PRESERVATION 

BRIEFS 

Aluminum and Vinyl Siding on 

Historic Buildings 

The Appropriateness of Substitute Materials 

for Resurfacing Historic Wood Frame 

Buildings. 

John H. Myers, revised by Gary L. Hume 

• @

'l::t, u.s:Departmentof.theInteriOr ~""'":: _~ National Park Service 

. . i,.:': Cultural Resources 

. Heritage Preservation Services 

Standard 6 of the Secretary of the Interior's "Standards for Rehabilitation" states that "deteriorated architectural features shall be repaired 

rather than replaced, wherever possible . In the event replacement is necessary , the new material should match the material being replaced in 

composition, design, color, texture, and other visual qualities. " Therefore, the Secretary's Standards and their accompanying Guidelines never 

recommend resurfacing frame buildings with any new material that does not duplicate the historic material because of the strong potential of 

altering the character of the historic building. 

A historic building is a product of the cultural heritage of 

its region, the technology of its period, the skill of its 

builders, and the materials used for its construction. To 

assist owners, developers and managers of historic property in planning and completing rehabilitation project work 

that will meet the Secretary's "Standards for Rehabilitation"{36 CFR 67), the following planning process has been 

developed by the National Park Service and is applicable 

to all historic buildings. This planning process is a sequential approach to the preservation of historic wood frame 

buildings. It begins with the premise that historic materials should be retained wherever possible. When retention, including retention with some repair, is not possible, then replacement of the irreparable historic material 

can be considered. The purpose of this approach is to 

determine the appropriate level of treatment for the preservation of historic wood frame buildings. The planning 

process has the following four steps: 

1. Identify and preserve those materials and features 

that are important in defining the building's historic 

character. This may include features such as wood siding, 

brackets, cornices, window architraves, doorway pediments, 

and their finishes and colors. 

2. Undertake routine maintenance on historic materials 

and features. Routine maintenance generally involves the 

least amount of work needed to preserve the materials 

and features of the building. For example, maintenance of 

a frame building would include caulking and painting; or, 

where paint is extensively cracking and peeling, its removal and the re-application of a protective paint coating. 

3. Repair historic materials and features. For a historic 

material such as wood siding, repair would generally involve patching and piecing-in with new material according 

to recognized preservation methods. 

Photo , Hugh C. Miller 

Photo, John H. Myers 

Historic wood sidings exhibit rich and varied surface textures. 

They range from hand-split clapboards of short lengths with 

feather-edged ends, to pit or mill sawn boards which can be 

beveled, rabbeted, milled, or beaded. 
Pho to: Laurie Robin Hammel 

When a building is in need of maintenance, such as the house on the right which needs painting, some owners consider installing 

aluminum or vinyl siding. The result, like the house on the left, can be a complete loss of architectural character due to the covering of details (cornice), the removal of features (window trim), and a change of scale due to inappropriate siding dimensions. 

4. Replace severely damaged or deteriorated historic 

materials and features in kind. Replacing sound or repairable historic material is never recommended; however, 

if the historic material cannot be repaired because of the 

extent of deterioration or damage, then it will be necessary to replace an entire character-defining feature such as 

the building's siding. The preferred treatment is always 

replacement in kind, that is, with the same material. Because this approach is not always feasible, provision is 

made under the recommended treatment options in the 

Guidelines that accompany the Secretary of the Interior's 

Standards to consider the use of a compatible substitute 

material. A substitute material should only be considered, 

however, if the form, detailing, and overall appearance of 

the substitute material conveys the visual appearance of 

the historic material, and the application of the substitute 

material does not damage, destroy or obscure historic 

features. 

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In many cases, the replacement of wood siding on a historic building is proposed because little attention has been 

given to the retention of historic materials. Instead, the 

decision to use a substitute material is made because: (1) it 

is assumed that aluminum or vinyl siding will be a maintenance-free material; and (2) there is the desire to give a 

building a "remodeled" or "renovated" appearance. A 

decision to replace historic material must, however, be 

carefully considered ror its impact on the historic resource-even when the model planning process has been 

followed and the appropriate treatment is replacement. 

