Attachment_7_Secretary_of_Interior_Guidelines_for_Restoration_0001.pdf

RESTORATION

STANDARDS FOR RESTORATION &

GUIDELINES FOR RESTORING HISTORIC BUILDINGS

Restoration Restoration is defined as the act or process of accurately depicting the form, features, and character of a property as it appeared at a particular period of time by means of the removal of features from other periods in its history and reconstruction of missing features from the restoration period. The limited and sensitive upgrading of mechanical, electrical, and plumbing systems and other code-required work to make properties functional is appropriate within a restoration project.

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Repair Old Chief Joseph Wall Nez Perce National Historical Park

Standards for Restoration

1. A property will be used as it was historically or be given a new use that interprets the property and its restoration period.

2. Materials and features from the restoration period will be retained and preserved. The removal of materials or alteration of features, spaces and spatial relationships that charac terize the period will not be undertaken.

3. Each property will be recognized as a physical record of its time, place and use. Work needed to stabilize, consolidate and conserve materials and features from the restoration period will be physically and visually compatible, identifiable upon close inspection and properly documented for future research.

4. Materials, features, spaces and finishes that characterize other historical periods will be documented prior to their alteration or removal.

5. Distinctive materials, features, finishes and construction techniques or examples of craftsmanship that characterize the restoration period will be preserved.

6. Deteriorated features from the restoration period will be repaired rather than replaced.

Where the severity of deterioration requires replacement of a distinctive feature, the new feature will match the old in design, color, texture and, where possible, materials.

7. Replacement of missing features from the restoration period will be substantiated by documentary and physical evidence. A false sense of history will not be created by adding conjectural features, features from other properties, or by combining features that never existed together historically.

8. Chemical or physical treatments, if appropriate, will be undertaken using the gentlest means possible. Treatments that cause damage to historic materials will not be used.

9. Archeological resources affected by a project will be protected and preserved in place. If such resources must be disturbed, mitigation measures will be undertaken.

10. Designs that were never executed historically will not be constructed.

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GUIDELINES FOR RESTORING HISTORIC BUILDINGS

INTRODUCTION

Restoration is the treatment that should be followed when the expressed goal of the project is to make the building appear as it did at a particular—and at its most significant—time in its his tory. The guidance provided by the Standards for Restoration and Guidelines for Restoring Historic Buildings is to first identify the materials and features from the restoration period. After these materi als and features have been identified, they should be maintained, protected, repaired, and replaced, when necessary. Unlike the other treatments in which most, if not all, of the historic elements are retained, restoration will likely include the removal of features from other periods. Missing features from the restoration period should be replaced, based on physical or historic documentation, with either the same or compatible substitute materials. Only those designs that can be documented as having been built should be recreated in a restoration project.

Identify, Retain, and Preserve Materials and Features from the Restoration Period The guidance for the treatment Restoration begins with recom mendations to identify the form and detailing of those architectural materials and features that are significant to the restoration period as established by historic research and documentation. Therefore, guidance on identifying, retaining, and preserving features from the restoration period is always given first.

Protect and Maintain Materials and Features from the Restoration Period After identifying those materials and features from the restoration period that must be retained in the process of Restoration work, then protecting and maintaining them are addressed. Protection generally involves the least degree of intervention and is prepara tory to other work. Protection includes the maintenance of materi als and features from the restoration period as well as ensuring that the property is protected before and during restoration work. An overall evaluation of the physical condition of the features from the restoration period should always begin at this level.

Repair (Stabilize, Consolidate, and Conserve) Materials and Features from the Restoration Period Next, when the physical condition of restoration-period features requires additional work, repairing by stabilizing, consolidating, and conserving is recommended. Restoration guidance focuses on the preservation of those materials and features that are signifi cant to the period. In Restoration, repair may include the limited replacement in kind or with a compatible substitute material of extensively deteriorated or missing components of existing restoration-period features when there are surviving prototypes to use as a model.

INTRODUCTION

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Replace Extensively Deteriorated Features from the Restoration Period In Restoration, replacing an entire feature from the restoration period, such as a porch, that is too deteriorated to repair may be appropriate. Together with documentary evidence, the form and detailing of the historic feature should be used as a model for the replacement. Using the same kind of material is preferred; however, compatible substitute material may be considered. New work may be unobtrusively dated to guide future research and treatment.

Remove Existing Features from Other Historic Periods Most buildings change over time, but in Restoration the goal is to depict the building as it appeared at the most significant time in its history. Thus, it may involve removing or altering existing historic features that do not represent the restoration period. Materials, fea tures, spaces, and finishes that characterize other historical periods should be documented to guide future research and treatment prior to their alteration or removal.

Recreate Missing Features from the Restoration Period Most Restoration projects involve recreating features that were significant to the building during the restoration period, such as a porch, but are now missing. Missing features to be replaced should be substantiated by documentary and physical evidence to ensure the restoration is accurate. Using the same materials to depict lost features is always the preferred approach; however, using compat ible substitute material is an acceptable alternative in Restoration because the goal of this treatment is to replicate the appearance of the historic building at a particular time.

