19 PRESERVATION 

BRIEFS 

The Repair and Replacement of 

Historic Wooden Shingle Roofs 

Sharon C. Park, AlA 

u.s. Department of the Interior, National Park Service 

Preservation Assistance Division, Technical Preservation Services 

The Secretary of the Interior's "Standards for Rehabilitation" call for the repair or replacement of missing architectural features "based on 

accurate duplication of features, substantiated by historic, physical, or pictorial evidence rather than on conjectural designs." On a 

wooden shingle roof, it is important not only to match the size, shape, texture, and configuration of historic shingles, but also to match 

the craftsmanship and details that characterize the historic roof. Proper installation and maintenance will extend the life of the new roof. 

Introduction 

Wooden shingle roofs are important elements of many 

historic buildings. The special visual qualities imparted 

by both the historic shingles and the installation patterns 

should be preserved when a wooden shingle roof is 

replaced. This requires an understanding of the size, 

shape, and detailing of the historic shingle and the 

method of fabrication and installation. These combined 

to create roofs expressive of particular architectural 

styles, which were often influenced by regional craft 

practices. The use of wooden shingles from the early 

settlement days to the present illustrates an extraordinary range of styles (see illus. 1, 2, 3, 4). 

Wooden shingle roofs need periodic replacement. 

They can last from 15 to over 60 years, but the shingles 

should be replaced before there is deterioration of other 

wooden components of the building. Appropriate replacement shingles are available, but careful research, 

design, specifications, and the selection of a skilled 

roofer are necessary to assure a job that will both preserve the appearance of the historic building and extend the useful life of the replacement roof. 

Unfortunately, the wrong shingles are often selected 

or are installed in a manner incompatible with the appearance of the historic roof. There are a number of 

reasons why the wrong shingles are selected for replacement roofs. They include the failure to identify 

the appearance of the original shingles; unfamiliarity 

with available products; an inadequate budget; or a 

confusion in terminology. In any discussion about historic 

roofing materials and practices, it is important to understand the historic definitions of terms like "shingles;' as well as the modern definitions or use of those 

terms by craftsmen and the industry. Historically, from 

the first buildings in America, these wooden roofing 

products were called shingles, regardless of whether 

they were the earliest handsplit or the later machinesawn type . The term shake is a relatively recent one, 

and today is used by the industry to distinguish the 

sawn products from the split products, but through 

most of our building history there has been no such 

distinction. 

Considering the confusion among architects and 

others regarding these terms as they relate to the appearance of early roofs, it should be stated that there is 

a considerable body of documentary information about 

historic roofing practices and materials in this country, 

and that many actual specimens of historic shingles 

from various periods and places have been collected 

and preserved so that their historic appearances are 

well established. Essentially, the rustic looking shake 

that we see used so much today has little in common 

with the shingles that were used on most of our early 

buildings in America. 

Throughout this Brief, the term shingle will be used 

to refer to historic wooden roofs in general, whether 

split or sawn, and the term shake will be used only 

when it refers to a commercially available product. The 

variety and complexity of terminology used for currently available products will be seen in the accompanying chart entitled "Shingles and Shakes." 

This Brief discusses what to look for in historic 

wooden shingle roofs and when to replace them. It 

discusses ways to select or modify modern products to 

duplicate the appearance of a historic roof, offers guidance on proper installation, and provides information 

on coatings and maintenance procedures to help preserve the new roof. * 

(*Preservation Brief 4: Roofing for Historic Buildings discusses 

research methods, analysis of deterioration, and the general significance of historic roofs.) 
Wooden Shingle Roofs in America 

Because trees were plentiful from the earliest settlement days, the use of wood for all aspects of construction is not surprising. Wooden shingles were 

lightweight, made with simple tools, and easily installed. Wooden shingle roofs were prevalent in the 

Colonies, while in Europe at the same time, thatch, 

slate and tile were the prevalent roofing materials. Distinctive roofing patterns exist in various regions of the 

country that were settled by the English, Dutch, Germans, and Scandinavians. These patterns and features 

include the size, shape and exposure length of shingles, special treatments such as swept valleys, combed 

ridges, and decorative butt end or long side-lapped 

beveled handsplit shingles. Such features impart a 

special character to each building, and prior to any 

restoration or rehabilitation project the physical and 

photographic evidence should be carefully researched 

in order to document the historic building as much as 

1. The Rolfe-Wa"en House, a tidewater Virginia property, was restored to its 

18th-century appearance in 1933. The handsplit and dressed wooden shingles are typical of the tidewater area with special features such as curoed 

butts, projecting ridge comb and closed swept valleys at the dormer roof 

connections. Circa 1970 Photo: Association for the Preservation of Virginia 

Antiquities. 

3. Readily available and inexpensive sawn shingles were used not only for 

roofs, but also for gables and wall surfaces. The circa 1891 Chambers House, 

Eugene, Oregon used straight sawn butts for the majority of the roof and 

hexagonal butts for the lower portion of the corner tower. Decorative shingles in the gable ends and an attractive wooden roof cresting feature were 

also used. Photo: Lane County Historical Society. 

2 

possible. Care should be taken not to assume that aged 

or deteriorated shingles in photographs represent the 

historic appearance. 

Shingle Fabrication. Historically wooden shingles were 

usually thin (3/8" -3/4"), relatively narrow (3" -8"), of 

varying length (14" -36"), and almost always smooth .. 