Therefore, this brief focuses on the visual and physical 

consequences of using a substitute material such as aluminum or vinyl siding for new siding installations on a 

wood frame historic building. These concerns include the 

potential of damaging or destroying historic material and 

features; the potential of obscuring historic material and 

features; and, most important, the potential of diminishing the historic character of the building. 
Photo: Technical Preservation Services 

Aluminum and vinyl siding are available in a variety of widths 

and colors, but the optional wood graining is not characteristic 

of real wood siding. 

The Historic Character of Buildings and Districts 

The character or "identity" of a historic building is established by its form, size, scale and decorative features. It is 

also influenced by the choice of materials for the wallsby the dimension, detailing, color, and other surface characteristics. This is particularly true for wood frame buildings which are the typical objects of aluminum or vinyl 

siding applications. Since wood has always been present 

in abundance in America, it has been a dominant building 

material in most parts of the country. Early craftsmen 

used wood for almost every aspect of building construction: for structural members such as posts, beams and 

rafters, and for cladding materials and decorative details, 

such as trim, shakes, and siding. 

The variety of tools used, coupled with regional differences in design and craftsmanship, has resulted in a richness and diversity of wood sidings in America. For example, narrow boards with beveled, lapped joints called 

"clapboards" were used on New England frame dwellings. 

The size and shape of the "clapboards" were determined 

by the process of hand splitting or "riving" bolts of wood. 

The width, the short lengths, the beveled lapping, the 

"feathered" horizontal joints, and the surface nailing of 

the clapboards created a distinctive surface pattern that is 

recognizable as an important part of the historic character 

of these structures. 

The sawn and hand-planed clapboards used throughout 

the Mid-Atlantic and Southern states in the eighteenth and 

early nineteenth centuries, by contrast, have a wide exposure-generally between six and eight inches. The exposure of the siding, frequently coupled with a beaded 

edge, created a very different play of light and shadow on 

the wall surface, thus resulting in a different character. 

The "German" or "Novelty siding" -a milled siding that is 

thin above and thicker below with a concave bevel-was 

used throughout many parts of the United States in the 

late nineteenth and early twentieth century but with regional variations in materiaL profile, and dimensions. 

One variation of this type of milled siding was called 

"California siding" and was milled with a rabbetted or 

shiplap edge to insure a tight installation of the weatherboards. Shingles were also commonly used as an exterior 

cladding materiaL and in buildings such as the Bungalow 

style houses, were often an important character-defining 

feature of the exterior. Shingles were often applied in 

decorative patterns by varying the lap, thus creating alternating rows of narrow exposures and wide exposures. 

Shingles were also cut in geometric patterns such as diamond shapes and applied in patterns. This treatment was 

commonly used in the gable end of shingled houses. Siding and wood shingles were often used in combination 

with materials such as cobblestone and brick in Bungalow 

style buildings to create a distinctive interplay of surfaces and materials. 

The primary concern, therefore, in considering replacement siding on a historic building, is the potential loss of 

those features such as the beaded edge, "drop" profile, 

and the patterns of application. Replacing historic wood 

siding with new wood, or aluminum or vinyl siding could 

severely diminish the unique aspects of historic materials 

Photo, Nancy]. Long 

Two originally similar houses. When aluminum was installed on the house on the right, the barge boards, scrollwork, columns, 

and railings were removed. The distinctive shingled gable and attic vent were covered, further compromising the building's architectural integrity. 

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Photo, John H. Myers 

This brick rowhouse was covered with vertical and horizontal 

aluminum siding. Such treatment is inappropriate for historic 

masonry buildings. 

and craftsmanship. The inappropriate use of substitute 

siding is especially dramatic where sufficient care is not 

taken by the owner or applicator and the width of the 

clapboards is altered, shadow reveals are reduced, and 

molding or trim is changed or removed at the corners, at 

cornices or around windows and doors. Because substitute 

siding is usually added on top of existing siding, details 

around windows and doors may appear set back from the 

siding rather than slightly projecting; and if the relationship of molding or trim to the wall is changed, it can 

result in the covering or removal of these historic features. 

