Detail of restored roof; Link to Parknet
STANDARDS FOR RESTORATION AND GUIDELINES FOR RESTORING HISTORIC BUILDINGS
<photo> detail of historic tile roofing

Identify    Protect    Repair    Replace    Remove   Re-Create

Identify, Retain and Preserve

Recommend
Identifying, retaining, and preserving roofs and roof features from the restoration period. This includes the roof's shape, such as hipped, gambrel, and mansard; decorative features such as cupolas, cresting, chimneys, and weathervanes; and roofing material such as slate, wood, clay tile, and metal, as well as size, color, and patterning.

photo of distinctive tapered barrel clay roof tiles

Clay tiles are one of the most distinctive and decorative historic
roofing materials because of their great variety of shapes, colors, profiles, patterns, and textures. Tapered barrel clay roof tiles were custom made for the restoration of the 1820s Indian barracks at Mission Santa Cruz. Photo: NPS files.

Not Recommended
Altering roofs and roof features from the restoration period.

Failing to properly document roof features from the restoration period which may result in their loss.

Changing the type or color of roofing materials unless the work can be substantiated by historical documentation.

Protect and Maintain

Recommend
Protecting and maintaining a restoration period roof by cleaning the gutters and downspouts and replacing deteriorated flashing. Roof sheathing should also be checked for proper venting to prevent moisture condensation and water penetration; and to insure that materials are free from insect infestation.

Providing adequate anchorage for roofing material to guard against wind damage and moisture penetration.

photo showing a historic house with partially destroyed slate roofing after a hurricane

After a hurricane or other natural disaster, it may be necessary to stabilize a roof temporarily until materials can be obtained and a qualified roofing contractor hired. Significant slate roofs should not be stripped off and replaced with asphalt shingles. Photo: NPS files.

Protecting a leaking roof with plywood and building paper until it can be properly repaired.

Evaluating the existing condition of materials to determine whether more than protection and maintenance are required, that is, if repairs to roofs and roof features will be necessary.

Not Recommended
Failing to clean and maintain gutters and downspouts properly so that water and debris collect and cause damage to roof fasteners, sheathing, and the underlying structure.

Allowing roof fasteners, such as nails and clips to corrode so that roofing material is subject to accelerated deterioration.

Permitting a leaking roof to remain unprotected so that accelerated deterioration of historic building materials--masonry, wood, plaster, paint and structural members--occurs.

Failing to undertake adequate measures to assure the protection of roofs and roof features from the restoration period.

Repair

Recommend
Repairing a roof from the restoration period by reinforcing the materials which comprise roof features. Repairs will also generally include the limited replacement in kind--or with compatible substitute material--of those extensively deteriorated or missing parts of features when there are surviving prototypes such as cupola louvers, dentils, dormer roofing; or slates, tiles, or wood shingles. The new work should be unobtrusively dated to guide future research and treatment.

photo of new slate being installed as part of a roof restoration project

Within a roof restoration project, a severly deteriorated slate has been removed; the new slate is being secured with a nail. Photo: Jeffrey S. Levine.

Not Recommended
Replacing an entire roof feature from the restoration period such as a cupola or dormer when the repair of materials and limited replacement of deteriorated or missing parts are appropriate.

Failing to reuse intact slate or tile when only the roofing substrate needs replacement.

Using a substitute material for the replacement part that does not convey the visual appearance of the surviving parts of the roof or that is physically or chemically incompatible.

photo of inappropriate roofing shingles with rustic split faces

Commercially available modern shingles and shakes are for the most part machine-made. Roofing products with rustic split faces are not appropriate for historic preservation projects. Photo: NPS files.

 

Replace

Recommend
Replacing in kind an entire roof feature from the restoration period that is too deteriorated to repair--if the overall form and detailing are still evident--using the physical evidence as a model to reproduce the feature. Examples can include a large section of roofing, or a dormer or chimney. If using the same kind of material is not technically or economically feasible, then a compatible substitute material may be considered. The new work should be unobtrusively dated to guide future research and treatment.

paired photos of roof restoration project showing appropriate matching replacement shinges

(left) These weathered historic 19th-century handsplit and dressed shingles were found in place under a later, altered, roof. (right) In the restoration, these replacement shingles matched the historic shingles and were of such high quality that little hand dressing was needed at the site. Photos: John Ingle..

Not Recommended
Removing a roof feature from the restoration period that is unrepairable, and not replacing it; or failing to document the new work.

The following Restoration work involves the removal or alteration of existing historic roofs and roof features that would be retained in Preservation and Rehabilitation treatments; and the replacement of missing roof features from the restoration period using all new materials in order to create an accurate historic appearance.

Removing Existing Features from Other Historic Periods

Recommend
Removing or altering roofs or roof features from other historic periods such as a later dormer or asphalt roofing.

Documenting materials and features dating from other periods prior to their alteration or removal. If possible, selected examples of these features or materials should be stored to facilitate future research.

Not Recommended
Failing to remove a roof feature from another period, thus confusing the depiction and of the building's significance.

Failing to document roofing materials and roof features from other historic periods that are removed from the building so that a valuable portion of the historic record is lost.

Re-creating Missing Features from the Restoration Period

Recommend
Re-creating missing roofing material or a roof feature that existed during the restoration period based on physical or documentary evidence; for example, duplicating a dormer or cupola.

paired photos of the Camron-Staford House, Oakland, CA, before and after roof restoration

Restoration of the Camron-Stanford House, Oakland, California, focused on the replacement of missing roof cresting and chimneys from the restoration period, based on careful documentation. Photo: Before, NPS files; After, Courtesy, James B. Spaulding.

Not Recommended
Constructing a roof feature that was part of the original design for the building, but was never actually built; or constructing a feature which was thought to have existed during the restoration period, but for which there is insufficient documentation.

 

-GUIDELINES-

The Approach

Exterior Materials
Masonry
Wood
Architectural Metals

Exterior Features
Roofs
Windows
Entrances + Porches
Storefronts

Interior Features
Structural System Spaces/Features/Finishes
Mechanical Systems

Site

Setting

Special Requirements
Energy Efficiency
Accessibility
Health + Safety

The Standards

 

  HISTORICAL OVERVIEW - PRESERVING - REHABILITATING - restoring- RECONSTRUCTING

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Historical Overview