The traditional method for making wooden shingles m 

the 17th and 18th centuries was to handsplit them from 

log sections known as bolts (see illus. SA). These bolts 

were quartered or split into wedges. A mallet and froe 

(or ax) were used to split or rive out thin planks of 

wood along the grain. If a tapered shingle was desired, 

the bolt was flipped after each successive strike with 

the froe and mallet. The wood species varied according 

to available local woods, but only the heartwood, or 

inner section, of the log was usually used. The softer 

sapwood generally was not used because it deteriorated quickly. Because handsplit shingles were somewhat irregular along the split surface, it was necessary 

2. Handsplit and dressed shingles were also used on less elaborate buildings 

as seen in the restoration of the circa 1840 kitchen at the Winedale Inn, 

Texas. The uneven surfaces of the handsplit shingles were generally dressed 

or smoothed with a draw-knife to keep the rainwater from collecting in the 

wood grain and to ensure that the shingles lay flat on the sub-roof. Photo: 

Thomas Taylor. 

4. With the popularity of the revival of historic styles in the late 19th and 

early 20th centuries, a new technique was developed to im~tate English. 

thatch roofs. For the Tudor Revival thatch cottages, steammg and curomg of 

sawn shingles provided an undulating pattern to this picturesque roof shape. 

Photo: Courtesy of c.H. Roofing. 
to dress or plane the shingles on a shavinghorse with a 

draw-knife or draw-shave (see illus. 5B) to make them 

fit evenly on the roof. This reworking was necessary to 

provide a tight-fitting roof over typically open shingle 

lath or sheathing boards: Dressing, or smoothing of 

shingles, was almost universal, no matter what wood 

was used or in what part of the country the building 

was located, except in those cases where a temporary 

or very utilitarian roof was needed. 

Shingle fabrication was revolutionized in the early 

19th century by steam-powered saw mills (see illus. 6). 

Shingle mills made possible the production of uniform 

shingles in mass quantities. The sawn shingle of uniform taper and smooth surface eliminated the need to 

hand dress. The supply of wooden shingles was therefore no longer limited by local factors. These changes 

coincided with (and in turn increased) the popularity 

of architectural styles such as Carpenter Gothic and 

Queen Anne that used shingles to great effect. 

Handsplit shingles continued to be used in many 

places well after the introduction of machine sawn 

shingles. There were, of course, other popular roofing 

materials, and so,rne regions rich in slate had fewer 

examples of wooden shingle roofs. Some western 

5. Custom Handsplit shingles are still made the traditional way with a mallet and froe or ax. For these cypress shingles, a "bolt" section of log (photo A) the length 

of the shingle has been sawn and is ready to be split into wedge-shaped segments. Handsplit shingles are fabricated with the ax or froe cutting the wood along the 

grain and separating, or riving, the shingle away from the remaining wedge. The rough surfaces are dressed on a shavinghorse using a draw-knife as shown above 

(photo B). Note the long wooden shingles covering the wark shed in photo A. Photos: Al Honeycutt, North Carolina Division of Archives and History. 

6. Modern machine-made shingles are sawn. Shown are: (photo A) Eastern White Pine quarter split shingle block on equalizer saw being trimmed to parallel the 

ends; and (photo B) the restored 19th-century shingle mill saw cutting tapered flitches or shingles. The thickness and taper can be precisely controlled. Photo: Steve 

Ruscio, The Shingle Mill. 

3 
"boom" towns used sheet metal because it was light 

and easily shipped. Slate, terneplate, and clay tile were 

used on ornate buildings and in cities that limited the 

use of flammable wooden shingles. Wooden shingles, 

however, were never abandoned. Even in the 20th century, architectural styles such as the Colonial Revival 

and Tudor Revival, used wooden shingles. 

Modern wooden shingles, both sawn and split, continue to be made, but it is important to understand 

how these new products differ from the historic ones 

and to know how they can be modified for use on historic buildings. Modern commercially available shakes 

are generally thicker than the historic handsplit counterpart and are usually left "undressed" with a rough, 

corrugated surface. The rough surface shake, furthermore, is often promoted as suitable for historic preservation projects because of its rustic appearance. It is an 

erroneous assumption that the more irregular the shingle, the more authentic or "historic" it will appear. 

Historic Detailing and Installation Techniques. While 

the size, shape and finish of the shingle determine the 

roof's texture and scale, the installation patterns and 

details give the roof its unique character. Many details 

reflect the craft practices of the builders and the architectural style prevalent at the time of construction. 

Other details had specific purposes for reducing moisture penetration to the structure. In addition to the 

most visible aspects of a shingle roof, the details at the 

rake boards, eaves, ridges, hips, dormers, cupolas, 

gables, and chimneys should not be overlooked. 

The way the shingles were laid was often based on 

functional and practical needs. Because a roof is the 

most vulnerable element of a building, many of the 

roofing details that have become distinctive features 

were first developed simply to keep water out. Roof 

combs on the windward side of a roof protect the ridge 

line. Wedges, or cant strips, at dormer cheeks roll the 

water away from the vertical wall. Swept valleys and 

fanned hips keep the grain of the wood in the shingle 

parallel to the angle of the building joint to aid water 

7. The reshingling of the cirrn 1856 Stovewood House in Decorah, Iowa, 

revealed the original open sheathing boards and pole rafters. Sawn cedar 

shingles were used as a replacement for the historic cedar shingles seen still 

in place at the ridge. A new starter course is being laid at the eaves. Photo: 

Norwegian-American Museum, Decorah, Iowa. 

4 

""'"'-"""'OWOO'c 

TYPIa.L Dn'AI~STALLAnoN Of toNG IIA){lA1,D.TAn:lEO SHINCLlS 

8. The long biaxially tapered handsplit shingles on the Ephrata Cloisters in 

Pennsylvania were overlapped both vertically and horizontally. The insert 

sketch shows channels under the shingles that provided ventilation and 

drainage of any trapped moisture. The aged appearance of these handsplit 

and dressed shingles belies their original smoothness. Replacement shingles 

should match the original, not the aged appearance. Photo: National Park 

Service; Sketch: Reed Engle. 

