone calls for the 

preservation, protection and interpretation of 
Ultimate Treatment and Use 

National Park Service 95 

cultural resources yet recognizes the need to 

adaptively use these resources to 

accommodate critical functions, such as 

housing, sheltering essential equipment and 

utility components and the maintenance of the 

lighthouse optic as an active navigational aid. 

The Recommended Ultimate Treatment for 

the Keeper’s Residence is restoration of the 

exterior character of the building to its historic 

appearance to enhance interpretive 

programming and rehabilitation of the interior 

spaces and finishes to accommodate the needs 

for continued use as housing. 

The historic character of the building’s 

exterior appearance should be maintained and 

restored where appropriate during future 

rehabilitation projects to correct condition 

issues. Exterior components that should be 

restored include the exterior doors and 

primary entry sidelights, wood shutters, wood 

lattice at rear porch, and fencing around site. 

Given that the Keeper’s Residence will 

continue to be used to provide housing to 

personnel at the Light Station, the interior 

should continue to be adaptable to the needs 

of modern living while preserving existing 

historic character. 

This treatment approach would maintain and 

restore the exterior of the building to the 

period of its original construction, and thereby 

facilitate interpretation to that period of 

modernization at the Light Station in the early 

1920’s. This approach would maintain the 

existing interior character and allow for 

necessary material and system upgrades to 

accommodate residential use of the building. 

This approach would also allow for future 

interpretation of the evolution of changes to 

the interior of the building. 

This approach has the following advantages: 

• Addresses deferred maintenance and 

needed repairs to prevent further 

deterioration or loss of historic fabric 

• Preserves in place for interpretation, 

building fabric from a broad spectrum 

of the building’s history. 

• Removes modifications made during 

the recent past that are not in keeping 

with the building’s historic character 

(such as non-historic doors). 

• Restores character defining features 

such as the exterior doors and 

louvered wood shutters that were 

historically present on the building. 

This approach has the following 

disadvantages: 

• Misses the opportunity to restore and 

interpret the interior floor plan and 

finishes, such as the plaster wall 

finishes, wall finishes and wood 

ceiling finishes. 

 
96 Dry Tortugas Keeper’s Residence HSR 
National Park Service 97 

Alternatives for Treatment 

and Use 

Use 

The Dry Tortugas Keeper’s Residence was 

designed for the single purpose of providing 

residential housing for the principal keeper 

and family while stationed at the Light Station. 

While the Keeper’s Residence no longer 

provides housing for a keeper, it continues to 

be used for the purpose of housing for visitors 

to the Light Station. 

While the intent of the NPS is to continue to 

use the Keeper’s Residence to provide housing 

for staff and visitors to the Key, the building 

could be adaptively used for other purposes in 

the future. Consideration for potential 

alternative uses could include adapting the 

building as a visitor center should the level of 

visitation rise to a point where a visitor center 

is warranted and/or the need for residential 

housing on the Key is reduced. 

Treatment 

The proposed ultimate treatment 

recommends restoration of the exterior of the 

Keeper’s Residence to its 1920’s appearance. 

Potential exterior elements for restoration 

include the exterior doors and entry sidelights, 

wood shutters, wood lattice at rear porch, and 

fencing around site. 

An alternative treatment approach would be to 

restore both the exterior and interior of the 

building. While this approach would best 

facilitate full interpretation of the building and 

its use as a Keeper’s Residence and would not 

necessarily preclude it from being used for 

housing, it would not best serve the ongoing 

need for the Keeper’s Residence to provide 

comfortable and functional housing for 

visitors to the island. 

Another alternative treatment approach would 

be to restore the exterior of the building to its 

historic appearance and rehabilitate the 

interior while restoring certain interior 

character defining features. Through this 

approach, several non-historic interior 

finishes could be removed to recapture the 

historic finishes of the residence, including the 

vinyl asbestos tile and carpeting, gypsum 

board wall and ceiling finishes. This 

alternative approach is similar to the 

recommended treatment and restoration of 

these select interior material features could be 

pursued in future rehabilitation projects as the 

existing non-historic materials deteriorate or 

are removed. 

Another alternative treatment approach would 

be to preserve all existing fabric regardless of 

its aesthetic character in order to represent 

and interpret the full evolution of changes to 

the Keeper’s Residence throughout its entire 

history. 

 
98 Dry Tortugas Keeper’s Residence HSR 
 National Park Service 99 

Recommendations for Treatment 

and Use 

The 1922 Keeper’s Residence at the Dry 

Tortugas Light Station was well-designed, 

well-constructed, and generally wellmaintained. The building has remained in 

sound condition throughout periods of 

oversight by the Bureau of Lighthouses, U.S. 

Coast Guard, and the National Park Service. 

While the building has undergone interior 

plan and material changes over time, it retains 

its historic character as a residence for keepers 

and their family members and later visitors to 

the Light Station. 

Foundation 

While the house foundation walls show no 

signs of significant deterioration, the porch 

foundation walls exhibit loss of mortar in the 

masonry joints, past repointing with mortar 

that does not match the historic mortar, and 

weathering and spalling of brick. 

Recommendation: Where its removal will not 

result in damage to the brick, it is 

recommended that incompatible replacement 

mortars be removed, damaged brick replaced, 

and deteriorated joints repointed. All 

deteriorated joints with a loss of mortar to a 

depth of more than 5/8” should be repointed. 

Based on inspections made during the 

development of the HSR, it is estimated that 

approximately 35% of the porch foundation 

walls should be repointed. 

Formulate repointing mortar to match as 

closely as is practicable, the composition of the 

original mortar. The mortar analysis identified 

ordinary gray Portland cement as the original 

binder with natural carbonate sand at a 

component ratio of 1:2.4. Given that modern 

Portland cements differ in character from 

their early-twentieth century counterparts it is 

recommended that the repair mix be tempered 

with lime. Consideration should also be given 

to using a Type II or Type V (sulfate resistant) 

Portland cement given the salt laden 

environment. Mock-ups should be prepared 

to ensure the most accurate match possible 

between the replacement and historic mortars. 

Brick to be replaced should also match 

existing brick in size, color, and texture. 

Roof 

The roof of the Keeper’s Residence is 

performing well and is not currently in need of 

replacement. However, it is recommended 

that the few missing and damaged asphalt 

shingles be replaced with shingles matching 

the existing roofing material. In addition, the 

existing attic vent that is currently open to the 

elements should be protected so that moisture 

cannot infiltrate into the attic. As the roofing 

materials deteriorate and replacement 

becomes necessary, consideration should be 

given to installing a roofing material that 

matches the hexagonal pattern of the original 

roof. 

Recommendation: It is recommended that 

the rusted metal drip edge and nails be 

replaced, damaged wood quarter-round and 

soffit screening be replaced, gap in the drip 

edge at the south elevation be repaired, gap in 

the frieze board at the east corner be repaired, 

and the weathered painted finish be repainted 

white based on results of the Materials 

Analysis. 

Gutters & Downspouts 

While the residence originally had galvanized 

metal gutters and downspouts, PVC gutters 

and downspouts were installed in 1989. There 

are currently no gutters and only a single 
100 Dry Tortugas Keeper’s Residence HSR 

disconnected PVC downspout remaining on 

the residence. 

Recommendation: It is recommended that Kstyle gutters with round downspouts be 

installed on the residence. Sizing of these 

components will depend on rainfall analysis 

and required capacities. Despite reference to 

half-round gutters in some of the 

specifications, application of K-style gutters is 

consistent with early drawings and historic 

images of the residence. 

Exterior Walls 

The exterior walls have experienced moderate 

erosion of mortar and face brick due to 

weathering caused by the extreme conditions 

at the site. 

Evidence of past repointing campaigns 

conducted with incompatible mortars and of 

varying levels of workmanship indicates that 

erosion of the historic mortar has been 

occurring for some time. 

In addition, areas of the exterior walls along 

the tops of windows and between windows 

have experienced cracking of the mortar joints 

and brick caused by jacking of the steel lintels. 

This damage extends from the top corners of 

the windows horizontally around most of the 

perimeter of the building. The result is that the 

top eight to ten courses of brick at the top of 

the exterior walls has been shifted out of 

alignment. 

Where its removal will not result in damage to 

the brick, it is recommended that incompatible 

replacement mortars be removed, damaged 

brick replaced, and deteriorated joints 

repointed. 

The areas of past mortar replacement (as 

outlined in the Exterior Walls section of the 

Physical Description) are indicated by mortar 

that is darker grey in color, has a smoother 

consistency, and wider joints than the lighter 

gray, more textured, and narrower joints of 

the historic condition. 

Recommendation: Based on inspections 

made during the development of the HSR it is 

estimated that approximately 25% of the 

exterior walls should be repointed. 

Prior to repointing, the steel window and door 

lintels should be removed and replaced with 

316 grade stainless steel lintels. The new 

stainless steel lintels should be painted with a 

colored top coat to match the color of the 

historic lintels. 

Formulate repointing mortar to match as 

closely as is practicable, the composition of the 

original mortar. The mortar analysis identified 

ordinary gray Portland cement as the original 

binder with natural carbonate sand at a 

component ratio of 1:2.4. Given that modern 

Portland cements differ in character from 

their early-twentieth century counterparts it is 

recommended that the repair mix be tempered 

with lime. Consideration should also be given 

to using a Type II or Type V (sulfate resistant) 

Portland cement given the salt laden 

environment. Mock-ups should be prepared 

to ensure the most accurate match possible 

between the replacement and historic mortars. 

Brick to be replaced should also match 

existing brick in size, color, and texture. 

Front Porch Piers 

The brick, mortar joints and concrete caps at 

the front porch piers are cracked in multiple 

locations. These cracks appear to be the result 

of internal stresses caused by corrosion of iron 

components embedded within the piers. 

Although it could not be confirmed during the 

site inspection that metal components are 

present, historic documentation suggests that 

anchor rods were extended down through 

porch columns and into the piers as a means to 

secure the porch roof from uplift during 

hurricanes. 

Recommendation: It is recommended that 

the damaged piers be disassembled and the 

corroded anchors be removed and replaced if 

significantly deteriorated or blasted and 

coated with a protective finish. The damaged 

pier caps should be repaired through stone 

conservation measures by doweling the pieces 

together and securing with adhesive. 

Replacement brick should match existing 

brick in size, color, and texture and repointing 
Recommendations for Treatment 

National Park Service 101 

mortar should consist of Portland cement as 

the binder with natural carbonate sand at a 

component ratio of 1:3 (as recommended in 

the finish analysis.) 

Front and Rear Porch Flooring 

While the porch floors are generally sound 

structurally, there are individual boards that 

are damaged, including broken ends, split and 

cracking ends, and rot damage. The individual 

instances of this damage are outlined in the 

condition assessment above. In addition, the 

floor boards and structural members of the 

rear porch have been reoriented during a 

previous repair. 

Recommendation: It is recommended that 

damaged boards be repaired as possible and 

replaced as necessary. Treatment should 

include application of borate wood 

preservative to arrest any active rotting, 

followed by application of epoxy 

consolidation of affected wood and epoxy 

putty filler of missing wood. If use of epoxy 

products is not warranted, replace damaged 

portion of floor boards with in-kind materials. 

Install ledger board at rear porch or reorient 

floor structure to replicate original 

construction. In lieu of reorienting the 

flooring and structure, installation of the 

missing ledger board would conceal the 

original joist pockets and make the rear porch 

appear largely as it had originally. It is also 

recommended that the lattice screening that 

originally enclosed the rear porch be 

fabricated and reinstalled. 

Front Porch Railing 

The turned balusters of the porch railing were 

installed in the relatively recent past and are 

not in keeping with the character of the 

Craftsman influenced architecture. It is 

recommended that the porch railing be 

restored to its original appearance with 

closely-spaced square balusters as shown in 

historic photographs. 

Front Porch Stairs 

There is separation between the concrete 

stairs and brick cheek walls at the front porch 

stairs. It is recommended that this gap be 

pointed to prevent moisture infiltration. 

Front and Rear Porch Ceiling, 

Eave, Cornice, and Flooring 

The painted finish on the wood elements of 

the porches is at the end of its life span. With 

multiple layers of paint, the outer layers are 

chipping and flaking, particularly along the 

eave, cornice, and wood columns. 

These painted finishes likely contain lead and 

therefore consideration should be given to 

their removal. Alternatively however, it is 

recommended that the historic finishes be 

preserved in place and that the porch ceiling, 

eave and floors be repainted. 

Doors 

As described above in the “Exterior Wall” 

section, remove existing deteriorating steel 

lintels above door openings prior to 

repointing. Following replacement of the 

lintels, it is recommended that the existing 

non-historic exterior doors be replaced with 

new doors replicating the appearance of the 

historic entrance doors and surrounds. 

At the primary front door opening, restore the 

single wood door with flanking sidelights as 

indicated in historic images. At the side and 

rear door openings, restore the historic single 

wood doors as shown in historic images and 

drawings. 

Windows 

The existing windows installed in 2004 are in 

good condition and generally match the site 

lines of the historic units. However, it is 

recommended that the existing deteriorating 

steel lintels above all window openings be 

removed and replaced with new 316 grade 

stainless steel lintels as described above in the 

“Exterior Wall” section. 

In addition, it is recommended that damage to 

the concrete window sills and surrounding 

brick caused by the hurricane shutter guide 

tracks be repaired or the sills be replaced as 

necessary. Given that it will be necessary to 
102 Dry Tortugas Keeper’s Residence HSR 

remove and remount the existing hurricane 

shutter tracks in a secure fashion that 

minimizes damage to the historic fabric, the 

new hurricane shutters should be designed in 

a manner that will accommodate the 

installation of the historic louvered wood 

shutters. In the event of a hurricane, the wood 

shutters would be closed and the steel 

hurricane shutters would be installed over the 

wood shutters. The design of the louvered 

wood shutters should match those shown in 

historic images. 

Floor Plan 

Given that the building will continue to be 

used for residential purposes as has been 

initially indicated by Park staff, the existing 

floor plan can be retained as evidence of the 

evolution of changes to the building’s layout. 

Should the decision be made in the future that 

the structure is to be used to interpret the lives 

of Dry Tortugas Lighthouse keepers, 

restoration of the historic floor plan should be 

considered. 

Interior Floors 

Given its relatively good condition, it is 

recommended that the existing vinyl floor tile 

be maintained in place. It is less practical 

however to maintain the existing carpeting 

and therefore it is recommended that the 

carpeting be removed and the historic wood 

flooring be restored in these spaces. 

Given the possibility that the vinyl floor tile 

and/or mastic could contain asbestos, these 

materials should be tested as part of a 

regulated materials test. (See “Regulated 

Materials” section below). If the test results 

are positive, the tile can remain in place until it 

is damaged or becomes friable at which time it 

should be removed and the historic wood 

floors restored. 

Interior Walls 

It is recommended that the existing upper 

sections of the plaster walls and wood crown 

molding be retained and repaired as necessary. 

If the existing gypsum board wall finish is 

damaged or deteriorates to the point of 

replacement, it would be appropriate to 

remove the drywall to expose the historic 

plaster wall finish. 

Interior Ceilings 

If the existing gypsum board ceiling finish is 

damaged or deteriorates to the point of 

replacement, it would be appropriate to 

remove the drywall, and expose and repair the 

historic wood ceilings. 

Interior Moldings 

It is recommended that the existing historic 

crown molding present above the non-historic 

gypsum board walls be retained and repaired 

as necessary. In addition, the historic casings 

at the interior door and window jambs and 

heads should be retained. 

Interior Plaster Wall Conditions 

Hairline plaster cracks identified in the 

remaining top portion of the historic plaster 

walls above the gypsum board wall sections 

should be repaired with a gypsum-based 

patching material compatible with the historic 

finish. The locations of plaster damage are 

summarized below: 

• Living/Berthing Room (KR101) 

• Bedroom (KR103) 

• Bathroom (KR106) 

• Kitchen/Dining Room (KR107) 

Interior Gypsum Board 

Conditions 

Patch holes in the gypsum board wall and 

ceiling finishes. The locations of gypsum 

board damage are summarized below: 

• Laundry Room (KR105) 

• Bathroom (KR106) 

Interior Paint Conditions 

Deteriorated paint finishes identified on the 

interior surfaces should be scraped and 

repainted using a feather-edge technique and 

light sanding to reduce the paint thickness at 
Recommendations for Treatment 

National Park Service 103 

the edges. The rooms where this repair will be 

necessary are summarized below: 

• Hallway (KR102) 

• Bedroom (KR103) 

• Bathroom (KR106) 

• Kitchen/Dining Room (KR107) 

Electrical System 

The electrical system is in sound operating 

condition. When the electrical system is 

updated or replaced in the future, it would be 

appropriate to reuse existing conduit where 

possible to minimize damage to existing 

historic finishes. Replace faulty receptacles 

and switches as needed and minimize 

installation of additional receptacles and 

devices which typically have a negative impact 

on a building’s historic character. If the 

Keeper’s Residence will be continue to be 

used for residential purposes and not be open 

to the public, the existing non-historic 

fluorescent light fixtures can be maintained 

and reused where possible. 

It is also recommended that users of the 

Station’s housing facilities be better educated 

about the limits of the electrical system and 

energy saving measures that will help mediate 

demand during peak usage periods and reduce 

strain on the system. 

Propane Gas System 

The propane gas system is in sound operating 

condition. Ongoing maintenance and periodic 

replacement of propane tanks is 

recommended. It is also recommended that 

the propane tanks be relocated from in front 

of the crawlspace access to facilitate regular 

inspections of the foundation and floor 

framing systems. The existing shed roof can be 

reused and roofing shingles repaired or 

replaced to provide protection to the gas 

tanks. 

HVAC System 

The HVAC system is in sound operating 

condition and it is recommended that the 

existing system be maintained to provide 

necessary climate control for the residence. 

Plumbing System 

The plumbing system is in sound operating 

condition. In addition to ongoing maintenance 

of the plumbing system, it is recommended 

that the passive water heater be moved closer 

to the residence in order to reduce the amount 

of water wasted while waiting for heated water 

to reach the fixtures. 

Fire Suppression System 

Installation of a fire suppression system in the 

Keeper’s residence may not be practical based 

on the effects of the salt-laden environment 

would have on system components and the 

lack of available fresh water. It is 

recommended that protection of the building 

and occupants be provided through a smoke 

detection system and accessible extinguishers. 

Accessibility 

Providing increased public access to 

Loggerhead Key carries with it several 

limitations and challenges. Assuming that 

transportation to the Key is resolved, visitors 

to Loggerhead would likely disembark onto 

the main dock on the east shore of the island 

and then walk a short distance on concrete 

walkways to the Light Station. The incline 

from the dock to the Light Station is gradual 

but in certain areas exceeds permissible slope 

limits for wheelchair use. In addition, windblown sand often covers the surface of the 

concrete walks. Given this difficulty of 

providing barrier-free access to Loggerhead 

Key and the Light Station buildings, providing 

full access to the interior of the Keeper’s 

Residence may not be a practicable 

expectation. 