New substitute siding with embossed wood graining-intended to simulate the texture of wood-is also visually 

inappropriate. Exaggerated graining would have been undesirable on real wood siding and is generally found only 

after sandblasting, a destructive and totally unacceptable 

treatment for wood. 

While this discussion focuses primarily on the historic 

character of individual wood frame buildings, of equal 

importance is the context of buildings that comprise a 

historic district or neighborhood. Changes to the character-defining features of a building, such as distinctive 

clapboarding and other wall surfaces and decorative trim, 

always have an impact on more than just that building; 

they also alter the historic visual relationship between the 

buildings in the district. If character-defining weather4 

boards, clapboards or shingles are replaced on a number 

of buildings in a historic district, the historic character of 

the entire district may be seriously damaged. Because of 

the potential impact some substitute materials have on the 

character of a neighborhood or district, many communities regulate their use through zoning ordinances and 

design review boards. These ordinances and review 

boards usually require review and approval of proposed 

alterations to a historic building that could potentially impact the historic character of the building or the district, 

including the application of substitute materials, such as 

aluminum or vinyl siding. 

Preservation of a building or district and its historic 

character is based on the assumption that the retention of 

historic materials and features and their craftsmanship are 

of primary importance. Therefore, the underlying issue in 

any discussion of replacement materials is whether or not 

the integrity of historic materials and craftsmanship has 

been lost. Structures are historic because the materials and 

craftsmanship reflected in their construction are tangible 

and irreplaceable evidence of our cultural heritage. To the 

degree that substitute materials destroy and/ or conceal the 

historic fabric, they will always subtract from the basic 

integrity of historically and architecturally significant 

buildings. 

The Products and Their Installation 

The use of aluminum and vinyl siding really involves 

two separate industries. The siding materials themselves, 

including a variety of inside and outside corner pieces, 

trim and molding pieces and panning for window and 

door frames, are produced by a comparatively small number of manufacturers. The product information, advertising, and any manufacturer's warranties on the product 

itself are handled by this part of the industry. The installation of aluminum or vinyl siding is generally carried 

out by independent contractors or applicators, who are 

frequently called "home improvement" contractors, and 

they are not affiliated with the manufacturers. The manufacturer's warranties normally do not cover the installation, or any damage or defect resulting from the installation process. 

Since the manufacturer has little control over the quality of the installation, both the quality of the work and the 

sensitivity of the application are variable. This variation 

in quality has traditionally been a problem in the industry 

and one which the industry and its professional associations have attempted to correct through publishing and disseminating information on the proper application of vinyl 

and aluminum siding. 

Although it is sometimes argued that an artificial siding 

application is reversible since it can be removed, there is 

frequently irreversible damage to historic building materials if decorative features or trim are permitted to be cut 

down or destroyed, or removed by applicators and discarded. The installation process requires that the existing 

surface be flat and free of "obstructions" so that the new 

siding will be smooth and even in appearance. To achieve 

the requisite flat surface, furring strips are usually placed 

over the wall surface (vertical furring strips for horizontal 

aluminum or vinyl siding and vice-versa for vertical siding). The potential danger in this type of surface prepara-
tion is that the furring strips may change the relationship 

between the plane of the wall and the projecting elements 

such as windows, door trim, the cornice, or any other projecting trim or molding. Projecting details may also cause 

a problem. To retain them, additional cutting and fitting 

will usually be required. Further, additional or special 

molding pieces, or "accessories" as they are called by the 

industry, such as channels, inserts and drip caps, will be 

needed to fit the siding around the architectural fea tures. 

This custom fitting of the siding will be more laborintensive, adding to the cost of the siding installation. 