9. This 1927 view of the reshingling of the French Castle at Old Fort Niagara, N. Y., shows the wooden sleepers being laid (see arrow) over solid 

sheathing in order to raise the shingles up slightly to allow under-shingle 

ventilation. Note that the horiwntal strips are not continuous to allow 

airflow and trapped moisture to drain away. This cedar roof has lasted for 

over 60 years in a harsh moist environment. Photo: Old Fort Niagara, 

Assoc. Inc. 
WOODEN SHINGLES-HISTORIC DETAILS AND INSTALLATION PATTERNS 

Shingle Patterns 

.1 • 1 .1 .1 • 

I \ 1 

Long biaxiallytapered, sidelapped 

Ridges 

Traditional 

overlap 

Projecting 

comb 

Alternating 

closed 

ridge 

Boston 

c~pped L-~~ ____________ ~ ndge 

Hips 

Traditional alternating 

shingle hip 

Boston capped 

hip 

Fancy butts 

(fishscales shown) 

Board 

ridge 

Rolled 

metal 

ridge 

cover 

Wooden 

crest 

Rolled metal 

hip cover 

Staggered 

overfap 

Steamed & bent 

"thatch" 

Closed 

swept 

valley 

Open 

valley with 

wooden 

wedge 

Open 

valley with 

metal 

flashing 

Fanned or swirled 

alternating shingle hip 

10. The Historic Details and Installation Patterns Chart illustrates a number of special features found on wooden roofs. Documented examples of these features, 

different for every building and often reflecting regional variations, should be accurately reproduced when a replacement roof is installed. Chart: Sharon C. Park; 

delineation Uy Kaye Ellen Simonson. 

5 
run-off. The slight projection of the shingles at the 

eaves directs the water run-off either into a gutter or off 

the roof away from the exterior wall. These details varied from region to region and from style to style. They 

can be duplicated even with the added protection of 

modern flashing. 

In order to have a weathertight roof, it was important 

to have adequate coverage, proper spacing of shingles, 

and straight grain shingles. Many roofs were laid on 

open shingle lath or open sheathing boards (see illus. 

7). Roofers typically laid three layers of shingles with 

approximately 1/3 of each shingle exposed to the 

weather. Spaces between shingles (1/8" -1/2" depending on wood type) allowed the shingles to expand 

when wet. It was important to stagger each overlapping shingle by a minimum of 1-1/2" to avoid a direct 

path for moisture to penetrate a joint. Doubling or tripling the starter course at the eave gave added protection to this exposed surface. In order for the roof to lay 

as flat as possible, the thickness, taper and surface of 

the shingles was relatively uniform; any unevenness on 

handsplit shingles had already been smoothed away 

with a drawknife. To keep shingles from curling or 

cupping, the shingle width was generally limited to 

less than 10". 

Not all shingles were laid in evenly spaced, overlapping, horizontal rows. In various regions of the country, there were distinct installation patterns; for 

example, the biaxially-tapered long shingles occasionally found in areas settled by the Germans (see illus. 

8). These long shingles were overlapped on the side as 

well as on top. This formed a ventilation channel under 

the shingles that aided drying. Because ventilation of 

the shingles can prolong their life, roofers paid attention to these details (see illus. 9). 

Early roofers believed that applied coatings would 

protect the wood and prolong the life of the roof. In 

many cases they did; but in many cases, the shingles 

were left to weather naturally and they, too, had a long 

life. Eighteenth-century coatings included a pine pitch 

coating not unlike turpentine, and boiled linseed oil or 

fish oil mixed with oxides, red lead, brick dust, or 

other minerals to produce colors such as yellow, Venetian red, Spanish brown, and slate grey. In the 19th 

century, in addition to the earlier colors, shingles were 

stained or painted to complement the building colors: 

Indian red, chocolate brown, or brown-green. During 

the Greek Revival and later in the 20th century with 

other revival styles, green was also used. Untreated 

shingles age to a silver-grey or soft brown depending 

on the wood species. 

The craft traditions of the builders often played an 

important role in the final appearance of the building. 

The Historic Details and Installation Patterns Chart (see 

illus. 10) identifies many of the features found on historic wooden roofs. These elements, different on each 

building, should be preserved in a re-roofing project. 

Replacing Deteriorated Roofs: 

Matching the Historic Appearance 

Historic wooden roofs using straight edgegrain heartwood shingles have been known to last over sixty 

years. Fifteen to thirty years, however, is a more realistic lifespan for most premium modern wooden shingle 

roofs. Contributing factors to deterioration include the 

6 

11. The replacement sawn red cedar shingles matched the deteriorated shingles exactly for this barn re-roofing. The old shingles, seen to the far left, were removed as the new shingles were installed. Even the horizontal coursing matched because the exposure length for both old and new shingles was 

the same. Photo: Williamsport Preservation Training Center. 

thinness of the shingle, the durability of the wood species used, the exposure to the sun, the slope of the 

roof, the presence of lichens or moss growing on the 

shingle, poor ventilation levels under the shingle or in 

the r<?of, the presence of overhanging tree limbs, pollutants in the air, the original installation method, and 

the history of the roof maintenance. Erosion of the 

softer wood within the growth rings is caused by rainwater, wind, grit, fungus and the breakdown of cells 

by ultraviolet rays in sunlight. If the shingles cannot 

adequately dry between rains, if moss and lichens are 

allowed to grow, or if debris is not removed from the 

roof, moisture will be held in the wood and accelerate 

deterioration. Moisture trapped under the shingle, 

condensation, or poorly ventilated attics will also accelerate deterioration. 