In the event an accessible route to the building 

is established it would be necessary to 

construct a ramp to provide access to the first 

floor. Given the first floor’s height above 

grade, the ramp would have a substantial 

footprint and therefore a significant visual 

impact on the character of the building. 

Regulated Materials 

Based on the likely presence of asbestos in the 

vinyl asbestos floor tile and lead in the paint, it 
104 Dry Tortugas Keeper’s Residence HSR 

is recommended that an environmental survey 

of the building be conducted to define the 

content, location and quantity of identified 

hazardous materials. 
National Park Service 105 

Sources of Information 

Bearss, Edwin C. Historic Structure Report, Historical 

Data Section, Fort Jefferson: 1846-1898 Fort 

Jefferson National Monument. 1983.

______. Shipwreck Study-The Dry Tortugas. 

Washington, DC: Eastern Service CenterOffice of History and Architecture, 

Department of the Interior, National Park 

Service, 1971. 

Calder, Dale R. and Lester D. Stephens. Seafaring 

Scientist: Alfred Goldsborough Mayor, Pioneer 

in Marine Biology, Columbia, South Carolina: 

University of South Carolina Press, 2006. 

Cipra, David L. Lighthouses, Lightships, and the Gulf of 

Mexico. Alexandria, Virginia: Cypress 

Communications, 1997. 

Dean, Love. Lighthouses of the Florida Keys. Sarasota, 

Florida: Pineapple Press, 1998. 

Ebert, James D. “Carnegie Institution of Washington 

and Marine Biology: Naples, Woods Hole, 

and Tortugas.” Washington, DC: Carnegie 

Institute of Washington, 1985. 

Florida Center for Instructional Technology, College 

of Education. “Florida’s Role in the Civil 

War: ‘Supplier of the Confederacy’.” 

University of South Florida. 

 http://fcit.usf.edu/Florida/cvl_war1.

htm. 

Holland, Jr., Francis R. America’s Lighthouses: Their 

Illustrated History Since 1776. Brattleboro, 

Vermont: Stephen Greene Press, 1972. 

Hurley, Neil E. Lighthouses of the Dry Tortugas, An 

Illustrated History. Aiea, Hawaii: Historic 

Lighthouse Publishers, 1998. 

Johnson, Stuart and Richard Ramsden. Rehabilitation 

Report and National Register Nomination for 

the United States Coast Guard Light Station 

Dry Tortugas Light Station, Loggerhead Key, 

Florida. National Park Service, 1984. 

Manucy, Albert. A Constructional History of Fort 

Jefferson 1846-1874. Atlanta, Georgia: 

National Park Service Southeast Region, 

1961. 

Organization and Duties of the Light-House Board and 

Regulations, Instructions, Circulars, and 

General Orders of the Light-House 

Establishment of the United States, 

Washington, DC: Government Printing 

Office, 1871. 

Tag, Thomas. “The Early Development of the Fresnel 

Lens.” U.S. Lighthouse Socieity, The Keeper’s 

Log, Summer, 2005. www.uslhs.org. 

______. “The Sautter Lens Works Producers of the 

Fresnel Lens—Parts 1 and 2” U.S. 

Lighthouse Society, The Keeper’s Log,

Summer, 2005. www.uslhs.org. 

U.S. Congress. Light-house and Appropriation Bill. 

Lighthouse Board. 32nd Congress, 1st sess., 

Statues at Large of the United States of 

America, 1789-1873. vol. 10, August, 1852. 

______. Light-house and Appropriation Bill. 34th

Congress, 1st sess., Statues at Large of the 

United States of America, 1789-1873. vol. 11, 

August, 1856. 

U.S. Lighthouse Board. Registers of Lighthouse 

Keepers, 1845-1912. National Archives and 

Records Administration Southeast Region, 

Morrow, Georgia. 

______.List of General Correspondence, 1791-1900. 

National Archives and Records 

Administration, Washington, DC. Record 

Group 26. NC-31. Series 38. 

United States Coast Guard. Records Concerning 

Illuminating Apparatus, 1839-1960. National 

Archives and Records Administration, 

Washington, DC. Record Group 26. NC-31. 

Entry 59. 
106 Dry Tortugas Keeper’s Residence HSR 

______. Logbook of Lightstations. National Archives 

and Records Administration, Washington, 

DC. Record Group 26. NC-31. Entries 5, A1 

330E, A1 330M, A1 330T, A1 330S, A1 330Z, 

A1 330AF,159D-159I. 

______. Studies and Surveys. National Archives and 

Records Administration, Washington, DC. 

Record Group 26. NC-31. Entry A1 345. 

______. Boards of Survey (Real Property) Case Files. 

National Archives and Records 

Administration, Washington, DC. Record 

Group 26. NC-31. Entries A1 99 and 99a. 

______. Light Station Files. National Archives and 

Records Administration, Washington, DC. 

Record Group 26. NC-31. Entry 381. 

United States Department of Commerce. 

Recommendations as Aids to Navigation. 

National Archives and Records 

Administration, Washington, DC, Record 

Group 26 (These forms are filed within NC31. Entry 51. Boxes 408 and NC-31. Entries 

A1 99 and 99a and occasionally among other 

records. They are standard appropriation 

request forms.) 

United States Lighthouse Board. Dry Tortugas 

Clipping File. National Archives and 

Records Administration, Washington, DC. 

Record Group 26. NC-63. Entry 13. 

United States Bureau of Lighthouses. National 

Archives and Records Administration, 

Washington, DC. Record Group 

26. NC-31. Entry 51. Boxes 408 and 862. 
APPENDIX A 

Draft National Register Nomination 























APPENDIX B 

Materials Analysis 

Dry Tortugas Light Station

Materials Analysis

Dry Tortugas, Florida

Prepared For

Lord Aeck & Sargent Architecture

Ann Arbor, Michigan

Prepared By

Building Conservation Associates, Inc.

329 Race Street

Philadelphia, Pennsylvania 19106

CONTENTS

1.0 INTRODUCTION .........................................................................................1

2.0 METHODOLOGY...........................................................................................5

2.1 Finishes Analysis .................................................................................5

2.2 Mortar and Plaster Analysis ............................................................8

3.0 SUMMARY OF FINDINGS............................................................................9

3.1 Finishes Analysis ................................................................................9

3.2 Mortar and Plaster Analysis.............................................................18

4.0 CONCLUSIONS & RECOMMENDATIONS ...........................................23

4.1 Finishes ................................................................................................23

4.2 Mortar...................................................................................................31

APPENDICES

Appendix A: Sample Stratigraphies and Photomicrographs

Appendix B: Mortar and Plaster Analysis Report (Testwell, Inc. 2009)

Appendix C: Rehabilitation Report and National Register Nomination for the United Stated Coast 

Guard Light Station, Dry Tortugas Lighthouse, Loggerhead Key, Florida, 1984

DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 1

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

1.0 INTRODUCTION

At the request of Rob Yallop of Lord Aeck & Sargent Architecture (LAS), Building Conservation 

Associates, Inc. (BCA) prepared an analysis of select building materials removed from buildings 

associated with the Dry Tortugas Light Station, including the Dry Tortugas lighthouse. The light 

station is located in the Dry Tortugas National Park in Florida. The materials investigated as part of 

this study include mortar and paint finishes. The buildings investigated as part of this study include:

the lighthouse, original oil house, kitchen building, keeper’s residence and the south brick cistern. The 

primary goal of the materials analysis is to document the buildings’ original mortars and paint finishes 

for inclusion in a Historic Structure Report (HSR). A secondary goal is to provide recommendations 

for future restoration work based on the findings of the analysis. (Figures 1-5)

The report summarizes the findings of both the mortar analysis and the finishes study. Following the 

introductory information regarding the site and study methodology, the report discusses the findings 

of the research and then makes recommendations for appropriate restoration mortar mixes and 

paint colors. All mounted cross-sections have been labeled and permanently housed and will be 

archived at BCA’s Philadelphia office unless otherwise requested by the client.

All work required for the execution of this study was performed by Dorothy S. Krotzer, BCA 

Regional Director, with assistance from Testwell, Inc. for completion of the laboratory portion of the 

mortar analysis. Mortar and paint samples were taken from the site in March 2009 and laboratory 

analysis was performed in April and May 2009. 
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 2

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

.

Figure 2. Oil house, March 

2009. Photograph by author.

Figure 1. Lighthouse, 

March 2009. Photograph by 

author.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 3

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

Figure 3. Original kitchen building. March 2009. Photograph by author.

Figure 4. Keeper’s residence. March 2009. Photograph by author.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 4

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

Figure 5. South brick cistern. March 2009. Photograph by author.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 5

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

2.0 METHODOLOGY

Prior to the site visit and removal of samples, information related to the history of the Dry Tortugas 

Light Station provided by LAS was reviewed. Portions of the draft HSR, including historic images and 

information on the construction chronology and materials, were studied in order to gain a general 

understanding of the history of the site and any information related to the buildings’ paint finishes and 

masonry construction. The archival information included a 1984 Rehabilitation Report and National 

Register Nomination that contained paint and mortar analysis of the lighthouse. (Appendix C)

Once the relevant historical documentation was reviewed, a site visit was made and the buildings 

were physically examined for areas from which representative samples of mortar and paint finishes 

could be removed. Once these intact areas were identified, samples were removed. Mortar and 

plaster samples were removed using a small masonry chisel or five-in-one tool and a hammer. Paint 

samples were removed using a scalpel. A total of eleven mortar and plaster samples and sixteen finish 

samples were removed from the buildings and taken back to the laboratory for analysis. 

2.1 Finishes Analysis

All finish samples were initially examined in reflected light using a Nikon high-resolution 

stereomicroscope SMZ-1500 with variable magnification (16x-160x) to identify which samples would 

be embedded and sectioned for analysis. The selected samples were then mounted in a commercial 

polyester/methacrylate resin polymerized with a methyl ethyl ketone peroxide catalyst (Bioplast®). 

Embedded samples were sectioned on a Leco® VC-50 micro-saw for microscopic examination. The 

sectioned samples were dry-polished using a series of fine Micromesh® polishing cloths ranging from 

6,000 to 12,000 grit. Sectioned samples were observed under a Nikon 50i compound microscope in 

both visible light filtered through a daylight correction filter and ultraviolet light. The ultraviolet light 

was generated by a mercury illumination system filtered through a violet filter cube (EF4 V-2A 

Ex400/40 Dm430 Bar 450). Photomicrographs of representative samples were taken using a five 

megapixel Nikon DigiSight color digital camera system and are included in this report to illustrate 

specific observations.

All paint samples were viewed in cross-section and their paint layering sequences, or stratigraphies, 

recorded. These stratigraphies are included in Appendix A. Once the stratigraphies of every sample 

were deciphered, significant paint layers were identified and raw samples were manipulated in order 

to expose these layers for color matching purposes. Once the target layers were exposed, they were 

subjected to a bleaching process in order to reverse any yellowing that may have occurred over time. 

It is well documented that linseed oil-based paints (especially pale-colored paints) darken and yellow 

over time if not exposed to sunlight. This even affects oil-based finishes that have been covered with 
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 6

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

subsequent paint layers. In order to diminish this yellowing of paint layers, they were exposed to an 

ultraviolet light source for approximately two weeks.

Following the bleaching process, the exposed layers were subjected to a portable 

spectrophotometer, a GretagMacbeth X-Rite EyeOne®., in order to generate a CIE L*a*b* value for 

each sample. Then, each sample was visually matched to two different color systems, the 

standardized Munsell color system and the commercial Benjamin Moore paint palette. The 

spectrophotometer was then used to generate CIE L*a*b* values for each of the color matches. 

A color in the CIE L*a*b* system is defined according to three axes. The L*-axis (from 0 to 100)

is the light-dark axis. The a*-axis (from –100 to +100) is the green-red color axis. The b*-axis

(from –100 to +100) is the yellow-blue axis. Delta E is a measurement of the color difference

between the original paint surface color and the closest color matches that BCA has

identified. A perfect match would have a Delta E value of 0.00. Delta E equals the square root of

[(L*1 – L*2)2 + (a*1 – a*2)2 + (b*1 – b*2)2]. Where L*1, a*1, b*1 are the original paint surface values

and L*2, a*2, b*2 are the commercial paint values. Consequently, the lower the value of Delta E,

the closer the match. Although several commercial colors were tested for each element, only the 

closest match has been presented. All color matches are included in Section 4.1 of this report.

Finish samples were removed from the following locations:

LOKE.F.1 Oil house Exterior, east wall (now enclosed), finishes on 

brick.

LOKE.F.2 Passageway between oil 

house & lighthouse

Interior, south wall, finishes on concrete. For 

comparison with LOKE.F.1.

LOKE.F.3 Oil house Exterior, east wall (exposed), finishes on brick.

LOKE.F.4 Oil house Exterior, east wall (now enclosed), door frame, 

finishes on wood.

LOKE.F.5 South brick cistern Exterior, west wall, finishes on brick.

LOKE.F.6 Lighthouse Exterior, west elevation (now enclosed), 

finishes on brick. 

LOKE.F.7 Lighthouse Exterior, west wall (now enclosed), door 

frame, finishes on wood.

LOKE.F.8 Lighthouse Exterior, west wall (now enclosed), door to 

lighthouse, finishes on wood.

LOKE.F.9 Lighthouse Interior, ground floor level, finishes on brick.

LOKE.F.10 Kitchen building Exterior, east elevation, finishes on brick.

LOKE.F.11 Oil house Exterior, south elevation (now enclosed), 

finishes on brick.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 7

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

LOKE.F.12 Keeper’s residence Interior, hallway outside bathroom, original 

west wall (covered by drop ceiling), finishes on 

plaster.

LOKE.F.13 Keeper’s residence Interior, hallway outside bathroom, original 

west wall (covered by drop ceiling), original 

wood cornice, finishes on wood.

LOKE.F.14 Keeper’s residence Interior, bathroom, original west wall, finishes 

on plaster.

LOKE.F.15 Keeper’s residence Exterior, east elevation, front door frame, 

finishes on wood.

LOKE.F.16 Keeper’s residence Exterior, east elevation, front porch beam 

above columns, back face, finishes on wood.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 8

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

2.2 Mortar and Plaster Analysis

Cursory visual examination of the mortar samples was performed by D. Krotzer and subsequent 

laboratory analysis was executed by John Walsh of Testwell Laboratories, Inc. in Ossining, New 

York. John Walsh specializes in the analysis and identification of historic mortar materials. Testwell’s 

laboratory work included: petrographic examination; chemical analysis (gravimetric analysis and 

atomic absorption spectroscopy); statistical point counting (used instead of acid digestion to gain 

information on the quantity of aggregate since it is an acid-soluble carbonate sand); and water-soluble 

chloride analysis. The goal of Testwell’s analysis was to identify the binder and aggregate components 

of each mortar, as well as the original component ratio and any deterioration due to salt 

crystallization or hydration.

Although Testwell’s findings are discussed in Section 3.2 of this report, the full mortar analysis report 

has also been included in Appendix B.

Samples of brick mortar and plaster were removed from the following locations:

LOKE.M.1 Oil house Exterior, east elevation, mortar. Taken from 

protected wall now enclosed. Sample from 

interior of wall (from an area where a hole was 

cut through wall for a pipe).

LOKE.M.2 South brick cistern Exterior, east elevation, mortar.

LOKE.M.3 South brick cistern Interior, parging. Taken from upper portion of 

interior wall.

LOKE.M.4 Lighthouse Exterior, west elevation, mortar. Taken 

approx. 8-feet from ground.

LOKE.M.5 Lighthouse Exterior, west elevation, mortar. Taken from 

former exterior wall now enclosed, adjacent 

to entrance to lighthouse.

LOKE.M.6 Lighthouse Interior, mortar. Taken from wall at ground 

floor level.

LOKE.M.7 Lighthouse Interior, mortar. Taken from wall below watch 

level (supposedly rebuilt in 19th century).

LOKE.M.8 Oil house Interior, south wall, plaster. Taken from behind 

modern wood paneling and earlier beadboard 

wall; three-layer plaster system applied over 

brick.

LOKE.M.9 Kitchen building Exterior, north elevation, mortar. Sample from 

interior of wall.

LOKE.M.10 Keeper’s residence Exterior, west wall, mortar.

LOKE.M.11 Keeper’s residence Interior, bathroom, west wall, plaster. Twocoat plaster system.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 9

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

3.0 SUMMARY OF FINDINGS

3.1 Finishes Analysis

The paint finishes of five historic buildings at the Dry Tortugas Light Station were examined as part of 

this study. The majority of paint samples were removed from exterior brick and wood trim 

elements. However, samples of interior paint were also removed from the keeper’s residence and 

the lighthouse.

MASONRY

The exterior brick masonry surfaces of the oil house, south brick cistern and lower half of the 

lighthouse all seem to share a similar finish history. Each of these buildings has been painted a version 

of cream or white throughout its history, although the total number of layers varies. In addition, the 

earliest finish appears to be a white lime wash, followed by paint finishes (presumably oil-based) that 

are also white/cream in color. The brick masonry of the kitchen building was examined and found to 

only have four layers of modern white paint. The upper portion of the lighthouse (currently painted 

black) was not accessible at the time of the field investigation.

Although the brick masonry of the oil house, kitchen building, lighthouse and south brick cistern is 

currently painted, historic documentation indicates that originally the brick on these buildings was left 

unpainted. An undated historic photograph shows both the kitchen building and the oil house as 

exposed brick structures. (Figure 6) Although the date of this photograph is unknown, it must predate 1892 because a photograph taken circa 1892 clearly shows the oil house painted. (Figure 7) In 

the same circa 1892 photograph, the brickwork of the kitchen building, barely visible through the 

palm trees, remains unpainted. In addition, there are several written descriptions of the lighthouse 

dating from 1858 that refer to it as being a “natural color brick” or as a “brick-color tower.”1

Physical evidence confirms the historical documentation. The surface of the brick in samples 

removed from these buildings appears somewhat weathered and uneven, suggesting it was worn by 

exposure to the elements before being painted. The only structure that may have always been 

painted was the south brick cistern. As evidenced in Figure 9 the sample removed from the 

brickwork of the cistern shows a relatively clean brick surface, suggesting it has always been 

protected from the weather. (Figures 8-9)

 1 “Loggerhead Key Lighthouse, Dry Tortugas, Florida.” Printed October 21, 1993. PP. 1-2
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 10

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

Figure 6. Historic image showing the oil house and kitchen building as unpainted brick masonry buildings. 

The Lighthouse has been painted black and white but the oil house is not yet painted, dating this photograph 

to some time between 1870 and 1892.

Figure 7. Historic image showing the 

lighthouse, oil house and old keeper’s 

residence circa 1892. Note that the oil 

house has been painted white in this 

photograph. Photograph courtesy of LAS.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 11

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

Figure 8. Oil house. Photomicrograph of painted exterior brick showing 

numerous layers of cream and white-colored paint. (40x magnification, visible 

light).