The existing wall fabric is further damaged by the nailing necessary to apply siding. Either by nailing directly to 

the building fabric or by nailing the furring strips to the 

old siding, the installation of aluminum or vinyl siding 

will leave numerous holes in wood siding, molding, trim, 

window and door frames. When applied to brick or other 

masonry units, the nail penetrations attaching the furring 

strips and siding can cause irreversible cracking or spalling 

of the masonry. Although this reference to damaging masonry is included as a point of fact, the application of 

aluminum or vinyl siding is highly inappropriate to historic masonry buildings. 

The Use of Aluminum or Vinyl Siding on 

Historic Buildings 

The maintenance and periodic painting of wood frame 

structures is a time-consuming effort and often a substantial expense for the homeowner. It is therefore understandable that a product which promises relief from periodic painting and gives the building a new exterior cladding would have considerable appeal. For these reasons, 

aluminum and vinyl siding have been used extensively in 

upgrading and rehabilitating the nation's stock of wood 

frame residential buildings. For historic residential 

buildings, aluminum or vinyl siding may be an acceptable 

alternative only if (1) the existing siding is so deteriorated 

or damaged that it cannot be repaired; (2) the substitute 

material can be installed without irreversibly damaging or 

obscuring the architectural features and trim of the building; and (3) the substitute material can match the historic 

material in size, profile and finish so that there is no 

change in the character of the historic building. In cases 

where a non-historic artificial siding has been applied to a 

building, the removal of such a siding, and the application 

of aluminum or vinyl siding would, in most cases, be an 

acceptable alternative, as long as the above-mentioned 

first two conditions are met. 

There are, however, also certain disadvantages in the 

use of a substitute material such as aluminum or vinyl 

siding, and these factors should be carefully considered 

before a decision is made to use such a material rather 

than the preferred replacement with new wood siding 

duplicating the old. 

Applying Siding without Dealing with Existing Problems 

Since aluminum and vinyl sidings are typically marketed 

as home improvement items, they are frequently applied 

to buildings in need of maintenance and repair. This can 

result in concealing problems which are the early warning 

signs of deterioration. Minor uncorrected problems can 

progress to the point where expensive, major repairs to 

the structure become necessary. 

If there is a hidden source of water entry within the 

wall or leakage from the roof, the installation of any new 

siding will not solve problems of deterioration and rotting 

that are occurring within the wall. If deferred maintenance 

has allowed water to enter the wall through deteriorated 

gutters and downspouts, for example, the cosmetic surface 

application of siding will not arrest these problems. In 

fact, if the gutters and downspouts are not repaired, such 

problems may become exaggerated because water may be 

channeled behind the siding. In addition to drastically 

reducing the efficiency of most types of wall insulation, 

such excessive moisture levels within the wall can contribute to problems with interior finishes such as paints or 

wallpaper, causing peeling, blistering or staining of the 

finishes. 

It cannot be overemphasized that a cosmetic treatment 

to hide difficulties such as peeling paint, stains or other 

indications of deterioration is not a sound preservation 

practice; it is no substitute for proper care and maintenance. Aluminum and vinyl siding are not directly at 

fault in these situations since property owners should 

determine the nature and source of their problems, then 

make appropriate repairs. The difficulty arises when 

owners perceive the siding as the total solution to their 

required maintenance and forgo other remedial action. 

Durability and Cost 

The questions of durability and relative costs of aluminum 

or vinyl siding compared to the maintenance cost of historic materials are complex. It is important to consider 

these questions carefully because both types of siding are 

marketed as long lasting, low maintenance materials. Assuming that the substitute sidings are not damaged, and 

that they will weather and age normally, there will be inevitable changes in color and gloss as time passes. A normal application of aluminum or vinyl siding is likely to 

cost from two to three times as much as a good paint job 

on wood siding. A sensitive application, retaining existing 

trim, will cost more. Therefore, to break even on expense, 

the new siding should last as long as two or three paintings before requiring maintenance. On wood two coats of 

good quality paint on a properly prepared surface can last 

from 8 to 10 years, according to the U.S. Department of 

Agriculture. If a conservative life of seven years is assumed for paint on wood, then aluminum and vinyl siding should last 15 to 21 years before requiring additional maintenance, to break even with the maintenance cost 

for painting wood siding. Once painted, the aluminum 

and vinyl siding will require repainting with the same frequency as wood. 