In addition to the eventual deterioration of wooden 

shingles, impact from falling branches and workmen 

walking on the roof can cause localized damage. If, 

however, over 20% of the shingles on anyone surface 

appear eroded, cracked, cupped or split, or if there is 

evidence of pervasive moisture damage in the attic, 

replacement should be considered. If only a few shingles are missing or damaged, selective replacement 

may be possible. For limited replacement, the old shingle is removed and a new shingle can be inserted and 

held in place with a thin metal tab, or "babbie." This 

reduces disturbance to the sound shingles above. In 

instances where a few shingles have been cracked or 

the joint of overlapping shingles is aligned and thus 

forms a passage for water penetration, a metal flashing 

piece slipped under the shingle can stop moisture temporarily. If moisture is getting into the attic, repairs 

must be made quickly to prevent deterioration of the 

roof structural framing members. 

When damage is extensive, replacement of the shingles will be necessary, but the historic sheathing or 

shingle lath under the shingles may be in satisfactory 

condition. Often, the historic sheathing or shingle 

laths, by their size, placement, location of early nail 

holes, and water stain marks, can give important infor-
12. Inappropriately selected and installed wooden shingles can drastically 

alter the historic character of a building. This tavern historically was roofed 

with handsplit and dressed shingles of a relatively smooth appearance. In 

this case, a commercially available shake was used to effect a "rustic" appear- ance. Photo: National Park Service. 

mation regarding the early shingles used. Before specifying a replacement roof, it is important to establish the 

original shingle material, configuration, detailing and installation (see illus. 11). If the historic shingles are still in 

place, it is best to remove several to determine the size, 

shape, exposure length, and special features from the 

unweathered portions. If there are already replacement 

shingles on the roof, it may be necessary to verify 

through photographic or other research whether the 

shingles currently on the roof were an accurate replacement of the historic shingles. 

The following information is needed in order to develop accurate specifications for a replacement shingle: 

Original wood type (White Oak, Cypress, Eastern 

White Pine, Western, Red Cedar, etc.) 

Size of shingle (length, width, butt thickness, taper) 

Exposure length and nailing pattern (amount of exposure, placement and type of nails) 

Type of fabrication (sawn, handsplit, dressed, beveled, 

etc.) 

Distinctive details (hips, ridges, valleys, dormers, etc.) 

Decorative elements (trimmed butts, variety of pattern, 

applied color coatings, exposed nails) 

Type of substrate (open shingle lath or sheathing, 

closed sheathing, insulated attics, sleepers, etc.) 

Replacement roofs must comply with local codes 

which may require, for example, the use of shingles 

treated with chemicals or pressure-impregnated salts to 

retard fire. These requirements can usually be met 

without long-term visual effects on the appearance of 

the replacement roof. 

The accurate duplication of a wooden shingle roof 

will help ensure the preservation of the building's architectural integrity. Unfortunately, the choice of an 

inappropriate shingle or poor installation can severely 

detract from the building's historic appearance (see 

illus. 12). There are a number of commercially available 

wooden roofing products as well as custom roofers 

who can supply specially-made shingles for historic 

preservation projects (see Shingle and Shake Chart, 

illus. 13). Unless restoration or reconstruction is being 

undertaken, shingles that match the visual appearance 

of the historic roof without· replicating every aspect of 

the original shingles will n(!)rmally suffice. For example, 

if the historic wood species' is no longer readily available, Western Red Cedar or Eastern White Pine may be 

acceptable. Or, if the shingles are located high on a 

roof, sawn shingles or comwercially available shakes 

with the rustic faces factory-sawn off may adequately 

reproduce the appearance of an historic handsplit and 

dressed shingle. 

There will always be certa~n features, however, that 

are so critical to the building's character that they 

should be accurately reproduced. Following is guidance on matching the most important visual elements. 

Highest Priority in Replacement Shingles: 

• best quality wood with a similar surface texture 

• matching size and shape: thickness, width, length 

• matching installation pattern: exposure length, overlap, hips, ridges, valleys, etc. 

• matching decorative features: fancy butts, color, exposed nails 

Areas of Acceptable Differerices: 

• species of wood 

• method of fabrication of shingle, if visual appearance 

matches 

• use of fire-retardants, or preservative treatments, if 

visual impact is minimal 

• use of modern flashing, if sensitively installed 

• use of small sleepers for ventilation, if the visual 

impact is minimal and rake boards are sensitively 

treated 

• method of nailing, if the visual pattern matches 

Treatments and Materials to Avoid: 

• highly textured wood surfaces and irregular butt 

ends, unless documented 

• standardized details (prefab hips, ridges, panels, etc.) 

unless documented 

• too wide shingles or those with flat grain (which may 

curl), unless documented 

What is Currently Available 

Types of Wood: Western Red Cedar, Eastern White 

Pine, and White Oak are most readily available today. 

For custom orders, cypress, red oak, and a number of 

other historically used woods may still be available. 

Some experiments using non-traditional woods (such 

as yellow pine and hemlock) treated with preservative 

chemicals are being tested for the new construction 

market, but are generally too thick, curl too easily, or 

have too pronounced a grain for use on historic buildings. 

Method of manufacture: Commercially available modern shingles and shakes are for the most part machinemade. While commercially available shakes are 

promoted by the industry as handsplit, most are split 

by machine (this reduces the high cost of hand labor). 

True handsplit shingles, made the traditional way with 

a froe and mallet, are substantially more expensive, but 

are more authentic in appearance than the rough, 

highly textured machine-split shakes. An experienced 

shingler can control the thickness of the handsplit 

shingle and keep the shingle surface grain relatively 

7 
Custom 

split & 

dressed 

Tapersplit* 

Straightsplit 

Handsplit* 

resawn 

Tapersawn* 

Sawnstraight 

butt 

Sawnfancy 

butt 

Steam-bent 

AVAILABLE WOODEN SHINGLES AND SHAKES FOR RE-ROOFING 

TYPE SIZE DESCRIPTION 

v 

u 

V 

V 

Made to match historic 

shingles 

Typically: 

L=15", 18", 24" 

W=4" - 14" 

Butts vary 1/2" -3/4" 

Typically: 

L= 15",18" , 24" 

W -4"-14" 

Butts vary 

mediums = 3/8-3/4" 

heavies = 3/4-11/." 