Figure 9. South brick cistern. Photomicrograph of earliest finish applied to brick 

wall of cistern. Note first layer is more translucent than the others and appears to 

be a limewash. Also, the surface of the brick is relatively unsoiled. (100x 

magnification, visible light).
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 12

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

Although archival documentation indicates that the lighthouse was not originally painted, records 

document that it has been painted black and white at least since 1875, when an inspection log states

that “The black portion of the tower has been painted, and the remainder whitewashed.”2

Interestingly, this reference illustrates the use of two different types of paint finishes on the brick 

structures of the Dry Tortugas Light Station, a practice that may have been applied to not only the 

lighthouse but to the other buildings as well. For the lighthouse, it would have been necessary for the 

black finish to be a paint (presumably oil) instead of a lime wash, as achieving a truly black-colored 

lime wash would have been difficult if not impossible. 

A Rehabilitation Report and National Register Nomination on the Dry Tortugas lighthouse from 1984 

included materials analysis of the paint by Law Engineering Testing Company. One paint sample from 

the lighthouse was provided for analysis. Although the location of the sample was not indicated, it is 

assumed that the sample was removed from the exterior of the lighthouse. According to the 1984 

report, the paint sample consisted of two paint layers, both found to be an acrylic-polyvinyl acetate 

mixture with lead and zinc-based pigments. A recent in situ examination of the lighthouse exterior 

for this report confirms the presence of only a few layers of modern white paint on the exposed 

portion of the lighthouse exterior. This number of paint layers is far fewer than the approximately 30 

paint layers documented for the paint sample removed from a protected area of the lighthouse 

exterior (from a wall inside the connector building) as part of the current study. This discrepancy in 

number of paint layers can most likely be attributed to the fact that the exterior of the lighthouse 

was sandblasted in 1967. The blasting would have removed any early coatings, explaining why the 

sample examined in 1984 had only two paint layers and why the recent in situ investigation revealed 

only a few paint layers on the exposed portion of the lighthouse exterior. The paint sample removed 

from the protected area inside the connector is more representative of the complete finish history of 

the lighthouse exterior and provides insight into the building’s earliest finishes.

WOODWORK & METALWORK

The exterior woodwork of the four buildings (oil house, lighthouse, kitchen building and keeper’s 

residence) was also examined. The exterior door and doorframe of the lighthouse, currently 

enclosed by the link to the original oil house, contain between 30-35 layers of paint. The doorframe 

contains more paint layers than the door, suggesting it may pre-date the door. The earliest paint 

layers on the frame are cream-colored paint. After these, the frame was painted various shades of 

grays approximately 30 times. The door contains slightly fewer layers (approximately 30), all of which 

are various shades of gray. The doorframe of the original oil house was also painted numerous times 

(approximately 40 paint layers). The earliest finish is a medium gray. Subsequent layers are 

predominantly gray with a few creams later in the sequence. The wood trim of the kitchen building 

 2 LAS, Draft Historic Structure Report (HSR), “Background” section.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 13

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

contains only a few layers of modern paint, indicating the woodwork is relatively modern or that it 

has been stripped. (Figures 10-11)

The historic photographs provide some insight into the color palette of the exterior woodwork of 

these buildings. In both photographs, the window sash and frames of all of the buildings appear to be 

a pale color (likely white or cream) and the shutters are a dark color. However, at the time of this 

study, there was no access to historic windows in these buildings, as many have been replaced with 

modern units and the shutters have been removed. This prevented a positive identification of the 

actual color of the pale paint visible in the photographs. 

In the historic images shown in Figures 6 and 7, the doors of the buildings are typically open in the 

photographs, preventing the color of the doors from being seen; they could have been painted the 

light color of the windows or the dark color of the shutters. As discussed above, the physical 

evidence indicates that the door frame (and possibly the door) of the lighthouse was originally 

painted white, followed by numerous layers of gray paint. It is not know when the transition from 

white to gray occurred for the lighthouse. By contrast, the door frame of the original oil house was 

always painted gray. Again, there is no photographic evidence to corroborate either of these 

observations.

There is, however, written historic documentation regarding paint for the metalwork and woodwork 

of the lighthouse. In an 1862 document entitled “Instructions and Directions for Light-House and 

Light-Vessel Keepers of the United States”, paint colors and paint types are carefully specified for the 

interior and exterior metal and wood work of the lighthouse. All paint is linseed-oil based and 

generally glossy in sheen. The interior of the lighthouse lantern is to be painted white, while the 

exterior is to be painted black or red. Black seems to be the most prevalent color called for, 

although there are also references to “lead”, “gray”, “yellow”, “straw”, “brick”, “oak wood” and 

“Portland stone.” In addition, all ironwork is supposed to be primed with red lead.3 Although the 

metal components of the lighthouse were not examined as part of this study, the colors found on the 

existing woodwork (white and gray) are in keeping with the colors specified in 1862.

The exterior woodwork of the keeper’s residence was originally painted white, a conclusion based 

on both physical and archival documentation. Samples removed from the front porch trim show 11 

layers of white and cream paint. In addition, historic photographs of the house show white-colored 

trim and the preliminary specifications for the building that date to 1917 state that all woodwork was 

to be painted white. (Figure 12) The original hurricane blinds, which appear a dark color in the 

historic photographs, do not remain on the building and could therefore not be sampled to confirm 

 3

 Instructions and Directions for Light-House and Light-Vessel Keepers of the United States, 4th edition, 1862. 

Pages 106-110.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 14

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

Figure 10. Oil house. Photomicrograph of a paint sample removed from the exterior 

door of the oil house showing numerous layers of gray paint applied to the frame over 

time. (100x magnification, visible light).

Figure 11. Lighthouse. Photomicrograph of a paint sample removed from the 

exterior door frame of the lighthouse showing a similar range of gray paint colors as 

the sample above, although the earliest paint color was cream. (40x magnification, 

visible light).
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 15

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

their original color. However, the preliminary specifications state that they are to be painted green. 

(Figure 13)

Select interior finishes of the keeper’s residence were also examined. Samples were removed from 

the plaster walls of the hallway and bathroom and the wood cornice of the hallway. The walls of both 

the hall and bathroom were painted a pale gray-green originally and the cornice was painted white, 

after having been sealed with a clear coat. The preliminary specifications call for the wood to be 

sealed with shellac and for a three-coat paint system (1 primer and 2 finish coats), all white in color. 

While the sealer layer and three-coat system seems to have been employed, the color varied from 

that included in the specification. (Figure 14)
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 16

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

Figure 12. Historic image showing the exterior of the keeper’s residence. Note light-colored trim on most 

exterior woodwork with the exception of the hurricane blinds.

Figure 13. Keeper’s residence. Photomicrograph of a paint sample removed from the exterior 

porch trim contains only cream and white-colored paint. (100x magnification, visible light).
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 17

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

Figure 14. Keeper’s residence. Photomicrograph of a sample of paint removed from 

the plaster wall’s of the bathroom. Note original three-layer paint system of two 

primers topped by a pale gray-green. (100x magnification, visible light).
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 18

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

3.2 Mortar & Plaster Analysis

MORTAR

Laboratory analysis indicates that the majority of mortars used historically at the Dry Tortugas Light 

Station are composed of natural cement and local carbonate sand. Lime, which would have been 

added to the mortars as a gauging material to improve workability, was not documented in any of the 

historic mortars analyzed as part of this study. The natural cement and sand mortars were found at 

the lighthouse, the oil house, the original kitchen building and the south brick cistern. In addition, 

samples of mortar removed from four different locations within the lighthouse, including the portion 

of brick masonry directly below the watch room floor plate, were as natural cement and carbonate 

sand mortars that ware virtually indistinguishable from one another. The similarity of these mortars 

makes it difficult to draw any conclusions about the date of installation or type of mortars used for 

the numerous repair campaigns made to the lighthouse, which were documented in extensive 

written material. However, the physical evidence suggests that, although there were numerous 

repairs campaigns, the same mortar mix and ingredients were used consistently for the majority of 

the re-pointing campaigns in the 19th century. (Figure 15)

The natural cements in these mortars were identified as American natural cements, typical of those 

manufactured in Rosendale, New York or Louisville, Kentucky. The sand in all mortar samples was 

identified as a natural carbonate sand containing coral and shell fragments, presumably the same sand 

found along the shore of Loggerhead Key. The sand is fairly narrowly-graded, with the bulk of the 

material falling between a No. 16 and a No. 30 sieve. Given the remote location of the key, use of 

materials at hand such as beach sand for the construction of these buildings would have been 

practical as well as commonplace.

Establishing original component proportions for these mortars was challenging due to the acidsoluble carbonate sand. Instead of dissolving the binder through chemical means and extracting the 

insoluble sand, a different approach involving microscopical point-counting of sand and binder 

components and bulk chemical analysis of representative mortar samples had to be preformed. Using 

this non-traditional two-tiered approach revealed that the original binder to aggregate ratio of the 

Dry Tortugas Light Station mortar samples is approximately 1 part natural cement to 1.5 parts sand, 

by volume. This is a fairly typical mix for historic natural cement mortars. A more in-depth discussion 

of the methodology used to determine this ratio is discussed in Appendix B.

A natural cement is defined as an eminently hydraulic lime that is typically derived from the burning

of highly impure limestone. It is these impurities that give the lime the characteristic of hydraulicity, 

or the ability to set by reaction with water (no air is needed, unlike with pure high calcium limes). 

Natural cements differ from Portland cements, which were produced later, in that the latter are 

artificially produced. Portland cements of the 19th century were made by grinding together chalk and 
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 19

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

clay and then heating the mixture at high temperatures to produce a simulated natural cement. Both 

natural and Portland cements can have quite high strength and durability. Natural cement based 

mortars were quite common in the mid to late 19th century and would have been readily available 

when these buildings were constructed. 4

The use of natural cement and carbonate sand mortars is, of course, not surprising given what we 

know about the construction of nearby Fort Jefferson, which dates to roughly the same period and is 

associated with the same builders. In fact, Captain H.G. Wright, who oversaw the construction of 

Fort Jefferson, wrote a proposal to the Light House Board for the construction of the Dry Tortugas 

lighthouse in which he calls specifically for the use of cement mortars with no lime. Writing in 1855, 

he states: “I am disposed to believe that the mortar for both brickwork and concrete should be 

made of cement and sand without any admixture of lime, and in the proportion of two parts of the 

latter to one of the former in powder.”5 Note that the ratio Wright calls for is quite close to that 

documented in the current lab analysis.

Although Wright does not specifically call for “natural cement”, there was no other commercially 

available cement in the United States until Portland cement was introduced in the 1870s. So, the 

mortar Wright was specifying was indeed meant to be a natural cement based mortar. There were 

many subsequent repair campaigns that involved re-pointing weathered brick joints as well as 

significant reconstruction of a portion of the masonry below the lighthouse lantern in 1875. Natural 

cement mortars were specified for some of the re-pointing repairs, namely those made to the 

lighthouse in 1868.

The Rehabilitation Report from 1984 also included chemical analysis of a mortar sample taken from the 

Dry Tortugas lighthouse. The results of this report conflict with the findings presented here. The 

report identified the mortar sample as a lime-based mortar with a small percentage of Portland 

cement and possibly gypsum as the binder mix, and fine silica sand and shell fragments as the 

aggregate. Because the aggregate contains calcium carbonate-based shell fragments, the acid in the 

chemical analysis will dissolve the aggregate as well as the binder, and will therefore not provide an 

accurate reflection of the mortar proportions. In addition, it also may cause the binder to be 

misidentified as lime. The author of the 1984 report does note that because of the shell content of 

the mortar, precise identification of the binder to aggregate ratio is impossible, but they still provide 

an approximate ratio of 1part cement, 3 parts lime and 12 parts sand.

 4

 Eckel, Edwin C. Cements, Limes and Plasters. Reprinted Third Edition. Dorset: Donhead Publishing, 2005. Page 

242.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 20

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

Figure 15. Lighthouse. Area of historic mortar removed for analysis. Note 

characteristic carbonate sand inclusions.

 5

 LAS, Draft Historic Structure Report (HSR), “Background” section. [Reference: Dry Tortugas Light Station 

clipping file, Appendix no. 17, H.G. Wright, Capitan of Engineers, Fort Jefferson, FL, letter to Lieutenant T.A. 

Jenkins, U.S.N., secretary, Light-house Board, Washington, D.C., September 23, 1855, Record Group 26, NA.]

Figure 16. Oil house. Area of early 

plaster, discovered behind later wall 

finishes, removed for analysis.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 21

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

The only mortar analyzed as part of this study that did not contain natural cement was the mortar 

removed from the exterior brickwork of the keeper’s residence, which dates from 1922-23. This 

mortar is composed exclusively of Portland cement and the same local carbonate sand; no lime was 

detected in this mortar either. The estimated cement to sand ratio, by volume, is 1 part cement to 

2.4 parts sand.

Archival research supports the use of Portland cement and local sand in the construction of the 

keeper’s residence. The 1920 specifications for the construction call for mortar to be composed of 

“1 part [Portland] cement and 2-1/2 parts sand. Hydrated lime not to exceed 10% by volume of the 

cement shall be used for tempering.”6 Although the mortar specifications were written for concrete 

block and not brick, the information can certainly be applied to the brick. In fact, the ingredients and 

proportions documented in the current lab analysis are almost identical to those included in the 1920 

specifications.

The mortars were also examined for the presence of any deterioration due to salt crystallization or 

salt hydration. This examination was performed petrographically, looking for signs of microcracking, 

and chemically, looking for elevated levels of water-soluble alkali salts (sodium, potassium and 

chloride). In general, most mortar samples exhibit “good microstructural integrity”, with no evidence 

of deterioration from salts. Although some minor sulfate deposits and chlorides were detected, they 

are not related to any significant cracking distress. In addition, the presence of alkali salts is most 

likely due to the original mortar mix and the use of unwashed sands, an not from subsequent 

deposits of salt from the environment.

PLASTER

Interior plaster of two of the historic buildings was also examined. In the oil house, a sample of a 

three-coat plaster system, discovered behind a layer of modern wood paneling and a bead board 

wall, was removed for analysis. The plaster is composed of: a lime and carbonate sand scratch coat 

gauged with natural cement, a natural cement and carbonate sand brown coat, and a lime-based finish 

coat that is gauged with gypsum (no sand). Although it is unclear when this plaster dates from, it is 

possible that it is original to the building and dates to the 1850s. The sand used in the scratch and 

brown coats is the same as that used in the brick mortar of the same building, a local carbonate sand.

(Figure 16)

The other interior plaster examined for this study was removed from the keeper’s residence, and 

presumably dates to the original 1922-23 period of construction. The plaster is a two-coat system, 

with gypsum and sand-based scratch coat and a gypsum-based finish coat gauged with lime. The 

brown coat is consistent with a Keene’s cement mixture. Keene’s cement is a slow-setting, hard-

 6

 1920 specification, page 3.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 22

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

finish plaster produced by burning very pure gypsum at high temperatures and treating the material 

with alum or other chemicals during the manufacturing process.7 The current lab findings indicate 

that a different plaster was used than what was originally specified. The preliminary specifications for 

the keeper’s residence, which date to 1920, call for the use of cement and lime plaster and not 

gypsum. However, the finish plaster was to be “cement plaster equal to the US Gypsums Co’s 

Adamant’”, a fire-resistant type of early drywall.

For a more in depth discussion of the specific findings of the mortar and plaster analysis performed 

as part of this study, including detailed characterization of the aggregate and binder as well as 

annotated photomicrographs, refer to Appendix B.

 7

 Edwin C. Eckel. Cements, Limes and Plasters: Their Materials, Manufacture and Properties. Michigan: Donhead 

Publishing Co. 2005 (originally published 1905), 78.
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 23

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

4.0 CONCLUSIONS AND RECOMMENDATIONS

4.1 Finishes

MASONRY

The recommendation for an appropriate paint finish for the masonry of the historic buildings at the 

Dry Tortugas Light Station is fairly straightforward. The white finish on the brick masonry portions of 

the lighthouse, oil house, south brick cistern and kitchen building should be maintained (note that the 

masonry portions of the keeper’s residence were never painted). Even though archival and physical 

evidence indicates that these buildings were not originally painted (possibly with the exception of the 

cistern), a white finish was applied early enough in their history that it can be considered historically 

significant. For instance, the oil house was painted white by circa 1892 and the lighthouse was painted 

with its current black and white scheme by 1875. In the case of the lighthouse, not only is the black 

and white paint scheme historic, but it also defines the lighthouse’s appearance and its identity. In 

addition to being historically appropriate, the use of a finish on the brick masonry of these buildings 

also affords a level of protection for the brick substrate by protecting it from wind and moisture that 

would no doubt take a toll on the surface of the brick over time, possibly eroding away the fire skin 

and making the brick even more susceptible to weathering. 

Although the brick of these buildings should be maintained white, the type of finish used to achieve 

this white color should be carefully considered. Archival evidence indicates that both limewash and 

oil paints were used historically on the buildings at the Dry Tortugas Light Station, although where 

each of these finishes was used is not always made clear. Physical evidence, however, suggests that 

white limewash was used on the brick portions of these buildings, with the exception of the black 

paint on the top half of the lighthouse, and oil paint was used on the wood elements. The use of 

limewash on masonry structures was commonplace throughout history and into the early 20th

century. It was an inexpensive and readily available finish. From a preservation perspective, limewash 

is a perfect finish for masonry substrates because it forms a good bond, it is moisture-permeable and 

it resists biological growth. It could also be renewed both easily and cheaply. 

The majority of the white finishes currently on the brick buildings at the Dry Tortugas Light Station 

appear to be modern acrylic- or oil-based paints. While the color of the finish is appropriate, the 

finish type is not. These modern finishes, which in some cases appear to be trapping moisture in the 

wall, should be removed and white limewash applied instead. Of course, care should be taken to 

carefully remove the modern paint layers in a way that does not damage the brick substrate (this 

would exclude the use of many abrasive blasting techniques). In addition, the existing paint should be 

tested to determine any lead content prior to removal. The materials analysis included in the 1984 

rehabilitation report cites that the paint on the exterior of the lighthouse is an acrylic-polyvinyl 

acetate mixture with lead and zinc-based pigments. It is likely this paint still remains on the lighthouse 
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 24

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

and that other buildings of the light station were painted with the same lead-based paint. Further

testing would be required to identify lead content in any of the paint coatings on the buildings.

Once the modern coatings are successfully removed from the brick masonry, the limewash will bond 

well to the brick, the mortar and any traces of earlier limewash. The limewash will allow any 

moisture present in the brick walls to escape without compromising the limewash finish (as opposed 

to the less permeable modern paints which can fail when moisture gets trapped behind them). 

Performing a mock-up of such a finish is strongly advised in order to assess the longevity of this type 

of finish in the environmental conditions associated with the island.

The only masonry surface that should not get painted with a lime wash is the top half of the day 

mark, which is painted black. Achieving a truly black limewash is difficult if not impossible, so some 

other type of finish will have to be used in this location. Although oil paints were most likely used 

historically, a better paint may be currently available. Modern paints such as those based on 

potassium silicate or even some highly permeable acrylic paints designed for historic masonry should 

be considered for the lighthouse.