While aluminum siding can dent upon impact and the 

impact resistance of vinyl siding decreases in low temperatures and, therefore, is susceptible to cracking from 

sharp impact, these materials are generally not more 

vulnerable than wood siding and shingles. All siding 

materials are subject to damage from storm, fire, and vandalism; however, there is a major difference in the 

repairability of wood siding versus substitute materials 

such as aluminum and vinyl. Although they can all be 

repaired, it is much easier to repair wood siding and the 

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repair, after painting, is generally imperceptible. In addition, a major problem in the repairability of aluminum 

and vinyl siding, as mentioned above, is matching color 

since the factory finishes change with time. Matching the 

paint for wood siding has a greater likelihood of success. 

Energy 

Because of high fuel costs, there is a concern for energy 

conservation in historic materials as well as in substitute 

materials. Because aluminum and vinyl siding can be produced with an insulating backing, these products are 

sometimes marketed as improving the thermal envelope of 

a historic building. The aluminum and vinyl material 

themselves are not good insulators, and the thickness of 

any insulating backing would, of necessity, be too small 

to add to the energy efficiency of a historic building. 

What energy savings did accrue as a result of a siding application would probably be as much the result of the 

creation of an air space between the old and new siding as 

the addition of insulating material. If the historic wood 

siding were removed in the course of installing the aluminum or vinyl siding (even with an insulating backing), 

the net result would likely be a loss in overall thermal efficiency for the exterior sheathing. 

Preservation Briefs Number 3, "Conserving Energy in 

Historic Buildings," notes that the primary sources of 

energy loss in small frame buildings are the doors, windows and roof. It is, therefore, more cost-effective to apply storm windows, weatherstripping and attic insulation 

than to treat the sidewalls of these structures. There are 

numerous publications on energy retrofitting which explain techniques of determining cost-effectiveness based on 

utility costs, R-factors or materials and initial cost of the 

treatment. Persons interested in this approach may wish 

to read "Retrofitting Existing Houses for Energy Conservation: An Economic Analysis" published by the National 

Bureau of Standards, or the U.S. Department of Housing 

and Urban Development booklet "In the Bank or Up the 

Chimney." One such study in Providence, Rhode Island, 

determined that for a two-story house, twenty-five feet 

square, the payback period for twenty-three storm windows, two storm doors and six inches of attic insulation 

(R-20) was 4.4 years while the payback period of aluminum siding with an R-factor of 2.5 was 29.96 years. 

Most of the information which is available supports the 

position that aluminum or vinyl siding will not have a 

reasonable payback on an energy-saving basis alone. 

Summary 

The intent of this brief has been to delineate issues that 

should be considered when contemplating the use of aluminum or vinyl sidings on historic buildings and assessing 

under what circumstances substitute materials such as artificial siding may be used without damaging the integrity 

of the historic building or adversely changing its historic 

character. Many property owners are faced with decisions\ 

weighing the historic value of their building and its maintenance cost against the possible benefit of aluminum and 

vinyl siding materials. To assist in making these decisions, 

"The Secretary of the Interior's Standards for Rehabilitation and Guidelines for Rehabilitating Historic Buildings" 

6 

have been published and are available from National Park 

Service Regional Offices and State Historic Preservation 

Offices. Further, since rehabilitation projects for incomeproducing historic buildings often seek tax beneftis under 

the 1981 Economic Recovery Tax Act, as amended, it is 

essential that all work, such as the replacement of exterior 

siding, be carried out in conformance with the Standards 

and be consistent with the building's historic character to 

insure that the tax benefits are not denied. 