Typically: 

L=15", 18", 24" 

W =4"-14" 

Butts vary 

mediums = 3/8-3/4" 

heavies = 3/4-11/ ." 

Typically: 

L=15", 18" , 24" 

W=4"-14" 

Butts vary 1/2" -3/4" 

Typically: 

L=16"-.40 «3/8") 

18"-.45 

24" - .50 (1/2") 

W = Varies by order 

Typically: 

L= 16"-.40 «3/8") 

18" - .45 

24"-.50 (1 /2") 

W = Varies by order 

Varies by order to match, 

"Thatch" roofs 

Handsplit the traditional way with 

froe & mallet. Tapered. Surfaces 

dressed for smoothness 

Commercially available. Handsplit 

the traditional way with froe & 

mallet. Tapered. Bundles contain 

varying widths & butt thicknesses. 

Surfaces may be irregular along 

grain. 

Commercially available. Hand or 

machine split without taper. 

Bundles contain varying butt 

thicknesses; often very wide 

shingles. Surface may be irregular 

along the grain. Thick shingles not 

historic. 

Commercially available. Machine 

split and sawn on the backs to 

taper. Split faces often irregular, 

even corrugated in appearance. 

Butt thickness vary and may be too 

wide. 

Commercially available. Made from 

split products with sawn surfaces. 

Tapered. Butt thicknesses vary and 

shingles may be too wide. Saw 

marks may be pronounced. 

Custom or commercially available. 

Tapered. Sawn by circular saw. 

Custom or ~ommercially available. 

Tapered. Sawn by circular saw. A 

variety of fancy butts available 

Custom or commercially available. 

Tapered. Thin sawn shingles are 

steamed and bent into rounded 

forms. 

NOTES 

Appropriate if: 

• Worked to match 

uniformly dressed 

original shingles 

Appropriate if: 

• irregular surfaces are 

dressed 

• butt thicknesses ordered 

uniform 

• wide shingles are split 

Not appropriate for most 

preservation projects 

• Limited use of thin, 

even straightsplits on 

some cabins, barns, etc. 

Not appropriate for 

preservation projects 

Appropriate if: 

• butt thicknesses ordered 

uniform 

• wide shingles are split 

• pronounced saw marks 

sanded 

Appropriate to reproduce 

historic sawn shingles 

Appropriate to reproduce 

historic fancy butts 

Appropriate to reproduce 

"thatch" shingles 

13. This chart identifies a variety of shingles and shakes used for reroofing buildings. The * identifies product names used by the Red Cedar Shingle and Handsplit 

Shake Bureau, although shingles and shakes of the types described are available in other woods. Manufacturers define "Shakes" as split products while "shingles" 

refer to sawn products. Shingle, however, is the historic term used to describe wooden roofing products, regardless of how they were made. Whether shingles or 

shakes are specified for re-roofing, they should match the size and appearance of the historic shingles. Chart: Sharon C. Park; delineation by Kaye Ellen Simonson. 

8 
even. To have an even roof installation, it is important 

to have handsplit shingles of uniform taper and to have 

less than 1/8th variation across the surface of the shingle. For that reason, it is important to dress the shingles or to specify uniform butt thickness, taper, and 

surfaces. Commercially available shakes are shipped 

with a range of butt sizes within a bundle (e.g., 1/2" , 

5/8", 3/4" as a mix) unless otherwise specified. Commercially available shakes with the irregular surfaces 

sawn off are also available . In many cases, except for 

the residual circular saw marks, these products appear 

not unlike a dressed handsplit shingle. 

Sawn shingles are still made much the same way as 

they were historically-using a circular saw. The circular saw marks are usually evident on the surface of 

most sawn shingles. There are a number of grooved, 

striated, or steamed shingles of the type used in the 

20th century to effect a rustic or thatched appearance. 

Custom sawn shingles with fancy butts or of a specified thickness are still available through mill shops. In 

fact, shingles can be fabricated to the weathered thickness in order to be integrated into an existing historic 

roof. If sawn shingles are being used as a substitute for 

dressed handsplit shingles, it may be desirable to belt 

sand the surface of the sawn shingles to reduce the 

prominence of the circular saw marks. 

As seen from the Shingle and Shake chart, few of the 

commercially available shakes can be used without 

some modification or careful specification. Some, such 

as heavy shakes with a corrugated face, should be 

avoided altogether. While length, width, and butt configuration can be specified, it is more difficult to ensure 

that the thickness and the texture will be correct. For 

that reason, whatever shingle or shake is desired, it is 

important to view samples, preferably an entire bundle, before specifying or ordering. If shingles are to be 

trimmed at the site for special conditions, such as 

fanned hips or swept valleys, additional shingles 

should be ordered. 

Coatings and Treatments: Shingles are treated to obtain 

a fire-retardant rating; to add a fungicide preservative 

(generally toxic); to revitalize the wood with a penetrating stain (oil as well as water-based); and to give color. 

While shingles can be left untreated, local codes may 

require that only fire-retardant shingles be used. In 

those circumstances, there are several methods of obtaining rated shingles (generally class "B" or "C"). The 

most effective and longest-lasting treatment is to have 

treated salts pressure-impregnated into the wood cells 

after the shingles have been cut. Another method 

(which must be periodically renewed) is to apply chemicals to the surface of the shingles. If treated shingles 

need trimming at the site, it is important to check with 

the manufacturer to ensure that the fire-retardant qualities will not be lost. Pressure-impregnated shingles, 

however, may usually be trimmed without loss of fireretardant properties. 