WOODWORK & METALWORK

Recommendations for appropriate restoration finishes for the woodwork and metalwork of the oil 

house, lighthouse and keeper’s residence are included in the chart below; no paint colors are 

provided for the kitchen building because no historic paint was found on the wood trim of this 

building. Wherever surviving physical evidence remains, a color match to the historic paint color is 

provided. Color matches are made to both the Munsell and Benjamin Moore color systems. 

However, in cases where there is no longer any physical paint evidence or access to a particular 

element was not permitted during the study, recommendations for appropriate restoration colors 

are provided but are based solely on archival information (written or photographic). In the latter 

case, a general recommendation is provided but a specific color match is not. The basis for each 

color match is provided in the “Source” column of the chart below.

The recommended restoration paint colors are provided below. Specific color matches have been 

made to both the standardized Munsell color system and the commercial Benjamin Moore paint 

palette. CIE L*a*b values for the actual color as well as the color matches are also provided so that 

the difference between the actual color and the matches can be determined. Please note that, 

although there was subtle variation in the color of the limewashes on the different buildings, a single 

color match to the limewash is provided.

It should also be mentioned that the recommended colors for the lighthouse and oil house door trim 

(which are based on physical evidence) may represent original paint colors that were on the buildings 

when the brick masonry was exposed and not once the brick was painted white. Unfortunately, it is 
DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 25

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

not possible to determine the paint color on the wood door trim when the brick was first painted 

white.

Any attempt to reproduce the following pages, including printing from the electronic version of the 

report, will distort the color of the provided chips. Only the actual color chip or notation should be 

used for paint replication purposes.





DRY TORTUGAS LIGHT STATION. DRY TORTUGAS, FLORIDA. Page 31

Materials Analysis

BUILDING CONSERVATION ASSOCIATES INC August 2009

4.2 Mortar

Analysis of the brick mortars of the buildings at the Dry Tortugas Light Station indicates that the 

original mortars were composed of natural cement. Such mortars were typical for the period, 

especially for maritime construction. The mortar has generally held up well through the years, even 

in the harsh environment of wind and salt-laden sea air; although exceptions can be seen at the 

lighthouse, where the mortar is friable in many areas and paint loss occurs regularly at the mortar 

joints. However, as previously discussed, this deterioration is most likely a factor of moisture 

permeating through the wall and inappropriate paint films and not failure of the original material. A 

more comprehensive evaluation of this aspect of the masonry construction falls outside of the scope 

of this research.

For future re-pointing campaigns, it is important that the correct mortar be used. It may also be 

prudent to replace existing repair campaigns with a more appropriate mortar. Mortars based on 

large amounts of Portland cement are typically too strong and dense to be used in combination with 

the type of low-fired brick found on most of these buildings. Although, the keeper’s residence, which 

was built later, is an exception, as it is constructed of high-fired modern brick and Portland cement 

mortar. In general, the use of a high calcium or hydraulic lime mortar would also be inappropriate for 

these buildings. Therefore, the recommended restoration mortar for the historic buildings at the Dry 

Tortugas Light Station is as follows:

Lighthouse, Oil House, Kitchen Building & South Brick Cistern

Binder: natural cement 

Sand: natural carbonate sand (to match existing)

Component Ratio (binder: sand): 1:1.5

Keeper’s Residence

Binder: Portland cement

Sand: natural carbonate sand (to match existing)

Component Ratio (binder: sand): 1:3 (note this mix is slightly less binder-rich than the original)

APPENDIX A.

PHOTOMICROGRAPHS AND STRATIGRAPHIES

* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.1 (40x, Visible Light)

LOCATION: Oil House, exterior, east elevation now enclosed, finishes on brick.

LAYER* COLOR NOTES

Substrate Brick Surface looks weathered and soiled, suggests exposure 

prior to painting

1 Cream All finishes look like paint, missing early limewash layer 

visible in LOKE.F.9

2 Off-white

3 Off-white

4 Cream

5 Cream

6 Cream

7 Off-white

8 Cream

9 Off-white

10 Off-white

11 Off-white Current finish
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.2 (100x, Visible Light)

LOCATION: Passageway between Oil House & Lighthouse, south wall, finishes on concrete.

LAYER* COLOR NOTES

Substrate Concrete

1 Off-white

2 Cream

3 Cream

4 Off-white

5 Off-white Modern paint

6 Off-white Current finish
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.3 (40x, Visible Light)

LOCATION: Oil House, exterior, east elevationl, finishes on brick.

LAYER* COLOR NOTES

Substrate Brick Fracture at surface suggests weathering prior to painting

1 Cream

2 Cream

3 Cream

4 Cream

5 Cream

6 Cream

7 Cream

8 Cream

9 Cream

10 Cream/tan Translucent 

11 White

12 Off-white

13 Off-white

14 Off-white

15 White Current finish
SAMPLE NO: LOKE.F.4 (100x, Visible Light, only earliest layers visible in photo)

LOCATION: Oil House, exterior, east elevation, door frame, finishes on wood.

LAYER* COLOR NOTES

Substrate Wood

1 Pale gray

2 Pale gray

3 Pale gray

4 Gray-green Translucent 

5 Pale gray

6 Pale gray

7 Pale gray

8 Pale gray

9 Medium gray

10 Pale gray

11 Medium gray

12 Medium gray

13 Medium gray

14 Pale gray

15 Medium gray

16 Off-white
* bold indicates a finish layer and not a primer

17 Gray-green

18 Gray-green

19 Light gray-green

20 Pale gray

21 Off-white/ pale gray

22 Pale gray

23 Pale gray

24 Dark gray

25 Cream 

26 Off-white Remaining paints look more modern

27 Dark gray

28 Gray 

29 Blue-gray

30 White 

31 Dark gray

32 Cream

33 Cream

34 Cream

35 Cream

36 Cream

37 Cream

38 Cream

39 Gray

40 Olive green

41 Dark gray

42 White 

43 Dark gray

44 Dark gray

45 Dark gray

46 Light Gray

47 Gray Current finish
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.5 (100x, Visible Light)

LOCATION: Cistern, west elevation, finishes on brick.

LAYER* COLOR NOTES

Substrate Brick (missing in photo) No sign of weathering of brick surface, suggests brick was 

always finished

1 Off-white Translucent, white wash

2 Off-white Translucent, white wash

3 Off-white

4 Off-white Modern paint

5 White

6 White Current finish
SAMPLE NO: LOKE.F.6 (40x, Visible Light)

LOCATION: Lighthouse, exterior, north wall now enclosed adjacent to door, finishes on brick.

LAYER* COLOR NOTES

Substrate Brick Surface looks soiled

1 Tan Thin, translucent, lime wash

2 Cream

3 Tan Translucent 

4 Cream

5 Tan

6 Cream

7 Buff

8 Cream

9 White

10 Cream

11 Cream

12 Cream

13 Cream

14 Cream

15 Cream

16 Cream
17 Cream

18 Cream

19 Cream

20 [fracture]

21 White 

22 Light Green

23 Blue

24 Light Green

25 Blue

26 Dark Blue

27 Dark Blue

28 Gray

29 Gray

-blue

30 White Current finish
SAMPLE NO: LOKE.F.7 (40x, Visible Light)

LOCATION: Lighthouse, exterior, west wall now enclosed, door frame, finishes on wood.

LAYER* COLOR NOTES

Substrate Wood

1 Cream

2 Off-white

3 Off-white

4 Cream

5 Off-white 

6 Cream Translucent 

7 Off-white

8 Cream

9 Off-white

10 Dark green-gray Translucent 

11 Blue-gray

12 Dark blue-gray

13 Gray

14 Blue-gray

15 Light blue-gray

16 Light blue-gray

17 White 

18 Light blue-gray
* bold indicates a finish layer and not a primer

19 Light blue-gray

20 Blue-gray

21 Blue-gray

22 Dark blue-gray

23 Light blue-gray

24 Gray

25 Light gray

26 Gray

27 Blue-gray

28 Blue-gray

29 Blue-gray

30 Blue-gray

31 Blue-gray

32 Blue-gray

33 Blue-gray

34 Gray Thin 

35 Dark blue-gray

36 Blue-gray

37 White 

38 White 

39 Blue-gray

40 Light blue-gray

41 Gray Current finish
SAMPLE NO: LOKE.F.8 (100x, Visible Light, only earliest layers visible in photo)

LOCATION: Lighthouse, exterior, west wall now enclosed, door, finishes on wood.

LAYER* COLOR NOTES

Substrate Wood (not visible in photo)

1 Cream

2 Light gray

3 Light gray

4 Gray

5 Gray

6 Blue-gray

7 Gray

8 Blue-gray

9 Blue-gray

10 Blue-gray

11 Blue-gray

12 Light blue-gray

13 Light blue-gray

14 Dark blue-gray

15 Blue-gray

16 Blue-gray

17 White 

18 Blue-green
* bold indicates a finish layer and not a primer

19 Light blue-green

20 Blue-green

21 Blue-gray

22 Blue-gray

23 Blue-gray

24 Light blue-gray

25 Light blue-gray

26 Light green

27 Dark blue

28 Blue-gray

29 Light blue-gray

30 Gray Current finish
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.9 (40x, Visible Light)

LOCATION: Oil House, exterior, east wall, finishes on brick.

LAYER* COLOR NOTES

Substrate Brick Surface looks weathered

1 Cream Translucent, limewash

2 Cream Remaining layers look like paint

3 Cream

4 Cream Translucent material at surface

5 Cream

6 Off-white

7 Cream

8 Cream

9 Cream

10 White Translucent 

11 Cream

12 White Current Finish
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.10 (40x, Visible Light)

LOCATION: Kitchen Building, exterior, east elevation, finishes on brick.

LAYER* COLOR NOTES

Substrate Brick/Mortar

1 White All layers are modern paint

2 White

3 White

4 White

5 White Current Finish
SAMPLE NO: LOKE.F.11 (40x, Visible Light)

LOCATION: Oil House, exterior, south elevation now enclosed, finishes on brick.

LAYER* COLOR NOTES

Substrate Brick Surface is weathered, suggests exposure

1 Cream/tan Translucent, lime wash (partial layer)

2 Cream

3 Cream

4 Cream

5 Light cream

6 Cream

7 Cream

8 Cream

9 Cream

10 Cream

11 Cream

12 Cream

13 White

14 Off-white

15 White

16 Gray

17 Light gray

18 Light gray/off-white
* bold indicates a finish layer and not a primer

19 Off-white

20 Cream

21 Off-white

22 Light gray/off-white

23 Off-white

24 Green

25 Gray

26 Dark blue-gray

27 Light green

28 Green

29 Peach

30 White Current finish
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.12 (100x, Visible Light)

LOCATION: Keeper’s Dwelling, interior, hallway outside bathroom, west wall, finishes on plaster.

LAYER* COLOR NOTES

Substrate Plaster

1 Cream

2 White

3 Cream

4 Light green

5 Light green

6 White

7 Medium blue

8 Warm yellow

9 Medium green

10 Cream

11 White 

12 Cream

13 Light gray/beige

14 White 

15 Cream

16 White Current finish
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.13 (200x, Visible Light)

LOCATION: Keeper’s Dwelling, interior, hallway outside bathroom, cornice, finishes on wood.

LAYER* COLOR NOTES

Substrate Wood Sealed with clear coat

1 Cream

2 White

3 Cream

4 White

5 Cream

6 White

7 Cream Current finish
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.14 (100x, Visible Light)

LOCATION: Keeper’s Dwelling, interior, bathroom, west wall, finishes on plaster.

LAYER* COLOR NOTES

Substrate Plaster

1 Cream

2 White

3 Light Green

4 Light Gray

5 Gray

6 Blue

7 Warm cream

8 White

9 Light blue 

10 White

11 Light blue Current finish (behind drywall)
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.15 (100x, Visible Light)

LOCATION: Keeper’s Dwelling, exterior, east elevation, front door surround, finishes on wood.

LAYER* COLOR NOTES

Substrate Wood Surface distressed, looks stripped, missing earliest finish?

1 Dark green Soaked into pores of wood at surface

2 Cream 

3 White Thin 

4 Gray-green

5 White 

6 Dark red Thin 

7 Dark gray 

8 Dark red Disrupted, weathered

9 White

10 White Current finish 
* bold indicates a finish layer and not a primer

SAMPLE NO: LOKE.F.16 (40x, Visible Light)

LOCATION: Keeper’s Dwelling, exterior, east elevation, porch soffit (rear face), finishes on wood.

LAYER* COLOR NOTES

Substrate Wood

1 White

2 Cream Translucent 

3 White 

4 Cream

5 Off-white

6 Cream 

7 Cream

8 White

9 Cream 

10 White

11 White Current finish 

APPENDIX B.

MORTAR AND PLASTER ANALYSIS REPORT

(TESTWELL, INC. 2009)

TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 2 of 53 

Table of Contents 

1. Introduction 3 

2. Methods of Examination 3 

3. Petrographic Findings 4 

4. Point-Count Analyses 17 

5. Chemical Analyses 18 

5.1 Chemical Analysis Results 18 

5.2 Calculated Components 20 

6. Discussion and Conclusions 22 

6.1 Mortar Materials 22 

6.2 LOKE.M.10 Materials 24 

6.3 LOKE.M.8 Materials 24 

6.4 LOKE.M.11 Materials 25 

6.5 Cracking Distress and Salt Crystallization 26 

Appendix I: Photographs and Photomicrographs 27 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 3 of 53 

 

1. Introduction 

On March 27, 2009, Testwell received eleven mortar and plaster samples from Ms. Dorothy Krotzer of Building 

Conservation Associates, Inc. reported to have been sampled from various structures at the Loggerhead Key Light Station in 

the Dry Tortugas National Park, FL (Figs. 1 through 4). Samples are identified by the client as follows: 

Sample No. Building Description 

LOKE.M.1 Oil House Exterior, east elevation mortar. Taken from protected wall now enclosed. Sample 

from interior of wall (from an area where a hole was cut through wall for a pipe). 

LOKE.M.2 Brick Cistern Exterior, east elevation mortar. 

LOKE.M.3 Brick Cistern Interior, parging. Taken from upper portion of interior wall. 

LOKE.M.4 Lighthouse Exterior, west elevation, mortar. Taken approximately 8-feet from ground. 

LOKE.M.5 Lighthouse Exterior, west elevation, mortar. Taken from former exterior wall now enclosed, 

adjacent to entrance to lighthouse. 

LOKE.M.6 Lighthouse Interior, mortar. Taken from wall at ground floor level. 

LOKE.M.7 Lighthouse Interior, mortar. Taken from wall below watch level (supposedly rebuilt in 19th 

century). 

LOKE.M.8 Oil House Interior, south wall, plaster. Taken from behind modern wood paneling and earlier 

beadboard wall; three-layer plaster system applied over brick. 

LOKE.M.9 Kitchen Building Exterior, north elevation, mortar. Sample from interior of wall. 

LOKE.M.10 Keeper’s Dwelling Exterior, west wall, mortar. 

LOKE.M.11 Keeper’s Dwelling Interior, bathroom, west wall, plaster. Two-coat plaster system. 

At the client’s request, all samples are examined petrographically in order to identify material constituents and assess the 

degree of microcracking and associated mineral deposition. Aside from some of the plaster coats, all samples are also 

analyzed chemically in order to provide information regarding original binder chemistries and estimate original component 

proportions. Water-soluble chloride analysis is also requested for the four lighthouse mortar samples in order to provide 

information regarding possible salt crystallization or hydration distress. Finally, statistical point-count analysis is performed 

on three strategically chosen samples in order to provide a cross-check of the material proportion estimates generated from 

the chemical analyses. 

2. Methods of Examination 

The petrographic examination is conducted in accordance with the standard practices contained within ASTM C 1324: 

Standard Test Method for Examination and Analysis of Hardened Masonry Mortar. Data collection is performed by a 

degreed geologist who by nature of his/her education is qualified to operate the analytical equipment employed. Analysis 

and interpretation is performed or directed by a supervising petrographer who satisfies the qualifications as specified in 

Section 3 of ASTM C 856. 

Chemical analysis was conducted via a modification of the procedures outlined in ASTM C 1324: Standard Test Method for 

Examination and Analysis of Hardened Masonry Mortar. Water, carbon dioxide and aggregate weight percentages are 

determined gravimetrically. Oxide weight percentages are determined by atomic absorption spectroscopy. 

Statistical point counting was conducted in general accordance with the procedures outlined in ASTM C 457: Standard Test 

Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete. Sample sizes do not 

satisfy the minimum requirements outlined in the method and results are used as an approximate cross-check for other more 

quantitative methods. 

Water-soluble chloride analysis was performed in accordance with ASTM C 1218: Standard Test Method for Water-Soluble 

Chloride in Mortar and Concrete. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 4 of 53 

3. Petrographic Findings 

SAMPLE ID LOKE.M.1 (Oil House) 

GENERAL APPEARANCE 

Sample Type/Dimensions Multiple, irregular, mortar fragments weighing 17.91g. 

Surfaces One piece has two parallel sides that may be a joint surface. Approximately 0.5” thick. 

Hardness / Friability Moderately hard and non-friable. 

Appearance Luster on freshly exposed surfaces is dull. Fresh paste color is light gray (Munsell color designation approximately 

2.5Y 7/2). 

Cracks, Deposits, Etc., Cracking cannot be assessed due to the fragmental nature of the sample. No mineral deposits are observed. There is a 

low abundance of coal fragments detected. 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. Low abundance of opaques are also 

detected. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to 5Y 8/1). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 16 sieve 

with most material estimated to pass. Peak abundance is estimated between the No. 16 and No. 30 sieve and few fines 

are present below No. 50. 

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented though there is a somewhat preferential alignment of more elongate 

grains parallel or subparallel to the bed. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with moderate to moderately high capillary porosity on average. No 

significant calcium hydroxide as a cementitious hydrate is detected and the paste is almost completely carbonated. 

Residual Hydraulic Grains Natural cement relicts are found in moderate to moderately high abundance. These are fine to medium grained and 

generally carbonated in cross polarized light. Microtextures are varied but include typical calcined dolomite rhombs 

with rims of iron-bearing ferrite and distributed grains of partially combined quartz silt. Rimmed quartz silt is also 

commonly found as isolated grains within the paste matrix. No significant clinkered material is detected but there are 

traces of inert aluminate clusters. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 4% - 6% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are rounded and subspherical to irregular in shape on average. 

Secondary Deposits No secondary deposits are positively identified. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. No 

cracking or secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are moderately 

soft when scratched with a steel pick but do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details Trace microcracking is found along one edge of the sample in thin section. Otherwise, no significant macroscopic or 

microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 5 of 53 

SAMPLE ID LOKE.M.2 (Brick Cistern) 

GENERAL APPEARANCE 

Sample Type/Dimensions Multiple, irregular, mortar fragments weighing 26.79 g. 

Surfaces One piece has two parallel sides that may be a joint surface. Approximately 0.5” thick. 

