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Aluminum and Vinyl Siding on Historic
Buildings
John H. Myers, revised by
Gary L. Hume
Standard 6 of the Secretary of the Interior's
Standards for Rehabilitation states that "deteriorated architectural
features shall be repaired rather than replaced. Where the severity of
deterioration requires replacement of a distinctive feature, the new feature
shall match the old in design, color, texture, and other visual qualities
and, where possible, materials..." The Guidelines further caution against
"removing or radically changing wood features which are important in defining
the overall historic character of the building so that, as a result, the
character is diminished."
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 steps:
- 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.
- 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 reapplication of a protective paint coating.
- 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.
- 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.
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 for 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.
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 walls--by
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 weather boards. 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 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 weatherboards,
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 preparation 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 features. This custom fitting
of the siding will be more labor-intensive, 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 abovementioned 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 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" have been published and are available from National Park Service
Regional Offices and State Historic Preservation Offices. Further, since
rehabilitation projects for income-producing historic buildings often
seek tax benefits 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
long-lasting 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 Laboratory USDA, 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. Washington, D.C.
Last Modified:
January 30, 1998
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