The life of a shingle roof can be drastically shortened 

if moss, lichens, fungi or bacterial spores grow on the 

wood. Fungicides (such as chromated copper arsenate, 

CCA) have been found to be effective in inhibiting 

such fungal growth, but most are toxic. Red cedar has 

a natural fungicide in the wood cells and unless the 

shingles are used in unusually warm, moist environments, or where certain strains of spores are found, an 

applied fungicide is usually not needed. For most 

woods, the Forest Products Laboratory of the U.S. Department of Agriculture has found that fungicides do 

extend the life of the shingles by inhibiting growth on 

or in the wood. There are a variety available. Care 

should be taken in applying these chemicals and meeting local code requirements for proper handling. 

Penetrating stains and water repellent sealers are 

sometimes recommended to revitalize wood shingles 

subject to damage by ultraviolet rays. Some treatments 

are oil-borne, some are water-borne, and some are 

combined with a fungicide or a water repellent. If any 

of these treatments is to be used, they should be identified as part of the specifications. Manufacturers should 

be consulted regarding the toxicity or other potential 

complications arising from the use of a product or of 

several in combination. It is also important not to coat 

the shingles with vapor-impermeable solutions that 

will trap moisture within the shingle and cause rotting 

from beneath. 

Specifications for the Replacement Roof 

Specifications and roofing details should be developed 

for each project. Standard specifications may be used 

as a basic format, but they should be modified to re-

£lect the conditions of each job. Custom shingles can 

still be ordered that accurately replicate a historic roof, 

and if the roof is simple, an experienced shingler could 

install it without complicated instructions. Most rehabilitation projects will involve competitive bidding, and 

each contractor should be given very specific information as to what type of shingles are required and what 

the installation details should be. For that reason, both 

written specifications and detailed drawings should be 

part of the construction documents. 

For particularly complex jobs, it may be appropriate 

to indicate that only roofing contractors with experience in historic preservation projects be considered (see 

illus. 14). By pre-qualifying the bidders, there is greater 

assurance that a proper job will be done. For smaller 

jobs, it is always recommended that the owner or architect find a roofing contractor who has recently completed a similar project and that the roofers are 

similarly experienced. 

Specifications identify exactly what is to be received 

from the supplier, including the wooden shingles, 

nails, £lashing, and applied coatings. The specifications 

also include instructions on removing the old roofing 

(sometimes two or more earlier roofs), and on preparing the surface for the new shingle3, such as repairing 

damage to the lath or sheathing boards. If there are to 

be modifications to a standard product, such as cutting 

beveled butts, planing off residual surface circular saw 

marks, or cbntrolling the mixture of acceptable widths 

(3" -8"), these too should be specified. Every instruction for modifying the shingles themselves should be 

written into the specifications or they may be overlooked. 

The specifications and drawn details should describe 

special features important to the roof. Swept valleys, 

combed ridges, or wedged dormer cheek run-offs 

should each be detailed not only with the patterning of 

the shingles, but also with the placement of £lashing or 

other unseen reinforcements. There are some modern 

products that appear to be useful. For example, paper9 
Replacement Roofing for Appomattox Manor: City 

Point Unit of Petersburg National Battlefield, Hopewell, Virginia 

A. The later non-historic shingles were removed from Appomattox ¥anor 

(circa 1840 with later additions) and roofing paper was installed for temporary protection during the re-shingling. 

B. These weathered historic 19th-century handsplit and dressed shingles 

were found in place under a later altered roof. Note the straight butt eave shingles under the curved butts of the historic dormer shingles. 

D. The fanned hips (seen here), swept valleys, and projecting ridge combs 

were installed as part of the re-roofing project. Special features, when documented, should be reproduced when re-shingling historic roofs. 

Excerpts from Specifications: 

Type of wood to be used: Western Red Cedar. 

Grade of wood and manufacturing process: Number 

One, Tapersplit Shakes, 100% clear, 100% edgegrain, 

100% heartwood, no excessive grain sweeps, curvatures 

not to exceed 1/2" from level plain in length of shake; 

off grade (7% tolerance) material must not be used. 

Size of the shingle: 18" long, 5/8" butt tapered to 1/4" 

head, 3" -4" wide, sawn curved butts, 5-1/2" exposure 

Surface finish and any applied coatings: relatively 

smooth natural grain, no more than 1/8" variation in 

surface texture, butt thickness to be uniform throughout bundles. Site dipped with fire-rated chemicals 

tinted with red iron oxide for opaque color. 

Type of nails and flashing: double hot dipped galvanized nails sized to penetrate sheathing totally; metal 

flashing to be 20 oz. lead-coated copper, or ternecoated stainless steel; additional flashing reinforcement 

to be aluminum foil type with fiber backing to use at 

hips, ridges, eaves, and valleys. 

Type of sheathing: uninsulated attic, any deteriorated 

3/4" sheathing boards, spaced 1/2" -3/4", to be replaced 

in kind. 

C. The replacement shingles (see specifications above), matched the historic 

shingles and were of such high quality that little hand dressing was needed 

at the site. The building paper, a temporary protection, was removed as the 

shingles were installed on the sheathing boards. 

III 

III 

"'------.. 

E. In order to achieve a "Class B" fire-rating, the shingles were dipped in 

fire-retardant chemicals and allowed to dry prior to installation. Iron oxide 

was added to this chemical dip to stain the shingles to match the historic red 

color. These coatings will need periodic reapplication. 

14. Original 19th-century handsplit and dressed wooden shingles 18" long, 3" -4" wide, and 518" thick were found in place on the Appomattox Manor at Hopewell, 

Virginia. The butts were curved and evidence of a red stain remained. The specifications and details were researched so that the appearance of the historic shingles 

and installation patterns could be matched in the re-shingling project. Photos: John Ingle. 