Hardness / Friability Moderately hard and non-friable. 

Appearance Luster on freshly exposed surfaces is dull with some waxy areas where there are cement streaks. Fresh paste color is 

light gray (Munsell color designation approximately 2.5Y 7/2). 

Cracks, Deposits, Etc., Cracking cannot be assessed due to the fragmental nature of the sample. There is an adherent veneer of a white coating 

on many pieces. Sand grains are exposed below this wash indicating prior weathering. Low abundance of coal 

fragments are detected. 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. Low abundance of opaques are also 

detected. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to 5Y 8/1). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 16 sieve. 

Peak abundance is estimated between the No. 16 and No. 30 sieve and few fines are present below No. 50.

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented. Preferential alignment of more elongate grains are not obvious. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with moderate to moderately high capillary porosity on average. No 

significant calcium hydroxide as a cementitious hydrate is detected and the paste is almost completely carbonated. 

Residual Hydraulic Grains Natural cement relicts are found in moderate abundance. These are fine to medium grained and generally carbonated in 

cross polarized light. Microtextures are varied but include typical calcined dolomite rhombs with rims of iron-bearing 

ferrite and distributed grains of partially combined quartz silt. Rimmed quartz silt is also commonly found as isolated 

grains within the paste matrix. No significant clinkered material is detected but there are traces of inert aluminate 

clusters. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 3% - 5% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are rounded and subspherical to irregular in shape on average. 

Secondary Deposits No secondary deposits are positively identified. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. Minor 

abundance of microcracking found around aggregate paste interfaces. No secondary mineral deposits are found at 

aggregate interfaces. In honed section, interfaces are moderately soft when scratched with a steel pick but do not 

exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details Minor abundance of polygonal microcracking found passing through the paste and around aggregate paste interfaces. 

Some green-colored organic material is observed within cracks. No other significant macroscopic or microscopic 

cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 6 of 53 

SAMPLE ID LOKE.M.3 (Brick Cistern) 

GENERAL APPEARANCE 

Sample Type/Dimensions Multiple, irregular, parging mortar fragments weighing 97.83 g. 

Surfaces Approximately 0.25” - 0.5” in thickness. 

Hardness / Friability Moderately hard and non-friable. 

Appearance Luster on freshly exposed surfaces is dull. Fresh paste color is light brownish gray (Munsell color designation 

approximately 10YR 6/2). 

Cracks, Deposits, Etc., No significant cracking is detected in hand sample. Paste is in positive relief over the aggregate at the microscopic 

scale along the exposed surface. There is a low abundance of coal fragments detected. No mineral deposits are 

observed. 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. Low abundance of opaques are also 

detected. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to N8). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 16 sieve. 

Peak abundance is estimated between the No. 16 and No. 30 sieve and few fines are present below No. 50.

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented though there is a somewhat preferential alignment of more elongate 

grains parallel or subparallel to the bed. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with moderate to moderately high capillary porosity on average. The 

paste has a very slightly clumpy texture. No significant calcium hydroxide as a cementitious hydrate is detected and the 

paste is almost completely carbonated. 

Residual Hydraulic Grains Natural cement relicts are found in moderate abundance. These are fine to medium grained and generally carbonated in 

cross polarized light. Microtextures are varied but include typical calcined dolomite rhombs with rims of iron-bearing 

ferrite and distributed grains of partially combined quartz silt. Rimmed quartz silt is also commonly found as isolated 

grains within the paste matrix. No significant clinkered material is detected but there are traces of inert aluminate 

clusters. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 5% - 7% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are subrounded and subspherical to irregular in shape on 

average. 

Secondary Deposits Most voids are free of secondary deposits with only traces of sparry carbonate detected. 

AGGREGATE INTERFACES 

Details Sand grains are relatively well coated with binder. No variation in binder characteristics are found adjacent to 

aggregate. Moderate abundance of small discontinuous polygonal cracking found along aggregate paste interfaces. 

Secondary mineral deposits are found at aggregate interfaces in trace abundance as sparry carbonate. In honed section, 

interfaces are moderately soft when scratched with a steel pick but do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details Microscopic discontinuous hairline polygonal cracking detected in moderate abundance throughout the thin section. No 

other significant macroscopic or microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 7 of 53 

SAMPLE ID LOKE.M.4 (Lighthouse) 

GENERAL APPEARANCE 

Sample Type/Dimensions Multiple, irregular, mortar fragments weighing 24.14 g. 

Surfaces One piece has two parallel sides that may be a joint surface. Approximately 0.5” thick. 

Hardness / Friability Moderately hard and non-friable. 

Appearance Luster on freshly exposed surfaces is dull. Fresh paste color is light gray (Munsell color designation approximately 

2.5Y 7/2). 

Cracks, Deposits, Etc., Cracking cannot be assessed due to the fragmental nature of the sample. There is an adherent veneer of a white 

powdery coating on many pieces. There is a low abundance of coal fragments detected. 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. Low abundance of opaques are also 

detected. One chalcedony grain detected may belong to the cement. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to 5Y 8/1). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 16 sieve 

with most material estimated to pass. Peak abundance is estimated between the No. 16 and No. 30 sieve and few fines 

are present below No. 50. 

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented though there is a somewhat preferential alignment of more elongate 

grains parallel or subparallel to the bed. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with moderate capillary porosity on average. No significant calcium 

hydroxide as a cementitious hydrate is detected and the paste is mostly carbonated though some areas remain isotropic. 

Residual Hydraulic Grains Natural cement relicts are found in varied abundance with some mortar pieces exhibiting a high abundance. These are 

variously sized grains and are generally carbonated in cross polarized light. Microtextures are varied but include typical 

calcined dolomite rhombs with rims of iron-bearing ferrite and distributed grains of partially combined quartz silt. 

Rimmed quartz silt is also commonly found as isolated grains within the paste matrix. No significant clinkered material 

is detected but there are traces of inert aluminate clusters. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 4% - 6% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are irregular in shape on average. 

Secondary Deposits No secondary deposits are positively identified. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. No 

cracking or secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are moderately 

soft when scratched with a steel pick but do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, most portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details No significant macroscopic or microscopic cracking is detected. 

MISCELLANEOUS 

Details Opaque finishes are detected above a discontinuous microscopic veneer of depleted material in some areas of the 

perimeter. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 8 of 53 

SAMPLE ID LOKE.M.5 (Lighthouse) 

GENERAL APPEARANCE 

Sample Type/Dimensions Multiple, irregular, mortar fragments weighing 28.28 g. 

Surfaces All pieces exhibit irregular surfaces. 

Hardness / Friability Moderately hard and non-friable. 

Appearance Luster on freshly exposed surfaces is dull. Fresh paste color is light gray (Munsell color designation approximately 

2.5Y 7/2). 

Cracks, Deposits, Etc., Cracking cannot be assessed due to the fragmental nature of the sample. There is an adherent veneer of a white 

powdery coating on many pieces and a minor amount of adherent brick residue. There is a low abundance of coal 

fragments detected. 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. Low abundance of opaques are also 

detected. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to 5Y 8/1). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 16 sieve 

with most material estimated to pass. Peak abundance is estimated between the No. 16 and No. 50 sieve and 

moderately low amount of fines are present below No. 50. 

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented though there is a somewhat preferential alignment of more elongate 

grains parallel or subparallel to the bed. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with moderate to moderately high capillary porosity on average. No 

significant calcium hydroxide as a cementitious hydrate is detected and the paste is almost completely carbonated. 

Residual Hydraulic Grains Natural cement relicts are found in moderately low abundance. These are fine to medium grained and generally 

carbonated in cross polarized light. Microtextures are varied but include typical calcined dolomite rhombs with rims of 

iron-bearing ferrite and distributed grains of partially combined quartz silt. Rimmed quartz silt is also commonly found 

as isolated grains within the paste matrix. No significant clinkered material is detected but there are traces of inert 

aluminate clusters. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 4% - 6% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are irregular in shape on average. 

Secondary Deposits Most voids are free of secondary deposits. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. Zones of possible bleed water channels are found around some aggregate paste 

interfaces. Trace, small discontinuous cracks are found subparallel to the surface and passing around aggregates 

interfaces. No secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are moderately 

soft when scratched with a steel pick but do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other Traces of very fine grained deposits are found only within one microcrack surface and these have characteristics 

consistent with either sulfates or chlorites. 

CRACKING 

Details Small discontinuous cracks are found subparallel to the surface and passing around aggregates interfaces. Otherwise no

significant macroscopic or microscopic cracking is detected. 

MISCELLANEOUS 

Details A layer of lime wash is detected that is well bonded to the mortar. Lime wash appears to have two distinct layers. 

There is an opaque finish found above the lime wash. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 9 of 53 

SAMPLE ID LOKE.M.6 (Lighthouse) 

GENERAL APPEARANCE 

Sample Type/Dimensions Multiple, irregular, mortar fragments weighing 59.75 g. 

Surfaces One piece has two parallel sides that may be a joint surface. Approximately 0.5” thick. 

Hardness / Friability Moderately hard and non-friable. 

Appearance Luster on freshly exposed surfaces is dull. Fresh paste color is light gray (Munsell color designation approximately 

10YR 7/2). 

Cracks, Deposits, Etc., Cracking cannot be assessed due to the fragmental nature of the sample. There is an adherent veneer of a white 

powdery coating on many pieces and a minor amount of adherent brick residue. There is a low abundance of coal 

fragments detected. 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. Low abundance of opaques are also 

detected. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to 5Y 8/1). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 8 sieve with 

all material estimated to pass. Peak abundance is estimated between the No. 16 and No. 30 sieve and few fines are 

present below No. 50. 

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented though there is a somewhat preferential alignment of more elongate 

grains parallel or subparallel to the bed. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with moderate capillary porosity on average. No significant calcium 

hydroxide as a cementitious hydrate is detected and the paste is almost completely carbonated. 

Residual Hydraulic Grains Natural cement relicts are found in moderate to moderately high abundance. These are variously sized grains and are 

generally carbonated in cross polarized light. Microtextures are varied but include typical calcined dolomite rhombs 

with rims of iron-bearing ferrite and distributed grains of partially combined quartz silt. Rimmed quartz silt is also 

found as isolated grains within the paste matrix. No significant clinkered material is detected but there are traces of 

inert aluminate clusters. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 6% - 8% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than or equal to 1 mm in dimension. Voids are rounded and subspherical to irregular in shape 

on average. 

Secondary Deposits Most voids are free of secondary deposits. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. No 

cracking or secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are moderately 

soft when scratched with a steel pick but do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other A microscopically thin lining of isotropic, low relief secondary deposits tends to line the exterior surfaces of many of 

the mortar pieces. Some are also found within voids just adjacent to the surface but never in the interior. 

CRACKING 

Details No significant macroscopic or microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 10 of 53 

SAMPLE ID LOKE.M.7 (Lighthouse) 

GENERAL APPEARANCE 

Sample Type/Dimensions Multiple, irregular, mortar fragments weighing 42.36 g. 

Surfaces All pieces exhibit irregular surfaces. 

Hardness / Friability Moderately hard and non-friable. 

Appearance Luster on freshly exposed surfaces is dull. Fresh paste color is light gray (Munsell color designation approximately 

10YR 7/2). 

Cracks, Deposits, Etc., Cracking cannot be assessed due to the fragmental nature of the sample. No mineral deposits are observed. There is a 

low abundance of coal fragments detected. 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. Low abundance of opaques are also 

detected. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to 5Y 8/1). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 16 sieve. 

Peak abundance is estimated between the No. 16 and No. 30 sieve and few fines are present below No. 50. 

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented. Preferential alignment of more elongate grains is not obvious. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with moderate capillary porosity on average. No significant calcium 

hydroxide as a cementitious hydrate is detected and the paste is almost completely carbonated. 

Residual Hydraulic Grains Natural cement relicts are found in moderate to moderately high abundance. These are variously sized grains and are 

generally carbonated in cross polarized light. Microtextures are varied but include typical calcined dolomite rhombs 

with rims of iron-bearing ferrite and distributed grains of partially combined quartz silt. Rimmed quartz silt is also 

commonly found as isolated grains within the paste matrix. No significant clinkered material is detected but there are 

traces of inert aluminate clusters. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 3% - 5% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are rounded and subspherical to irregular in shape on average. 

Secondary Deposits No secondary deposits are positively identified. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. No 

cracking or secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are moderately 

soft when scratched with a steel pick but do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details No significant macroscopic or microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 11 of 53 

SAMPLE ID LOKE.M.8 (Oil House) 

GENERAL APPEARANCE 

Sample Type/Dimensions The sample represents a complete cross section of a three coat plaster system. One large piece and several smaller 

pieces were received from the interior, south wall weighing 40.17 g. The nominal thickness of the whole sample is 

0.75”. Three distinct material types are detected. Thicknesses of the three general layers is as follows: 

Scratch coat: approximately 1/8” 

Brown coat: approximately 3/8” 

Finish coat: approximately 1/8” 

Surfaces Contact surfaces are more or less planar. The scratch and finish coats are partially adhered to the brown coat. The 

finish coat disbonds easily along a relatively clean surface. 

Hardness / Friability Scratch coat: Moderately soft and moderately non-friable. 

Brown coat: Hard and non-friable. 

Finish coat: Moderately soft and moderately friable.

Appearance Scratch coat: Dull luster and nearly white on fresh exposure (Munsell color code approximately 5Y 8/1). 

Brown coat: Opaque waxy luster and light gray on fresh exposure (Munsell color code approximately 10YR 7/2). 

Finish coat: Moderately dull luster and bright white on fresh exposure (Munsell color code approximately N9). 

Cracks, Deposits, Etc., No significant cracking is visible in the larger sample though incipient disbonds may be present at layer contacts. No 

mineral deposits are observed. There is a low abundance of coal fragments detected within the brown coat. 

SAMPLE ID LOKE.M.8 (Oil House plaster scratch coat) 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9). The luster is dull. 

Size and Gradation The sand is medium-grained and narrowly graded. The nominal top size is estimated at the No. 8 sieve with all material 

estimated to pass. A strong peak abundance is estimated between the No. 16 and No. 30 sieves and only a moderately 

low abundance of material is estimated to pass the No. 30 sieve.

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented. Preferential alignment of more elongate grains is not obvious. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Homogeneous mildly hydraulic matrix with high capillary porosity on average and a moderate abundance of 

discontinuous polygonal microscopic cracks. 

Residual Hydraulic Grains Natural cement relicts are found in very low abundance. These are fine to medium grained and generally carbonated in 

cross polarized light. Microtextures are varied but include typical calcined dolomite rhombs with rims of iron-bearing 

ferrite and trace grains of partially combined quartz silt isolated within the paste matrix. 

Residual Lime Grains Low abundance of fine residual lime grains. Grains are fully carbonated with no internal relict rock textures or 

hydraulic inclusions. However, textures are difficult to assess due to a limited sample size. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 2% - 3% 

Consolidation / Distribution The plaster is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are rounded and subspherical in shape on average. 

Secondary Deposits No secondary deposits are positively identified. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. 

Discontinuous polygonal cracking is detected along some of the interfaces. Otherwise, no significant cracking or 

secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are soft when scratched with 

a steel pick. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details Discontinuous polygonal cracking. Otherwise, no significant macroscopic or microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 12 of 53 

SAMPLE ID LOKE.M.8 (Oil House plaster brown coat) 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. Low abundance of opaques are also 

detected. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to 5Y 8/1). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and narrowly graded. The nominal top size is estimated at the No. 8 sieve with all material 

estimated to pass. A strong peak abundance is estimated between the No. 16 and No. 30 sieves and only a moderately 

low abundance of material is estimated to pass the No. 30 sieve. 

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented though there is a somewhat preferential alignment of more elongate 

grains parallel or subparallel to the bed. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with moderate capillary porosity on average. No significant calcium 

hydroxide as a cementitious hydrate is detected and the paste is almost completely carbonated. 

Residual Hydraulic Grains Natural cement relicts are found in moderate to moderately high abundance. These are fine to medium grained though 

fines are much more abundant and are generally carbonated in cross polarized light. Microtextures are varied but 

include typical calcined dolomite rhombs with rims of iron-bearing ferrite and distributed grains of partially combined 

quartz silt. Rimmed quartz silt is also commonly found in high abundance as isolated grains within the paste matrix. 

No significant clinkered material is detected but there are traces of inert aluminate clusters. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 4% - 6% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are rounded and subspherical to irregular in shape on average. 

Secondary Deposits No secondary deposits are positively identified. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. No 

cracking or secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are moderately 

soft when scratched with a steel pick but do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details No significant macroscopic or microscopic cracking is detected. 

SAMPLE ID LOKE.M.8 (Oil House plaster finish coat) 

AGGREGATE 

Details No aggregate is present in the finish coat. 

BINDER MATRIX 

Hardened Binder Homogeneous mixed binder matrix with high capillary porosity and no significant microcracking. The matrix consists 

of a mixture of very fine grained, hydrated gypsum crystallites and fine mostly carbonated lime. 

Residual Hydraulic Grains None detected. 

Residual Lime Grains Residual lime grains are found in high abundance as fine- to medium grained particles. Most are fully carbonated 

though fully uncarbonated grains are also observed. Relict rock textures are rare and are difficult to interpret. 

However, these have the character of partially calcined silicate minerals. No evidence for significant hydraulic 

inclusions is observed. 

Residual Gypsiferous Grains Medium-grained gypsum relicts are relatively rare. Some of rehydrated to gypsum while some still represent 

unhydrated hemihydrate. Dead-burned anhydrite crystals are extremely rare. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 2% - 3% 

Consolidation / Distribution The plaster is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are irregular in shape on average. 

Secondary Deposits No significant secondary deposits are observed. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details No significant macroscopic or microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 13 of 53 

SAMPLE ID LOKE.M.9 (Kitchen Building) 

GENERAL APPEARANCE 

Sample Type/Dimensions Multiple, irregular, mortar fragments weighing 28.75 g. 

Surfaces One piece has two parallel sides that may be a joint surface. Approximately 0.5” thick. 

Hardness / Friability Moderately hard and non-friable. 

Appearance Luster on freshly exposed surfaces is dull. Fresh paste color is light gray (Munsell color designation approximately 

2.5Y 7/2). 

Cracks, Deposits, Etc., Cracking cannot be assessed due to the fragmental nature of the sample. There is an adherent veneer of a white coating 

on many pieces. There is a low abundance of coal fragments detected. 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. Low abundance of opaques are also 

detected. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to 5Y 8/1). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 16 sieve 

with most material estimated to pass. Peak abundance is estimated between the No. 16 and No. 30 sieve and few fines 

are present below No. 50. 

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented though there is a somewhat preferential alignment of more elongate 

grains parallel or subparallel to the bed. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with a moderately high to high capillary porosity. No significant calcium 

hydroxide as a cementitious hydrate is detected and the paste is almost completely carbonated. 