As stated earlier, the application of aluminum and vinyl 

siding is frequently considered as an alternative to the 

maintenance of the original historic material. The implication is that the new material is an economical and longlasting alternative and therefore somehow superior to the 

historic material. In reality, historic building materials 

such as wood, brick and stone, when properly maintained, 

are generally durable and serviceable materials. Their 

widespread existence on tens of thousands of old buildings 

after many decades in serviceable condition is proof that 

they are the original economic and long-lasting alternatives. All materials, including aluminum and vinyl siding 

can fall into disrepair if abused or neglected; however, the 

maintenance, repair and retention of historic materials are 

always the most architecturally appropriate and usually 

the most economically sound measures when the objective 

is to preserve the unique qualities of historic buildings. 

The appropriate preservation decision on the use of a 

substitute material in the rehabilitation of a historic 

building must always center on two principal concerns: 

the possible damage or destruction of historic building 

materials; and, the possible negative impact on the historic character of the building and the historic district 

or setting in which the building is located. Because applications of substitute materials such as aluminum and 

vinyl siding can either destroy or conceal historic building material and features and, in consequence, result in 

the loss of a building'S historic character, they are not 

recommended by the National Park Service. Such destruction or concealment of historic materials and features confuses the public perception of that which is truly historic 

and that which is imitative. 
Reading List 

"Condensation Problems in Your House: Prevention and Solution. " 

Information Bulletin No . 373. Washington, D.C. : U.S. Department of Agriculture, 1974. . 

Kiefer, Matthew J. "Vinyl and Aluminum Siding: Pro and Con. " Report 

to the Ashmont Hill Study Committee. Boston, Massachusetts: 

The Boston Landmarks Commission, 1977. 

"Landmark and Historic District Commission. " Vol. 4. No.5. 

Washington, D .C.: National Trust for Historic Preservation. October 1978. 

"Moisture Conditions in Walls and Ceilings of a Simulated Older Home 

in Winter. " Madison, Wisconsin: Forest Products LaboratoryUSDA, 1977. 

"Performance Criteria for Exterior Wall Systems." Washington, D.C. : 

National Bureau of Standards, 1974. 

"Rehab Right. " Oakland, California : City of Oakland Planning 

Department, 1978. 

Skoda, Leopold F. "Performance of Residential Siding Materials. " 

Washington, D.C.: National Bureau of Standards, 1972. 

Wood Handbook: Wood as an Engineering Material. Washington, D.C.: 

Forest Products Laboratory. U.S. Department of Agriculture, 

1974. 

This Preservation Brief was written by John H. Myers, Historical Architect, formerly with Technical Preservation Services, and was published first in 1979. The Brief was substantially revised in 1984 by Gary 

L. Hume, Deputy Division Chief, Preservation Assistance Division. H . 

Ward Jandl, Chief, Technical Preservation Services Branch, and the 

following Branch staff members are to be thanked for reviewing the 

manuscript and making suggestions that were incorporated into the final 

text: Emogene A. Bevitt, Kay Davidson Weeks, and Susan Dynes. 

This publication has been prepared pursuant to the Economic 

Recovery Tax Act of 1981 which directs the Secretary of the Interior to 

certify rehabilitations of historic buildings that are consistent with their 

historic character; the advice and guidance provided in this Brief will 

assist property owners in complying with the requirements of this law. 

Preservation Briefs 8 has been developed under the technical editorship 

of Lee H. Nelson, AlA, Chief, Preservation Assistance Division, National Park Service, U.S. Department of the Interior, Washington, D.C. 

20240. Comments on the usefulness of this information are welcomed 

and can be sent to Mr. Nelson at the above address. 

The drawing "A Tribute to Vinyl Siding. (Igloo)" on the front cover is 

reproduced from David Macaulay's "Great Moments in Architecture." 

Copyright © 1978 by David Macaulay and reprinted permission of 

Houghton Mifflin Company. 

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