10 
coated and reinforced metal-laminated flashing is easy 

to use and, in combination with other flashing, gives 

added protection over eaves and other vulnerab~e ~­

eas; adhesives give a stronger attachment at proJectmg 

roofing combs that could blow away in heavy wind 

storms. Clear or light-colored sealants may be less obvious than dark mastic often used in conjunction with 

flashing or repairs. These modern treatments should 

not be overlooked if they can prolong the life of the 

roof without changing its appearance . 

Roofing Practices to Avoid 

Certain common roofing practices for modern installations should be avoided in re-roofing a historic building 

unless specifically approved in advance by the arc.hitecto These practices interfere with the proper drymg of 

the shingles or result in a sloppy installation that will 

accelerate deterioration (see illus. 15). They include 

improper coverage and spacing of shingles, use of staples to hold shingles, inadequate ventilation, particularly for heavily insulated attics, use of heavy building 

felts as an underlayment, improper application of surface coatings causing stress in the wood surfaces, and 

use of inferior flashing that will fail while the shingles 

are still in good condition. 

Avoid skimpy shingle coverage and heavy building 

papers. It has become a common modern practice to 

lay impregnated roofing felts under new wooden shingle roofs. The practice is especially prevalent in roofs 

that do not achieve a full triple layering of shingles. 

Historically, approximately one third of each single was 

exposed, thus making a three-ply or three-layered roof. 

This assured adequate coverage. Due to the expense of 

wooden shingles today, some roofers expose more of 

the shingle if the pitch of the roof allows, and compensate for less than three layers of shingles by using 

building felts interwoven at the top of each row of shingles. This absorptive material can hold moisture on the 

underside of the shingles and accelerate deterioration. 

If a shingle roof has proper coverage and proper flashing, such felts are unnecessary as a general rule. 

15. These commercially available roofing products with rustic split faces are 

not appropriate for historic preservation projects. In addition to the inaccurate appearance, the irregular surfaces and often wide spaces between shingles will allow wind-driven moisture to penetrate up and under them. The 

excessively wide boards will tend to cup, curl and crack. Moss, lichens and 

debris will have a tendency to collect on these irregular surfaces, further 

deteriorating the roofing. Photo: Sharon C. Park. 

However, the selective use of such felts or other reinforcements at ridges, hips and valleys does appear to 

be beneficial. 

Beware of heavily insulated attic rafters. Historically, 

the longest lasting shingle roofs were generally the 

ones with the best roof ventilation. Roofs with shingling set directly on solid sheathing and where there is 

insulation packed tightly between the wooden rafters . 

without adequate ventilation run the risk of condensatIonrelated moisture damage to wooden roofing components. This is particularly true for air-conditioned 

structures. For that reason, if insulation must be used, 

it is best to provide ventilation channels between the 

rafters and the roof decking, to avoid heavy felt building papers, to consider the use of vapor barriers, and 

perhaps to raise the shingles sligh~ly by using "sle~pers" over the roof deck. This practice was popular m 

the 1920s in what the industry called a "Hollywood" 

installation, and examples of roofs lasting 60 years are 

partly due to this under-shingle ventilation (refer to 

illus. 9). 

Avoid staples and inferior flashing. The common 

practice of using pneumatic staple guns to affix s~ingles can result in shooting staples through the shmgles, in crushing the wood fibers, or in cracking the 

shingle. Instead, corrosion-resistant nails, generally 

with barked or deformed shanks long enough to extend about 3/4" into the roof decking, should be specified. Many good roofers have found that the pneumatic 

nail guns, fitted with the proper nails and set at the 

correct pressure with the nails just at the shingle surface have worked well and reduced the stress on shingles' from missed hammer blows. If red cedar is used, 

copper nails should not be specified because a c~emical reaction between the wood and the copper will 

reduce the life of the roof. Hot-dipped, zinc-coated, 

aluminum, or stainless steel nails should be used. In 

addition, copper flashing and gutters generally should 

not be used with red cedar shingles as staining will 

occur, although there are some historic examples where 

very heavy gauge copper was used which outlasted the 

roof shingles. Heavier weight flashing (20 oz.) holds up 

better than lighter flashing, which may deteriorate. 

faster than the shingles. Some metals may react wlth 

salts or chemicals used to treat the shingles. This 

should be kept in mind when writing specifications. 

Terne-coated stainless steel and lead-coated copper are 

generally the top of the line if copper is not appr<;>priate. 

Avoid patching deteriorated roof lath or sheathmg 

with plywood or composite materials. Full size lumber 

may have to be custom-ordered to match the size and 

configuration of the original sheathing in order to provide an even surface for the new shingles. It is best to 

avoid plywood or other modern composition boards 

that may deteriorate or delaminate in the future ~. there 

is undetected moisture or leakage. If large quantities of 

shingle lath or sheathing must be removed and replaced, the work should be done in sections to avoid 

possible shifting or collapse of the roof structure. 

Avoid spray painting raw shingles on a roof after 

installatiQn. Rapidly drying solvent in the paint will 

tend to warp the exposed surface of the shingles. Instead, it is best to dip new shingles prior to installation 

to keep all of the wood fibers in the same tension. 

Once the entire shingle has been treated, however, 

later coats can be limited to the exposed surface. 

11 
Maintenance 

The purpose of regular or routine maintenance is to 

extend the life of the roof. The roof must be kept clean 

and inspected for damage both to the shingles and to 

the flashing, sheathing, and gutters. If the roof is to be 

walked on, rubber soled shoes should be worn. If there 

is a simple ridge, a ladder can be hooked over the roof 

ridge to support and distribute the weight of the 

inspector. 