Residual Hydraulic Grains Natural cement relicts are found in moderate abundance. These are medium grained and generally carbonated in cross 

polarized light. Microtextures are varied but include typical calcined dolomite rhombs with rims of iron-bearing ferrite 

and distributed grains of partially combined quartz silt. Rimmed quartz silt is also commonly found as isolated grains 

within the paste matrix. No significant clinkered material is detected but there are traces of inert aluminate clusters. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 4% - 6% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are rounded and subspherical to irregular in shape on average. 

Secondary Deposits No secondary deposits are positively identified. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. No 

cracking or secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are moderately 

soft when scratched with a steel pick but do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details No significant macroscopic or microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 14 of 53 

SAMPLE ID LOKE.M.10 (Keeper’s Dwelling) 

GENERAL APPEARANCE 

Sample Type/Dimensions Multiple, irregular, mortar fragments weighing 32.83 g. 

Surfaces One piece has two parallel sides that may be a joint surface. Approximately 0.5” thick. There are weathered areas with 

a type of biological growth present in low abundance. 

Hardness / Friability Moderately hard and non-friable. 

Appearance Luster on freshly exposed surfaces is mostly dull, however the mortar does exhibit streaking and high variation. Fresh 

paste color is very pale brown (Munsell color designation approximately 10YR 8/2). 

Cracks, Deposits, Etc., Cracking cannot be assessed due to the fragmental nature of the sample. No mineral deposits are observed. 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. 

Appearance Viewed on weathered surfaces the sand is white in some cases and with a pale yellow hue (Munsell color code 

approximately N9 to 5Y 8/1). The luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 16 sieve 

with most material estimated to pass. Peak abundance is estimated between the No. 16 and No. 50 sieve and few fines 

are present below No. 50. 

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented. Preferential alignment of more elongate grains is not obvious. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Dense and homogeneous cementitious matrix with moderate to moderately high capillary porosity on average. No 

significant calcium hydroxide as a cementitious hydrate is detected and the paste is almost completely carbonated. 

Residual Hydraulic Grains Residual portland cement is detected in moderate abundance as medium grained belite agglomerates with interstitial 

ferrite. Virtually all grains are well hydrated and consist only of a ferrite “skeleton”. Alite forms are also detected 

within agglomerates in moderately low abundance. 

Residual Lime Grains None detected. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 3% - 5% 

Consolidation / Distribution The mortar is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are rounded and subspherical to irregular in shape on average. 

Secondary Deposits Some voids are lined with secondary deposits with optical characteristics consistent with gypsum. Otherwise most 

voids are free of secondary deposits. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. No 

cracking or secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are moderately 

hard when scratched with a steel pick and do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation In thin section, all portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details No significant macroscopic or microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 15 of 53 

SAMPLE ID LOKE.M.11 (Keeper’s Dwelling) 

GENERAL APPEARANCE 

Sample Type/Dimensions The sample represents a complete cross section of a two coat plaster system. Several pieces were received from the 

interior bathroom, west wall weighing 30.60 g. The nominal thickness of the whole sample is approximately 0.5 

including brown coat and finish coat. The brown coat is well bonded to the finish coat. A layer of paint is also detected 

on the finish coat. Approximate thicknesses of the two coats is as follows: 

Brown Coat: 3/8” 

Finish Coat: 1/8” 

Surfaces The contact surface is mostly planar and the two coats well bonded. 

Hardness / Friability Brown coat: Moderately hard and moderately non-friable. 

Finish coat: Moderately hard and non-friable. 

Appearance Brown coat: Luster on freshly exposed surfaces is dull. Fresh paste color is nearly white with a yellowish 

cast (Munsell color designation approximately 5Y 8.5/1). 

Finish coat: Luster on freshly exposed surfaces is dull. Fresh paste color is white (Munsell color designation 

approximately N9). 

Cracks, Deposits, Etc., No significant cracking, efflorescence, or secondary mineral deposits are detected in hand sample. However, cracking 

is difficult to assess due to the fragmental nature of the sample. A moderately low abundance of light-colored fiber 

reinforcement is identified in the brown coat. 

SAMPLE ID LOKE.M.11 (Keeper’s Dwelling plaster brown coat) 

AGGREGATE 

Lithology and Mode Carbonate natural sand consisting of shell fragments and porous coral fragments. 

Appearance The sand is white in most cases and with a pale yellow hue (Munsell color code approximately N9 to 5Y 8/1). The 

luster is slightly reflective to dull. 

Size and Gradation The sand is medium-grained and somewhat narrowly graded. The nominal top size is estimated at the No. 16 sieve 

with most material estimated to pass. Peak abundance is estimated between the No. 16 and No. 50 sieve and few fines 

are present below No. 50. 

Shape Subrounded in shape on average. Aspect ratios are subequant to subelongate. 

Distribution Homogeneous and somewhat randomly oriented though there is a somewhat preferential alignment of more elongate 

grains parallel or subparallel to the bed. 

Other No cracking, coatings, or chemical reactions are detected. 

BINDER MATRIX 

Hardened Binder Homogeneous gypsiferous matrix with high capillary porosity on average. While the matrix consists of an interlocking 

network of fine-grained gypsum crystals, the texture is somewhat coarse. 

Residual Hydraulic Grains None detected. 

Residual Lime Grains None detected. 

Residual Gypsiferous Grains A high abundance of medium-grained gypsum residuals are detected and almost all are fully hydrated to coarser grained 

gypsum. Finer unhydrated hemihydrate crystals are less common. There is moderately low abundance of very finegrained, dead burned anhydrite. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 8% - 10% 

Consolidation / Distribution The plaster is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than or equal to 1 mm in dimension. Voids are subspherical in shape on average. 

Secondary Deposits No significant secondary deposits are detected. 

AGGREGATE INTERFACES 

Details Sand grains are well coated with binder. No variation in binder characteristics are found adjacent to aggregate. No 

cracking or secondary mineral deposits are found at aggregate interfaces. In honed section, interfaces are moderately 

soft when scratched with a steel pick but do not exhibit any significant friability. 

SECONDARY REACTIONS 

Carbonation No carbonation is detected. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details No significant macroscopic or microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 16 of 53 

SAMPLE ID LOKE.M.11 (Keeper’s Dwelling plaster finish coat) 

AGGREGATE 

Details No aggregate is present in the finish coat. 

BINDER MATRIX 

Hardened Binder Homogeneous mostly gypsiferous matrix with high capillary porosity on average. The matrix consists of a network of 

ultrafine gypsum crystallites with a minor carbonated component. 

Residual Hydraulic Grains None detected. 

Residual Lime Grains Residual lime grains are found in very low abundance as fine-grained mostly carbonated particles. No internal rock 

textures or hydraulic inclusions are detected within lime grains. 

Residual Gypsiferous Grains A low abundance of fine-grained gypsum residuals are detected and almost all are fully hydrated to coarser grained 

gypsum. Finer unhydrated hemihydrate crystals and dead burned anhydrite are both relatively uncommon. 

Residual Pozzolans None detected. 

Pigments None detected. 

AIR-VOID SYSTEM 

Estimated Air Content Estimated at 2% - 4% 

Consolidation / Distribution The plaster is well consolidated and the air distribution is homogeneous. 

Size / Shape Voids are generally less than 1 mm in dimension. Voids are subspherical in shape on average. 

Secondary Deposits No significant secondary deposits are detected. 

SECONDARY REACTIONS 

Carbonation In thin section, the lime portions of the sample exhibit virtually full carbonation. 

Other No other evidence for chemical reaction is found within the bulk of the material. 

CRACKING 

Details No significant macroscopic or microscopic cracking is detected. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 17 of 53 

4. Point-Count Analyses

Point-count analysis was performed using methods adapted from ASTM C 457. Honed cross sections of the materials were 

prepared for the analysis. Sample LOKE.M.3 was chosen as a robust cross-check sample as sufficient material was available 

for both chemical analysis and point-count analysis. LOKE.M.4 and LOKE.M.7 were chosen for point-count analysis as 

these represent natural cement mortar samples with extremes in binder to sand ratio estimated via chemical analysis. It 

should be noted that that surface area of these latter two prepared samples and the number of points counted is smaller than 

required to produce the accuracy reported by the test method. 

Table 4.1 - Point-Count Data

Sample ID LOKE.M.3 LOKE.M.4 LOKE.M.7 

Location Cistern 

Exterior

Lighthouse 

Exterior

Lighthouse 

Interior

Approximate surface area (in.2

) 1.9 0.9 0.4 

Sand points 252 72 116 

Paste points 342 108 194 

Air-void points 34 12 13 

Total points 628 192 323 

Table 4.2 - Solid Volume Percentages

Sample ID LOKE.M.3 LOKE.M.4 LOKE.M.7 

Location Cistern 

Exterior

Lighthouse 

Exterior

Lighthouse 

Interior

Sand 40.1 37.5 35.9 

Paste 54.5 56.3 60.0 

Air-voids 5.4 6.2 4.0 

Totals 100.0 100.0 99.9

Table 4.3 - Calculated Bulk Ratios

Sample ID LOKE.M.3 LOKE.M.4 LOKE.M.7 

Location Cistern 

Exterior

Lighthouse 

Exterior

Lighthouse 

Interior

Sand volume percentage 56 53 50 

Cement volume percentage 44 47 50 

Cement : Sand Ratio (by volume) 1 : 1.3 1 : 1.1 1 : 1.0 

Notes: 

1) Solid volume of sand is adjusted by considering the void ratio of the sand in damp, loose condition. Paste volume is adjusted downward to account for 

the volume increase resulting from hydration of the cement. Counted sand volumes are divided by 0.62 to account for void space and paste volumes 

divided by 1.05 to account for volume increase upon hydration. 

2) Adjusted bulk volumes are normalized to 100% as presented in this table. 

3) Cement to sand ratios represent the ratios of these normalized values. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 18 of 53 

5. Chemical Analyses

The chemical preparations used on all samples with the exception of the finish coat plaster represent significant deviations 

from the standard procedures given in ASTM C 1324. The carbonate sand is exceptionally soluble in any acid capable of 

dissolving the binder and there is no effective way to separate the binder and sand effectively. Therefore, it was decided to 

fuse the sample into a glass, dissolve that in concentrated acid and measure the bulk chemistry of the entire sample. A 

separate acid digestion was performed in order to produce an insoluble residue. Instead of representing the sand, this residue

is used to examine the uncalcined inclusions within the natural cement binder. Water-soluble chloride was also measured for 

the Lighthouse samples and this was done in general accordance with ASTM C 1218. 

The analysis for the finish plaster also represents a deviation from ASTM C 1324 in that a hot acid digestion was used to 

bring all sulfate species into solution as well as all lime. These methods are more consistent with those of ASTM C 114 for 

the measurement of sulfates in cement. 

Table 5.1a: Chemical Analysis Results

SAMPLE ID LOKE.M.4 LOKE.M.5 LOKE.M.6 LOKE.M.7

Location Lighthouse 

Exterior 

Lighthouse 

Exterior 

Lighthouse 

Interior 

Lighthouse 

Interior 

Component (wgt. %) 

SiO2 7.06 8.63 8.34 10.26 

CaO 40.17 37.42 38.30 37.20 

MgO 6.97 7.65 7.18 5.63 

Al2O3 1.26 1.41 1.22 1.53 

Fe2O3 0.95 0.98 1.01 1.08 

Na2O 0.98 1.30 0.69 2.28 

K2O 0.08 0.38 0.65 1.01 

Cl 1.12 0.43 1.35 1.09 

Insoluble residue 1.35 3.09 2.53 5.26 

LOI %, to 110°C (Free water) 4.03 4.75 4.30 4.82 

LOI %, 110°C-550°C (Combined water) 8.48 9.75 8.32 10.04 

LOI %, 550°C-950°C (Carbon dioxide) 28.41 25.93 28.90 24.44 

Measured Totals 98.40 98.20 98.92 98.27 

Notes: 

1) The insoluble residue is not included in the totals calculation as it represents an intentional duplicate measurement. 

2) Chloride is also not included in the totals calculation nor is an adjustment made for the reduced oxygen that must accompany the alternate anion. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 19 of 53 

Table 5.1b: Chemical Analysis Results

SAMPLE ID LOKE.M.2 LOKE.M.3 LOKE.M.9 LOKE.M.10

Location Cistern 

Exterior 

Cistern 

Exterior 

Kitchen Bldg. 

Exterior 

Keeper’s 

Dwelling 

Component (wgt. %) 

SiO2 8.18 8.87 7.98 5.44 

CaO 42.03 40.07 40.24 45.67 

MgO 5.52 5.85 6.93 1.62 

Al2O3 1.71 1.58 1.40 1.27 

Fe2O3 1.07 1.07 1.31 0.68 

Na2O 0.34 0.31 0.35 0.36 

K2O 0.01 0.07 0.17 0.34 

Insoluble residue 2.33 3.09 2.90 0.72 

LOI %, to 110°C (Free water) 2.77 2.49 3.33 2.37 

LOI %, 110°C-550°C (Combined water) 5.27 4.19 7.67 6.19 

LOI %, 550°C-950°C (Carbon dioxide) 31.88 32.80 29.95 32.34 

Measured Totals 98.80 97.31 99.33 96.27 

Notes: 

1) The insoluble residue is not included in the totals calculation as it represents an intentional duplicate measurement. 

Table 5.1c: Chemical Analysis Results

SAMPLE ID LOKE.M.1 LOKE.M.8 LOKE.M.8

Location 

Oil House 

Exterior 

Oil House 

Plaster 

Brown Coat 

Oil House 

Plaster 

Finish Coat 

Component (wgt. %) 

SiO2 8.05 6.22 0.67 

CaO 40.05 41.20 45.20 

MgO 5.43 6.94 3.55 

Al2O3 1.83 1.33 0.15 

Fe2O3 1.09 1.13 0.14 

Na2O 1.18 0.61 0.79 

K2O 0.38 0.22 0.23 

SO3 n.d. n.d. 13.57 

Insoluble residue 2.70 4.03 0.00 

LOI %, to 110°C (Free water) 3.59 2.29 1.54 

LOI %, 110°C-550°C (Combined water) 7.60 9.01 7.70 

LOI %, 550°C-950°C (Carbon dioxide) 28.68 29.66 27.23 

Measured Totals 97.88 98.62 100.78 

Notes: 

1) The insoluble residue is not included in the totals calculation for the natural cement samples as it represents an intentional duplicate measurement. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 20 of 53 

Table 5.2a: Calculated Components

SAMPLE ID LOKE.M.4 LOKE.M.5 LOKE.M.6 LOKE.M.7

Location Lighthouse 

Exterior 

Lighthouse 

Exterior 

Lighthouse 

Interior 

Lighthouse 

Interior 

Component 

Portland cement (wgt. %) Not detected Not detected Not detected Not detected 

Natural cement (wgt. %) 32 41 39 47 

Lime expressed as dry hydrate (wgt. %) Not detected Not detected Not detected Not detected 

Hydraulic lime (wgt. %) Not detected Not detected Not detected Not detected 

Pozzolans (wgt. %) Not detected Not detected Not detected Not detected 

Mineral pigment (wgt. %) Not detected Not detected Not detected Not detected 

Sand (wgt. %) 68 59 61 53 

Binder : sand ratio (by volume) 1 : 2.0 1 : 1.4 1 : 1.5 1 : 1.1 

Table 5.2b: Calculated Components

SAMPLE ID LOKE.M.2 LOKE.M.3 LOKE.M.9 LOKE.M.10

Location Cistern 

Exterior 

Cistern 

Exterior 

Kitchen Bldg. 

Exterior 

Keeper’s 

Dwelling 

Component 

Portland cement (wgt. %) Not detected Not detected Not detected 33 

Natural cement (wgt. %) 35 39 36 Not detected 

Lime expressed as dry hydrate (wgt. %) Not detected Not detected Not detected Not detected 

Hydraulic lime (wgt. %) Not detected Not detected Not detected Not detected 

Pozzolans (wgt. %) Not detected Not detected Not detected Not detected 

Mineral pigment (wgt. %) Not detected Not detected Not detected Not detected 

Sand (wgt. %) 65 61 64 67 

Binder : sand ratio (by volume) 1 : 1.7 1 : 1.5 1 : 1.7 1 : 2.4 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 21 of 53 

Table 5.2c: Calculated Components

SAMPLE ID LOKE.M.1 LOKE.M.8 LOKE.M.8

Location Oil House 

Exterior 

Oil House Plaster 

Brown Coat 

Oil House Plaster 

Finish Coat 

Component 

Portland cement (wgt. %) Not detected Not detected Not detected 

Natural cement (wgt. %) 36 28 Not detected 

Lime expressed as dry hydrate (wgt. %) Not detected Not detected 68 

Hydraulic lime (wgt. %) Not detected Not detected Not detected 

Gypsum as hemihydrate (wgt. %) Not detected Not detected 32 

Pozzolans (wgt. %) Not detected Not detected Not detected 

Mineral pigment (wgt. %) Not detected Not detected Not detected 

Sand (wgt. %) 64 72 Not detected 

Binder : sand ratio (by volume) 1 : 1.7 1 : 2.4 n/a 

Gypsum : lime ratio (by volume with lime as a hydrate) n/a n/a 1 : 0.2 

Gypsum : lime ratio (by volume with lime as a putty) n/a n/a 1 : 0.3 

Notes: 

1) For the natural cement mortars, parging, and plaster coats, the cement weight is calculated assuming an original cement silica content of 27% and 

calcium oxide content of 35%. Cement content is calculated assuming all measured silica is attributed to this average natural cement composition. 

Excess calcium is then attributed to the carbonate sand and the equivalent weight of calcium carbonate is calculated by molecular weight conversion. 

Both calculated weights are then normalized to 100%. Volumetric ratios are calculated assuming bulk densities for natural cement and damp loose 

sand of 75 lb./cu. ft. and 80 lb./cu. ft. respectively. 

2) For the portland cement mortar (LOKE.M.10), the cement weight is calculated assuming an original cement silica content of 21% and calcium oxide 

content of 63%. Cement content is calculated assuming all measured silica is attributed to this average cement composition. Excess calcium is then 

attributed to the carbonate sand and the equivalent weight of calcium carbonate is calculated by molecular weight conversion. Both calculated weights 

are then normalized to 100%. Volumetric ratios are calculated assuming bulk densities for portland cement and damp loose sand of 94 lb./cu. ft. and 

80 lb./cu. ft. respectively. 

3) For the Oil House plaster finish coat (LOKE.M.8), the gypsum weight as hemihydrate is calculated by assuming that all measured sulfate is attributed 

to this component. Sufficient calcium oxide is taken up to account for this calculated gypsum component. The remaining calcium oxide and all 

magnesium oxide is attributed to the lime component and the mass is calculated by molecular weight conversion for both calcian and magnesian lime 

species. All calculated weights are then normalized to 100%. Volumetric ratios are calculated assuming bulk densities for dry gypsum plaster and dry 

lime hydrate of 93.5 lb./cu. ft. and 40 lb./cu. ft. respectively. A separate calculation is presented considering lime as a putty rather than a dry hydrate. 