Keeping the roof free of debris is important. This 

may involve only sweeping off pine needles, leaves 

and branches as needed. It may involve trimming overhanging branches. Other aspects of maintenance, such 

as removal of moss and lichen build-up, are more difficult. While they may impart a certain charm to roofs, 

these moisture-trapping organisms will rot the shingles 

and shorten the life of the roof. Buildups may need 

scraping and the residue removed with diluted bleaching solutions (chlorine), although caution should be 

used for surrounding materials and plants. Some roofers recommend power washing the roofs periodically 

to remove the dead wood cells and accumulated debris. 

While this makes the roof look relatively new, it can 

put a lot of water under shingles, and the high pressure may crack or otherwise damage them. The added 

water may also leach out applied coatings. 

If the roof has been treated with a fungicide, stain, or 

revitalizing oil, it will need to be re-coated every few 

years (usually every 4-5). The manufacturer should be 

consulted as to the effective life of the coating. With the 

expense associated with installation of wood shingles, 

it is best to extend the life of the roof as long as possible. One practical method is to order enough shingles 

in the beginning to use for periodic repairs. 

Periodic maintenance inspections of the roof may 

reveal loose or damaged shingles that can be selectively 

replaced before serious moisture damage occurs (see 

illus. 16). Keeping the wooden shingles in good condition and repairing the roof, flashing and guttering, as 

needed, can add years of life to the roof. 

16. Routine maintenance is necessary to extend the life of the roof. On this 

roof, the shingles have not seriously eroded, but the presence of lichens and 

moss is becoming evident and there are a few cracked and missing shingles. 

The moss spores should be removed, missing shingles replaced, and small 

pieces of metal flashing slipped under cracked shingles to keep moisture from 

penetrating. Photo: Williamsport Preservation Training Center. 

Cover Photo: 1907 view of a young couple's first home in a cedar 

stump with a shingled roof. Photo: Historical Society of Seattle and 

King County, Washington. 

Conclusion 

A combination of careful research to determine the 

historic appearance of the roof, good specifications, 

and installation details designed to match the historic 

roof, and long-term maintenance, will make it possible 

to have not only a historically authentic roof, but a 

cost-effective one. It is important that professionals be 

part of the team from the beginning. A preservation 

architect should specify materials and construction 

techniques that will best preserve the roof's historic 

appearance. The shingle supplier must ensure that the 

best product is delivered and must stand behind the 

guarantee if the shipment is not correct. The roofer 

must be knowledgeable about traditional craft practices. Once the new shingle roof is in place, it must be 

properly maintained to give years of service. 

Acknowledgements 

The author gratefully acknowledges the invaluable assistance of 

co-worker Michael Auer in preparing this brief for publication. In 

addition, the following individuals are to be thanked for their contribution to this manuscript: Reed Engle, Historical Architect, NPS; 

John Ingle, Historical Architect, NPS; Martin Obando, Eastern District Manager, Red Cedar Shingle & Handsplit Shake Bureau; and 

Peter Sandbeck, North Carolina Division of Archives and History. 

Appreciation is extended to: the staff of Technical Preservation Services Branch and NPS regional offices; Michael Lynch of the Office of 

Parks, Recreation and Historic Preservation in Albany, New York; and 

to Penelope H . Batcheler and William Brookover, Historical Architects, Independence National Historic Park, for their review of this 

manuscript and constructive comments. Special thanks are given to 

Kaye Ellen Simonson for the illustrations in the charts. 

This publication has been prepared pursuant to the National Historic Preservation Act of 1966, as amended. Preservation Brief 19 was 

developed under the technical editorship of Lee H. Nelson, FAIA, 

Chief, Preservation Assistance Division, National Park Service, U.S. 

Department of the Interior, P.O. Box 37127, Washington, D.C. 20013-

7127. Comments on the usefulness of this information are welcomed 

and may be sent to Mr. Nelson at the above address. This publication 

is not copyrighted and can be reproduced without penalty. Normal 

procedures for credit to the author and the National Park Service are 

appreciated. 

Further Reading 

Bucher, Robert C. "The Long Shingle." Pennsylvania Folklife, Vol. 

XVill, No. 4, Summer 1969. 

Cox, Richard E. "Wooden Shingles from the Fortress of Louisbourg." 

Bulletin of the Association for Preservation Technology, Vol. II, Nos. 1-2 

1970 p.p. 65. 

Engle, Reed. "Restoring a Roofing." CRM Bulletin, a publication of 

the National Park Service, Vol. 8, No. 6 Dec. 1985. 

Kidder, EE. Building Construction and Superintendence, Part II. New 

York: William T. Comstock, 1902. 

LeVan, Susan. "Fire-Retardant Treatments for Wood Shingles." 

Techline, Madison, Wisconsin: U.S.D.A. Forest Service, 1988. 

Niemiec, 5 .5. and T.D. Brown. "Care and Maintenance of Wood Shingle 

and Shake Roofs. " Oregon State University Extension Service, September 1988. Publication #EC 1271. 

The Old House Journal, Vol. Xl, No. 3, April 1983. Special Roof Issue. 

Peterson, Charles E. (editor). Building Early America. Radnor, Pennsylvania: Chilton Book Co. 1976. 

Stevens, John. "Shingles." Bulletin of the Association for Preservation 

Technology, Vol. II, Nos. 1-2 1970, pp. 74. 

Sweetser, Sarah M. Preservation Briefs 4: Roofing for Historic Buildings. 

Washington, D.C.: Technical Preservation Services Division, National 

Park Service, U.S. Department of the Interior, 1978. 

Tollesten, Kristin. "Shingles and Shingled Roofs." No Future Without 

the Past. Rome, Italy: ICOMOS, 1981. pp. 347-360.