This assumes an approximate 40% loss in bulk volume to turn a volume of dry lime hydrate into a stiff putty by addition of water. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 22 of 53 

6. Discussion and Conclusions

6.1 Mortar Materials 

All mortar samples are identified as pure cement mortars containing a natural carbonate sand (Figs. 5 through 15). 

Additionally, the brown coat of the Oil House plaster sample LOKE.M.8 is very similar and is grouped in this discussion for 

convenience. No lime-type binders, pozzolans, or mineral pigments are identified in any of these samples. Original water to 

cement ratios are difficult to assess due to the advanced age of the materials. However, variations in the quantity of cement 

relicts, differences in capillary porosity, and differences in lightness of the cement paste indicate relative differences in water 

to cement ratios between the samples. For the most part, the lighthouse samples exhibit slightly lower capillary porosities 

suggestive of a lower original water to cement ratio (Figs. 8 and 9). Sample LOKE.M.10 (Keeper’s Dwelling) differs in that 

the binder is a portland rather than natural cement and this sample will be discussed separately. Therefore, this discussion 

includes samples LOKE.M.1 through LOKE.M.7 as well as LOKE.M.9 and the brown coat of LOKE.M.8. 

The cement in these samples are all identified as American natural cements typical of those manufactured in the more 

productive cement regions such as Rosendale, NY or Louisville, KY. All unhydrated cement relicts exhibit microstructural 

properties consistent with the low-temperature calcination of an argillaceous and partly ferruginous dolomitic limestone. 

Such textures include fine-grained, calcined carbonate rhombs surrounded by a rim of iron-bearing phase as well as partly 

burned quartz silt and sand grains surrounded by a rim of hydraulic product (Figs. 12 through 15). While some variation is 

observed across all samples, the general cement characteristics are grossly similar. Furthermore, the chemical analysis of all

samples indicates a magnesium component no less than half that of the silica component and usually much more than this. 

Such chemistries are characteristic of the American natural cements and this clearly distinguishes them from a European 

product. Minor fine-grained coal fragments are also detected in most samples and these are interpreted to be contaminants 

from the cement burning. 

While difficult to ascertain different placement vintages based on cement characteristics, there are some subtle variations 

observed both petrographically and chemically that appear to group cements into similar batches or sources. Three of the 

four lighthouse samples (all but LOKE.M.5) exhibit a greater variation in the grind of the cement. All other samples exhibit 

a fine to medium grind but these three contain unhydrated cement relicts that are found as large as several hundred microns in 

dimension (Fig. 12). It is tempting to interpret this coarseness as representative of an earlier vintage but this would be purely 

speculative. The very slight difference in the sand gradation in LOKE.M.5 (discussed below) in addition to slightly different 

cement characteristics could suggest that this sample is not contemporaneous with the other lighthouse samples. It is also 

noted that some variation exists within the fragments of sample LOKE.M.4 (Fig. 9). Some portions of this sample exhibit 

cement characteristics more similar to those of the Oil House plaster brown coat (LOKE.M.8) rather than those of the other 

lighthouse samples . The distinctive texture here is a much greater abundance of very fine-grained, partially calcined quartz 

silt grains dispersed as isolated cement residuals throughout the paste (Fig. 13). The acid-insoluble residues measured 

chemically for both samples is also the highest in these two samples and this is consistent with the petrographic observation. 

The cement in these two samples is clearly of a different quality than the others and this has implications in the estimation of 

sand to binder ratios as discussed below. What is not clear based on examination of the fragments is the reason that 

LOKE.M.4 appears to contain two different types of cement within one sample. 

The sand in all samples is virtually identical with only subtle differences in gradation (Figs. 5 through 11). The sand is 

identified as a natural carbonate sand containing coral and shell fragments similar to that making up the sediment of the Dry 

Tortugas. A local source is certainly expected given the isolated nature of the site. No obviously crushed particles or foreign 

siliceous sands are identified that might suggest some modification to the local source. While it would be impossible to 

separate the sand from the binder through acid digestion, it is fairly clear through low-powered examination of fresh surfaces 

that the sand is homogeneous in color ranging from nearly white to pale yellow with no significant variegation. The grains 

are rounded due to natural weathering processes but tend to be somewhat elongate due to the original shapes of the 

organisms. All samples exhibit a relatively narrow sand gradation. Generally, all grains are estimated to pass a No. 8 sieve,

most passing No. 16, with a minor to a moderately low amount of grains estimated to pass the No. 50 sieve. With some 

minor exception, the samples exhibit a sharp peak abundance of material between the No. 16 and No. 30 sieves. Such narrow 

gradations within this size range make geological sense in beach zones subject to regular wave action. While the site sand 

was not examined for this report, it is fully expected from a geological perspective that the local material would match the 

observed gradations without further processing. 

Several subtle differences are detected in the sand gradations but these are very minor when compared to the general pattern. 

Some samples contain a slightly higher abundance of material retained on the No. 16 sieve. These include samples 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 23 of 53 

LOKE.M.2, M.3, M.6, M.7, M.8 and (brown coat). In two cases the nominal top size is estimated at the No. 8 rather than 

No. 16 sieve where it appears that more than 10% of the material is retained on No. 16. and these include samples LOKE.M.6 

and M.8. Some minor differences are also found in the fine end of the gradation. In most cases, minor material is estimated 

to pass the No. 50. A slightly higher abundance of fines is found in sample LOKE.M.5. The brown coat of sample 

LOKE.M.8 contains only a moderately low abundance of material estimated to pass the No. 30 sieve and is therefore even 

more narrowly graded. 

Generally speaking, all samples discussed in this section exhibit cement and sand components that are well mixed and 

distributed. Air contents tend to be low and the mortars are well consolidated. Hydration qualities of the cement are 

adequate with a homogeneous distribution of cementitious product. While some variation in original water to cement ratios 

are suggested by minor variations in capillary porosity (Figs. 8 through 11), all appear to have been mixed without an excess 

of water or significant retempering. 

Establishing original component proportions is challenging for this particular combination of sand and cement. Typically, a 

chemical methodology would be utilized whereby insoluble sand would be separated chemically for gravimetric 

measurement and the elemental chemistry of the dissolved binder component would be reverse engineered based on a fairly 

robust assumption of original binder chemistry. In this case, the sand is completely soluble and original natural cement 

chemistries are more variable than those of American portland cements or limes. Two analytical options are available to 

overcome these complications. The first is a microscopical point-counting of sand and binder components on polished slabs 

of the mortar. This method is insensitive to variations in the original binder chemistry and only measures paste and sand 

volume. The second is a complete fusion, or bulk chemical analysis of the mortar. Analysis of this chemistry requires an 

assumption of the original binder chemistry in order to partition the binder portion. This is followed by a calculation of the

sand based on the remaining calcium unaccounted for by the binder partitioning. The former method may be considered 

more robust but requires a relatively large sample in order to be statistically significant. As such large sized samples were 

not available, it was agreed in discussions with the client that the chemical analysis that requires a smaller sample would be 

performed on all samples. The point-count method is then performed on sample LOKE.M.3 as a large sample is available. 

Comparison of the independent results is then expected to inform how well the chemical analysis may estimate the 

proportions. Additional point-counts on less than adequate samples are then performed on mortar samples estimated to 

exhibit extremes of binder to sand ratios based on the chemistry. These are performed on sample LOKE.M.4 and 

LOKE.M.7. A summary of the estimates are given in the table below based on bulk volume. 

Sample ID Cement to sand ratio

by chemical analysis 

Cement to sand ratio

by point-count analysis 

LOKE.M.1 1 : 1.7 n.d. 

LOKE.M.2 1 : 1.7 n.d. 

LOKE.M.3 1 : 1.5 1 : 1.3 

LOKE.M.4 1 : 2.0 1 : 1.1 

LOKE.M.5 1 : 1.4 n.d. 

LOKE.M.6 1 : 1.5 n.d. 

LOKE.M.7 1 : 1.1 1 : 1.0 

LOKE.M.8 (brown coat) 1 : 2.4 n.d. 

LOKE.M.9 1 : 1.7 n.d. 

Some interesting features are revealed particularly in light of the qualitative petrographic observations. First, the independent 

methods result in good agreement for the binder to sand ratio in sample LOKE.M.3. This suggests that the assumption of 

original natural cement chemistry is relatively effective at estimating ratios from the bulk chemical analysis. Similar 

agreement is found in sample LOKE.M.7 even though the point-count sample is smaller than might be desired for statistical 

significance. Interestingly, the chemical analysis of samples LOKE.M.4 and M.8 result in a higher sand content calculation 

than the other mortars yet such variation is not evident by qualitative petrographic observations where all sand contents 

appear more or less similar. These are the two samples where the characteristics of the relict cement grains are distinctly 

different than the others in the suite with a high abundance of partially burned quartz silt. Point-count analysis of LOKE.M.4

suggests half the sand content as that estimated from the chemical analysis. It is interpreted that the original cement 

chemistry is different in these samples and the proportions estimated via the chemical analysis may represent an 

overestimation of sand content for these two. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 24 of 53 

Based on these analyses, it is interpreted that most binder to sand ratios are approximately 1 : 1.5 by volume. Samples 

LOKE.M.4 and LOKE.M.7 may be closer to 1 : 1. Such low sandings with narrow and relatively coarse sand gradations are 

considered typical of historical natural cement mortars. If in-kind replication is a priority, mix designs with these proportions 

and gradations may be considered viable. 

6.2 LOKE.M.10 Materials 

The exterior mortar of the Keeper’s dwelling (LOKE.M.10) appears identical to the other mortars based on visual 

characteristics and is also identified as a pure cement mortar (Figs. 6 and 10). However, the binder is identified as a pure 

portland cement with no lime additions identified. The distinctive low-magnesium, low insoluble residue values measured 

chemically are consistent with this qualitative identification. Cement relicts are identified petrographically as medium-sized

agglomerates of well-hydrated calcium silicates with interstitial ferrite (Fig. 14). The iron-bearing ferrite identifies the binder 

as an ordinary gray portland cement. The medium grind and homogeneity of calcium silicate size is consistent with cements 

produced in the early twentieth century and is considered consistent with the early 1920’s vintage reported by the client. 

The sand in this sample is identical in composition and only slightly different in gradation as that observed in the natural 

cement mortars discussed above. As with these, the sand is a natural carbonate sand consistent with the local source (Figs. 6 

and 10). The appearance of the sand is also homogenous and light-colored ranging from nearly white to pale yellow. The 

grains are rounded due to natural weathering processes but tend to be somewhat elongate due to the original shapes of the 

organisms. The gradation is still narrow with a nominal top size estimated at the No. 16 sieve but the peak abundance is 

estimated to be spread more evenly between the No. 16 and No. 50 sieves as compared to other samples in the suite. Still, 

there are relatively few fines in the sand estimated to pass the No. 50 sieve size. As with the other samples, this relatively

narrow gradation is considered geologically consistent with the local sediment. 

LOKE.M.10 exhibits cement and sand components that are well mixed and distributed. Air contents tend to be low and the 

mortar well consolidated. Hydration qualities of the cement are virtually complete with a homogeneous distribution of 

cementitious product. The original water to cement ratio is estimated to be moderate based on the observed capillary porosity 

and the mortar appears to have been mixed without an excess of water or significant retempering (Fig. 10). 

Chemical analysis was performed in order to estimate the original binder to sand ratios. In this case, an estimate based on 

chemical analysis is considered more robust as portland cement has a less variable chemistry than natural cement. Assuming 

a typical portland cement chemistry and bulk densities of cement and damp, loose sand, the binder to sand ratio is estimated 

at 1 : 2.4. The sand content is higher than that observed in the other natural cement mortars but this is considered consistent 

with historic practice. 

6.3 LOKE.M.8 Materials 

LOKE.M.8 is reported to represent an Oil House plaster sample and consists of a three-coat plaster system (Figs 16 through 

20). Substrate is not included with the sample. The sample includes a relatively soft and porous scratch coat identified as a

sanded, lime-based plaster gauged with natural cement, a relatively hard and dense brown coat identified as a sanded, pure 

natural cement plaster, and a fine-textured, unsanded finish coat consisting of lime gauged with gypsum. Generally speaking, 

these materials are considered consistent with a mid-nineteenth century vintage and certainly are inconsistent with twentieth 

century practice. The use of gypsum-based plaster as a gauging material is less well understood. While the use of calcined 

gypsum as a binder has a long history, the author is unaware of any American references to its use in the States prior to 

approximately 1880. 

The sand in the scratch and brown coats is more or less identical (Fig. 7). As discussed earlier for the brown coat, the 

aggregate is identified as a natural carbonate sand containing coral and shell fragments similar to that making up the sediment

of the Dry Tortugas. Visual examination indicates a homogeneous color ranging from nearly white to pale yellow with no 

significant variegation. Grains are rounded due to natural weathering processes but tend to be somewhat elongate due to the 

original shapes of the organisms. The gradation is quite narrow with a nominal top size estimated at the No. 8 sieve with all 

material estimated to pass. A strong peak abundance is estimated between the No. 16 and No. 30 sieves with only a 

moderately low abundance of material estimated to pass the No. 30 sieve. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 25 of 53 

The binder matrix in the scratch coat is characterized by a highly porous, carbonated paste, with a moderate abundance of 

microscopic shrinkage cracks. The paste matrix is typical of a high lime binder (Fig. 16). Larger relict lime grains are 

observed in low abundance and these exhibit homogeneous internal textures. Given the limited sample available for the 

scratch coat, it is not possible to speculate on the source of the lime. Furthermore, a chemical analysis could not be 

performed and no information is available for the lime chemistry. Natural cement grains identical to those of the brown coat 

are found in very low abundance (Fig. 17). The cement is estimated to represent a minor gauging affording only minimal 

hydraulic property to the scratch coat. While no quantitative estimate is offered, it is unlikely that the cement represents 

more than one tenth part of the lime by volume. The sanding is interpreted to be relatively low based on petrographic 

observations and the binder to sand ratio is probably less than 1 : 2 by volume. 

Due to the similarity of the brown coat to the natural cement mortars, more detail for this layer is provided above. The binder 

matrix is moderately dense and consists of a natural cement binder with no lime addition. The cement is identified as a 

magnesium natural cement consistent in texture with the more productive American manufactories. However, a higher 

abundance of calcined silt is observed than in any of the other mortar samples with the exception of portions of sample 

LOKE.M.4. Chemical analysis was performed on this sample and binder to sand ratio estimated at 1 : 2.4 by volume. 

However, based on arguments presented earlier, this is likely a significant overestimate due to a distinctly different chemistry 

for this cement. Petrographic similarity of this sample with those of the other mortar samples suggest that the actual ratio 

may be closer to 1 : 1.5. 

The finish coat matrix is fine-textured and porous (Fig. 19). An abundance of fine residual lime grains indicates the layer is

mostly lime based. Chemical analysis was performed on this layer. Even assuming that all magnesium is contained in the 

lime, a CaO/MgO weight ratio of 10 (an order of magnitude higher than an ideal dolomitic ratio of 1.4) suggests a high 

calcium rather than dolomitic lime. Traces of calcined silicate contaminants suggest a rock lime source but not enough 

material is observed petrographically to offer a definitive statement. Gypsum plaster is identified as a gauging material (Fig. 

20). Very few unhydrated gypsum relicts are identified. The rare abundance of coarser hemihydrate or finer dead-burned 

anhydrite suggests that the plaster was not a cement plaster or Keene’s cement but rather a fine finishing plaster such as 

Plaster-of-Paris. 

Chemical analysis was performed on the finish coat in order to estimate the lime to plaster proportions. Assuming the lime 

was added as a dry hydrate, the lime to plaster ratio is estimated at 1 : 0.2. It is unlikely that the lime was a prepackaged 

hydrate. However, a given volume of dry hydrate has a more constant weight ratio of constituent elements than a given 

volume of putty and the estimate may be considered more robust. Assuming a similar mass of hydrate loses approximately 

40% of its volume when mixed with water to the consistency of a stiff putty, the ratio is recalculated at 1 : 0.3 by volume. 

6.4 LOKE.M.11 Materials 

LOKE.M.11 is reported to represent an Keeper’s Dwelling plaster sample and consists of a two-coat plaster system (Figs. 21 

through 24). Substrate is not included with the sample. The sample includes a relatively hard but porous brown coat 

identified as a sanded, gypsum-based plaster and a relatively hard but porous, unsanded finish coat consisting of a finetextured gypsum gauged with lime. The use of gypsum materials rather than lime for interior plastering is considered 

consistent with the 1920’s vintage reported by the client. 

The brown coat contains a relatively coarse-textured and porous binder matrix composed of a network of fine-grained 

gypsum hydrate (Fig. 21). Coarser hydrated residuals are relatively common and unhydrated hemihydrate and fine-grained, 

dead-burned anhydrite are also present though in lower abundance (Fig. 22). A chemical analysis was not requested for this 

sample and further information regarding the plaster provenance cannot be provided. However, the microtexture of the coat 

clearly discounts a refined finishing plaster and the presence of the dead-burned gypsum (anhydrite) suggests that the plaster 

may have been a Keene’s cement. It should be noted that the term “cement” here does not refer to hydraulic calcium silicates 

and Keene’s cement represents a relatively pure calcium sulfate product. 

The sand in the brown coat is identical to that of the other samples in the suite and is most similar to the other Keeper’s 

Dwelling sample (LOKE.M.10) in gradation (Figs. 7 and 21). The aggregate is identified as a natural carbonate sand 

containing coral and shell fragments similar to that making up the local sediment. Visual examination indicates a 

homogeneous color ranging from nearly white to pale yellow with no significant variegation. Grains are rounded due to 

natural weathering processes but tend to be somewhat elongate due to the original shapes of the organisms. The gradation is 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 26 of 53 

somewhat narrow with a nominal top size estimated at the No. 16 sieve. The peak abundance is estimated between the No. 

16 and No. 50 sieves with only a minor abundance of material estimated to pass the No. 50 sieve. 

The finish coat matrix is fine-textured and moderately porous. The paste matrix is dominated by a network of very-fine 

grained hydrated gypsum crystallites (Fig. 23). Very few unhydrated gypsum relicts are identified. The rare abundance of 

coarser hemihydrate or finer dead-burned anhydrite suggests that the plaster was not a cement plaster or Keene’s cement but 

rather a fine finishing plaster such as Plaster-of-Paris (Fig. 24). A very low abundance of carbonated lime grains are 

dispersed throughout the largely gypsum-based matrix. While a chemical analysis was not performed for this sample, the 

lime is interpreted to represent a minor gauging rather than a major component of the finish plaster. 

6.5 Cracking Distress and Salt Crystallization 

The client requested some discussion regarding the possible role of salts as a deleterious agent in the examined suite of 

samples. A combination of petrographic and chemical techniques are utilized in order to address this concern. 

First, it is noted that while some samples are provided in fragmental condition, very little internal microcracking is detected

in the majority of the samples (Fig. 25). Most exhibit good microstructural integrity. Some minor to moderate 

microcracking is detected in the cistern samples (LOKE.M.2 and M.3) and some minor microcracking is found in the 

Lighthouse sample LOKE.M.5. It should be stated that while minor salt deposits are detected within some of these cracks 

and other samples have chemistries suggestive of some soluble salt content, there is no evidence suggesting that any sample 

in the suite has undergone any deterioration related to either salt crystallization or salt hydration distress (Fig. 26). Minor 

sulfate deposits are observed petrographically in sample LOKE.M.5 as well as fine deposits likely to represent chloride salts 

based on their optical character. Similar salts consistent with chlorides are found as minor thin surface linings in sample 

LOKE.M.6. The greatest amount of secondary sulfate as gypsum is found within air-voids of sample LOKE.M.10. This is 

not surprising as this is the only sample containing a portland cement binder with hydrates more susceptible to secondary 

gypsum recrystallization. Even here however, the deposits are not related to any significant cracking distress. 

The alkali elements sodium and potassium were measured quantitatively for all samples analyzed chemically. These are 

somewhat elevated for most samples. Additionally, water-soluble chloride was measured for the four Lighthouse samples 

and these may also be considered slightly elevated in content. However, it is likely that the local carbonate sand was 

unwashed prior to mixing and was rich in soluble alkali salts (particularly chlorides). It is also noted that no natural 

freshwater sources are present in the Dry Tortugas and all freshwater would have to have been collected by cistern systems. 

Given the scarcity of freshwater, it is also likely that the mortars were mixed with saltwater. A greater proportion of the 

alkali content is more likely to be related to the original mix constituents rather than later contamination. It is interesting to 

note that the cistern samples (LOKE.M.2 and M.3) exhibit the lowest alkali contents. Given the application, these mortars 

and pargings likely had a greater exposure to freshwater through drinking water storage and the reduced alkali content may 

be related to leaching and dilution of original chloride salts. 

TESTWELL, INC.

John J. Walsh 

Senior Petrographer/ Geologist 

Samples will be discarded 30 days after the final report date unless otherwise instructed. This report is the confidential property of the 

client and any unauthorized reproduction is strictly prohibited. The interpretations and conclusions presented in this report are based on 

the samples provided.
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 27 of 53 

Appendix I: Photographs and Photomicrographs

Microscopic examination is performed on an Olympus BX-51 polarized/reflected light microscope and a Bausch and Lomb 

Stereozoom 7 stereoscopic reflected light microscope. Both microscopes are fitted with an Olympus DP-11 digital camera. 

The overlays presented in the photomicrographs (e.g., text, scale bars, and arrows) are prepared as layers in Adobe Photoshop 

and converted to the jpeg format. Digital processing is limited to those functions normally performed during standard print 

photography processing. Photographs intended to be visually compared are taken under the same exposure conditions 

whenever possible. 

The following abbreviations may be found in the figure captions and overlays and these are defined as follows: 

cm centimeters PPL Plane polarized light 

mm millimeters XPL Crossed polarized light 

m microns (1 micron = 1/1000 millimeter) 

mil 1/1000 inch 

Microscopical images are often non-intuitive to those not accustomed to the techniques employed. The following is offered 

as a brief explanation of the various views encountered in order that the reader may gain a better appreciation of what is 

being described. 

Reflected light images: These are simply magnified images of the surface as would be observed by the human eye. A 

variety of surface preparations may be employed including polished and fractured surfaces. The reader should note the 

included scale bars as minor deficiencies may seem much more significant when magnified. 

Plane polarized light images (PPL): This imaging technique is most often employed in order to discern textural 

relationships and microstructure. To employ this technique, samples are milled (anywhere from 20 to 30 microns depending 

on the purpose) so as to allow light to be transmitted through the material. In many cases, Testwell also employs a technique 

whereby the material is impregnated with a low viscosity, blue-dyed epoxy. Anything appearing blue therefore represents 

some type of void space (e.g.; air voids, capillary pores, open cracks, etc.) Hydrated cement paste typically appears a light 

shade of brown in this view (with a blue hue when impregnated with the epoxy). With some exceptions, most aggregate 

materials are very light colored if not altogether white. Some particles will appear to stand out in higher relief than others. 

This is a function of the refractive power of different materials with respect to the mounting epoxy. 

Crossed polarized light images (XPL): This imaging technique is most often employed to distinguish components or 

highlight textural relationships between certain components not easily distinguished in plane polarized light. Using the same 

thin sections, this technique places the sample between two pieces of polarizing film in order to determine the crystal 

structure of the materials under consideration. Isotropic materials (e.g.; hydrated cement paste, pozzolans and other glasses,

many oxides, etc.) will not transmit light under crossed polars and therefore appear black. Non-isotropic crystals (e.g.; 

residual cement, calcium hydroxide, calcium carbonate, and most aggregate minerals) will appear colored. The colors are a 

function of the thickness, crystal structure, and orientation of the mineral. Many minerals will exhibit a range of colors due

to their orientation in the section. For example, quartz sand will appear black to white and every shade of gray in between. 

Color differences do not necessarily indicate material differences. When no other prompt is given in the figure caption, the 

reader should appeal to general shapes and morphological characteristics when considering the components being illustrated. 

Chemical treatments: Many chemical techniques (etches and stains typically) are used to isolate and enhance a variety of 

materials and structures. These techniques will often produce strongly colored images that distinguish components or 

chemical conditions. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 28 of 53 

 

 

Figure 1: Photographs of the four Lighthouse mortar samples as received by Testwell for examination. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 29 of 53 

 

 

Figure 2: Photographs of mortar samples from the cistern, Kitchen Building and Keeper’s Dwelling as received by Testwell for 

examination. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 30 of 53 

 

 

Figure 3: Photographs of the samples from the Oil House as received by Testwell for examination. Sample LOKE.M.8 is a plaster 

sample. A top view (top right) and rear view (bottom left) show the scratch coat (SC), brown coat (BC), and finish coat (FC) in this threecoat plaster. The last photograph presents a side view. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 31 of 53 

Figure 4: Photographs of the plaster sample from the Keeper’s Dwelling as received by Testwell for examination. The bottom 

photograph presents a side view of the two-coat plaster with brown coat (BC) and finish coat (FC) visible. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 32 of 53 

 

 

Figure 5: Reflected light photomicrographs of honed cross sections of the Lighthouse mortar samples. Binder matrix is well compacted 

and consolidated around sand grains (S). The sand is light-colored and homogeneous and the same type of sand component is found in all 

samples. Gradations tend to be relatively narrow with all material estimated to pass a No. 8 sieve and little material found below the No. 

50 sieve. Blue coloration in some of the samples is due to the impregnation of a low-viscosity blue dyed epoxy. Several of the honed 

sections were prepared directly from residual thin section billets where total sample size is small. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 33 of 53 

 

 

Figure 6: Reflected light photomicrographs of honed cross sections of mortar samples from the cistern, Kitchen Building and Keeper’s 

Dwelling. Binder matrix is well compacted and consolidated around sand grains (S). The sand is light-colored and homogeneous and the 

same type of sand component is found in all samples. Gradations tend to be relatively narrow with all material estimated to pass a No. 8 

sieve and little material found below the No. 50 sieve. Blue coloration in some of the samples is due to the impregnation of a low-viscosity 

blue dyed epoxy. Several of the honed sections were prepared directly from residual thin section billets where total sample size is small.
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 34 of 53 

 

 

Figure 7: Reflected light photomicrographs of honed cross sections of samples from the Oil House and sanded plaster coats. Binder 

matrix is well compacted and consolidated around sand grains (S). The sand is light-colored and homogeneous and the same type of sand 

component is found in all samples. Gradations tend to be relatively narrow with all material estimated to pass a No. 8 sieve and little 

material found below the No. 50 sieve. Blue coloration in some of the samples is due to the impregnation of a low-viscosity blue dyed 

epoxy. Several of the honed sections were prepared directly from residual thin section billets where total sample size is small.
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 35 of 53 

 

Figure 8: PPL photomicrographs illustrating the overall microstructure of the Lighthouse mortar samples. Sample LOKE.M.4 is not 

shown here and is presented in the next figure. The hydraulic binder matrix (BM) is well developed. Porosities tend to be moderate for the 

Lighthouse samples and this is demonstrated by the relatively low absorption of blue-dyed epoxy used in the sample preparation. The sand 

(S) is well coated with binder and is identified as a soft, natural carbonate sand composed of a variety of coral and shell fragments. Airvoids (AV) are not abundant. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 36 of 53 

Figure 9: PPL photomicrographs illustrating the overall microstructure of Sample LOKE.M.4. Sample LOKE.M.4 is unusual in that two 

different microtextures are found within the same sample. The top image shows a binder matrix (BM) that has a higher porosity than the 

one in the image below. This is shown by the difference in absorption of blue-dyed epoxy used in the sample preparation. The binder 

matrix in the lower image also has a “grittier” character. This is interpreted to be due to a difference in the cement for this portion of the 

sample. The feature is shown in greater detail in Figure 13 below. The sand (S) has the same characteristics as that of the other Lighthouse 

samples. Air-voids (AV) are not abundant. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 37 of 53 

 

 

Figure 10: PPL photomicrographs illustrating the overall microstructure of mortar samples from the cistern, Kitchen Building and 

Keeper’s Dwelling. The hydraulic binder matrix (BM) is well developed. Porosities tend to be moderate to moderately high for these 

samples and this is demonstrated by the moderate absorption of blue-dyed epoxy used in the sample preparation. Sample LOKE.M.9 has a 

high porosity in some areas of the sample. The sand (S) is well coated with binder and is identified as a soft, natural carbonate sand 

composed of a variety of coral and shell fragments. Air-voids (AV) are not abundant. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 38 of 53 

Figure 11: PPL photomicrographs illustrating the overall microstructure of the Oil House samples. The brown coat is shown for 

LOKE.M.8 as this material is more or less identical to that of the masonry mortar samples. The hydraulic binder matrix (BM) is well 

developed. Porosities tend to be moderately high for LOKE.M.1 and moderate for the brown coat of LOKE.M.8 samples and this is 

demonstrated by variations in the absorption of blue-dyed epoxy used in the sample preparation. The sand (S) is well coated with binder 

and is identified as a soft, natural carbonate sand composed of a variety of coral and shell fragments. The brown coat contains the coarsest 

sand of all examined samples and this is evident in this photomicrograph. Air-voids (AV) are not abundant in either sample. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 39 of 53 

 

 

Figure 12: PPL photomicrographs illustrating binder residuals in the Lighthouse mortar samples. All are identified as natural cement 

relicts (NC). Typical textures within these grains include calcined dolomite rhombs surrounded by an iron-rich hydraulic product and 

partially burned quartz silt grains evenly dispersed throughout the particles. These textures are characteristic of magnesium-rich American 

cements of the nineteenth century. With the exception of sample LOKE.M.5, the Lighthouse samples tend to have more variably-sized 

cement relicts with coarse grains not uncommon. This is different than other samples in the suite and may suggest a different cement batch 

or source for these three mortars. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 40 of 53 

Figure 13: PPL photomicrographs illustrating distinctive cement microtextures in portions of LOKE.M.4 and all of the brown coat in 

LOKE.M.8. The arrows exhibit isolated fine silt grains dispersed throughout the paste matrix. These are not a component of the sand as 

closer inspection reveals fine calcination rims around these grains. Such calcined quartz silt is a common component of natural cements 

and in fact, these are found in all the natural cement mortars examined for this report. However, the abundance is distinctively high in 

these two samples suggesting a different cement batch or source. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 41 of 53 

 

 

Figure 14: PPL photomicrographs illustrating binder residuals in mortar samples from the cistern, Kitchen Building and Keeper’s 

Dwelling. All but those in LOKE.M.10 (Keeper’s Dwelling) are identified as natural cement relicts (NC). Typical textures within these 

grains include calcined dolomite rhombs surrounded by an iron-rich hydraulic product and partially burned quartz silt grains evenly 

dispersed throughout the particles. These textures are characteristic of magnesium-rich American cements of the nineteenth century. 

Residual cement tends to fine- to medium-grained. The residual binder in LOKE.M.10 is identified as an ordinary gray portland cement 

(PC). The grain shown here contains rounded “ghosts” of fully hydrated calcium silicate with interstitial iron-bearing cement phases. The 

grind and consistency of the cement is characteristic of early twentieth century portlands. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 42 of 53 

Figure 15: PPL photomicrographs illustrating binder residuals in some of the Oil House samples. The brown coat is shown for 

LOKE.M.8 as this material is more or less identical to that of the masonry mortar samples. All are identified as natural cement relicts 

(NC). Typical textures within these grains include calcined dolomite rhombs surrounded by an iron-rich hydraulic product and partially 

burned quartz silt grains evenly dispersed throughout the particles. These textures are characteristic of magnesium-rich American cements 

of the nineteenth century. Residual cement tends to fine- to medium-grained. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 43 of 53 

Figure 16: PPL photomicrograph illustrating the overall microstructure of the scratch coat in sample LOKE.M.8. The binder matrix 

(BM) has a high capillary porosity as indicated by the high absorption of blue-dyed epoxy used in the sample preparation. Fine shrinkage 

cracks are also detected within the matrix and these two features are characteristics of high-lime binder matrices. The sand (S) is the same 

soft, natural carbonate sand found in the mortar samples. Air-voids (AV) are moderately abundant. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 44 of 53 

Figure 17: Photomicrographs illustrating binder residuals in the scratch coat in sample LOKE.M.8. (Top) XPL image. A lime grain 

(LG) is shown. The internal texture of the lime is homogeneous and little evidence is provided that might suggest the provenance of the 

lime. (Bottom) PPL image. A natural cement relict is shown (NC). These have the same characteristics as other cements in the sample 

suite. The cement is present in low abundance and is estimated to represent a minor gauging of an otherwise non-hydraulic lime plaster. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 45 of 53 

Figure 18: PPL photomicrograph illustrating the contact between the scratch coat (SC) and brown coat (BC) in LOKE.M.8. While 

natural cement (NC) is present in both, the difference in binder texture between a lime plaster gauged with cement (left) and a pure cement 

plaster (right) is quite apparent and difficult to mistake. Other details of the brown coat are presented above and are not repeated here. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 46 of 53 

Figure 19: PPL photomicrograph illustrating the overall microstructure of the finish coat in sample LOKE.M.8. The binder matrix (BM) 

has a high capillary porosity as indicated by the high absorption of blue-dyed epoxy used in the sample preparation. The layer is unsanded 

and all grains observed here are part of the binder. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 47 of 53 

 

Figure 20: Photomicrographs illustrating binder residuals in the finish coat in sample LOKE.M.8. (Top) XPL image. Lime grains (LG) 

are found in high abundance. Chemical analysis indicates that the finish is principally a lime plaster with a moderate gypsum gauging. 

The darker appearance of the grain at left indicates that it has not carbonated. The brighter grain at right is carbonated as are most observed 

residuals. (Bottom left) A gypsum residual (G) represents a grain of originally unhydrated hemihydrate that has hydrated to coarser 

grained gypsum. (Bottom right) This gypsum residual (GR) contains residual unhydrated hemihydrate. Both types of residual are 

relatively rare in this fine-textured plaster coat. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 48 of 53 

Figure 21: PPL photomicrographs illustrating the overall microstructure of the brown coat in sample LOKE.M.11. (Top) The binder 

matrix (BM) has a high capillary porosity as indicated by the high absorption of blue-dyed epoxy used in the sample preparation. The sand 

(S) is the same soft, natural carbonate sand found in the mortar samples. Air-voids (AV) are moderately abundant. (Bottom) The matrix is 

defined by a network of fine hydrated gypsum crystals. Still, the texture is somewhat coarse when compared to the finish coat (Fig. 23 

below) and the plaster in this coat may have been a Keene’s cement. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 49 of 53 

Figure 22: XPL photomicrographs illustrating binder residuals in the brown coat of sample LOKE.M.11. Gypsum residuals (G) represent 

grains of originally unhydrated hemihydrate that has hydrated to coarser grained gypsum. The arrow indicates a fine crystal of deadburned anhydrite. This type of inclusion is typical of Keene’s cement and would not be abundant in a Plaster-of-Paris. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 50 of 53 

Figure 23: PPL photomicrographs illustrating the overall microstructure of the finish coat in sample LOKE.M.11. (Top) The binder 

matrix (BM) has a high capillary porosity as indicated by the high absorption of blue-dyed epoxy used in the sample preparation. The layer 

is unsanded and all grains observed here are part of the binder. (Bottom) The matrix is defined by a network of fine hydrated gypsum 

crystals. Even in this higher magnification image, the texture is difficult to see and the finish coat plaster is much finer textured. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 51 of 53 

Figure 24: Photomicrographs illustrating binder residuals in the finish coat in sample LOKE.M.11. (Top) XPL image. Gypsum 

residuals (G) represent grains of originally unhydrated hemihydrate that have hydrated to coarser grained gypsum. The arrow indicates an 

unhydrated hemihydrate residual. Both types of residual are relatively rare in this fine-textured plaster coat. (Bottom) A carbonated lime 

grain is shown (LG). While chemical analysis was not performed on this sample, the lime is interpreted to represent a very minor gauging 

based on its observed abundance. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 52 of 53 

 

Figure 25: PPL photomicrographs illustrating microcracks in the cistern samples and one of the Lighthouse samples (arrows). These are 

minor and no sample in the examined suite exhibits any significant cracking distress. 
TESTWELL, INC. 

Building Conservation Associates, Inc.; Loggerhead Key Light Station 

Report #: OPCL011/PGE-001 

Page 53 of 53 

 

Figure 26: PPL photomicrographs illustrating the few secondary chemical deposits detected petrographically in the examined sample 

suite. No visible distress is associated with any of these deposits. (Top left) Isotropic mineral deposits consistent with chlorides (Cl) are 

found in low abundance in samples LOKE.M.5 and LOKE.M.6. (Top right) Fine secondary deposits consistent with sulfates (S) are quite 

rare. (Bottom) Some air-voids in the portland cement mortar of sample LOKE.M.10 contain linings of secondary gypsum but again, no 

associated distress is noted.
APPENDIX C.

REHABILITATION REPORT AND NATIONAL REGISTER NOMINATION 

FOR THE UNITED STATED COAST GUARD LIGHT STATION

DRY TORTUGAS LIGHTHOUSE, LOGGERHEAD KEY, FLORIDA

(1984)































APPENDIX C 

Various Specifications, Descriptions and 

Materials List for Keeper’s Residence 

















As the nation’s principal conservation agency, the 

Department of the Interior has responsibility for most 

of our nationally owned public lands and natural 

resources. This includes fostering sound use of our 

land and water resources; protecting our fish, wildlife, 

and biological diversity; preserving the environmental 

and cultural values of our national parks and 

historical places; and providing for the enjoyment of 

life through outdoor recreation. The department 

assesses our energy and mineral resources and works 

to ensure that their development is in the best 

interests of all our people by encouraging stewardship 

and citizen participation in their care. The 

department also has a major responsibility for 

American Indian reservation communities and for 

people who live in island territories under U.S. 

administration. 

NPS 364/105055 August 2010