If documentary and physical evidence are not available to provide an accurate recreation of missing features, the treatment Rehabilitation might be a better overall approach to project work.

Code-Required Work:

Accessibility and Life Safety Sensitive solutions to meeting code requirements in a Restoration project are an important part of protecting the historic character of the building. Work that must be done to meet accessibility and life-safety requirements must also be assessed for its potential impact on the historic building as it is restored.

Resilience to Natural Hazards Resilience to natural hazards should be addressed as part of a Resto ration project. A historic building may have existing characteristics or features that help to address or minimize the impacts of natu ral hazards. These should always be used to best advantage when planning new adaptive treatments that have the least impact on the historic character of the building, its site, and setting.

Sustainability Sustainability should be addressed as part of a Restoration project.

Good preservation practice is often synonymous with sustainability.

Existing energy-efficient features should be retained and repaired.

New sustainability treatments should generally be limited to updat ing existing features and systems to have the least impact on the historic character of the building.

The topic of sustainability is addressed in detail in The Secretary of the Interior’s Standards for Rehabilitation & Illustrated Guidelines on Sustainability for Rehabilitating Historic Buildings. Although specifi cally developed for the treatment Rehabilitation, the Sustainability Guidelines can be used to help guide the other treatments.

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Restoration as a Treatment. When the property’s design, architectural, or historical significance during a particular period of time outweighs the potential loss of extant materials, features, spaces, and finishes that characterize other historical periods; when there is substantial physical and documentary evidence for the work; and when contemporary altera tions and additions are not planned, Restoration may be considered as a treatment. Prior to undertaking work, a particular period of time, i.e., the restoration period, should be selected and justified, and a documentation plan for Restoration developed.

INTRODUCTION

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MASONRY: STONE, BRICK, TERRA COTTA, CONCRETE, ADOBE, STUCCO, AND MORTAR

RECOMMENDED NOT RECOMMENDED

Identifying, retaining and preserving masonry features from the restoration period (such as walls, brackets, railings, cornices, window and door surrounds, steps, and columns) and decorative ornament and other details, such as tooling and bonding pat terns, coatings, and color.

Altering masonry features from the restoration period.

Failing to document masonry features from the restoration period, which may result in their loss.

Applying paint or other coatings (such as stucco) to restoration-period masonry features, or removing them, if such treatments cannot be documented to the restoration period.

Changing the type of paint or coating or the color of restoration-period masonry features, unless the work can be substantiated by historical documentation.

Protecting and maintaining masonry features from the resto ration period by ensuring that historic drainage features and systems that divert rainwater from masonry surfaces (such as roof overhangs, gutters, and downspouts) are intact and functioning properly.

Failing to identify and treat the causes of masonry deterioration, such as leaking roofs and gutters or rising damp.

[1] (a) When it was acquired by the National Trust for Historic Preservation in the 1980s, Montpelier in Montpelier Station, VA, the home of James and Dolley Madison, had been much altered and enlarged since it was first constructed. Based on historical documentation and research, Montpelier was accurately restored to its 1820s appearance when the president and his wife lived there (b). Photos: Courtesy of The Montpelier Foundation.

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Cleaning masonry only when necessary to halt deterioration or remove heavy soiling.

Cleaning masonry surfaces from the restoration period when they are not heavily soiled to create a “like-new” appearance, thereby need lessly introducing chemicals or moisture into historic materials.

Carrying out masonry cleaning tests when it has been determined Cleaning masonry surfaces without testing or without sufficient time that cleaning is appropriate. Test areas should be examined for the testing results to be evaluated.

to ensure that no damage has resulted and, ideally, monitored over a sufficient period of time to allow long-range effects to be predicted.

Cleaning soiled restoration-period masonry surfaces with the Cleaning or removing paint from masonry surfaces from the restora gentlest method possible, such as using low-pressure water and tion period using most abrasive methods (including sandblasting, detergent and natural bristle or other soft-bristle brushes. other media blasting, or high-pressure water) which can damage the surface of the masonry and mortar joints.

Using a cleaning or paint-removal method that involves water or liquid chemical solutions when there is any possibility of freezing temperatures.

Cleaning with chemical products that will damage some types of masonry (such as using acid on limestone or marble), or failing to neutralize or rinse off chemical cleaners from masonry surfaces.

Using biodegradable or environmentally-safe cleaning or paint-removal products.

Using paint-removal methods that employ a poultice to which paint adheres, when possible, to neatly and safely remove old lead paint.

Using coatings that encapsulate lead paint, when possible, where paint is not required to be removed to meet environmental regulations.

Allowing only trained conservators to use abrasive or laser clean ing methods, when necessary, to clean hard-to-reach, highly-carved, or detailed decorative stone features.

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Removing damaged or deteriorated paint only to the next sound layer using the gentlest method possible (e.g., hand scraping) prior to repainting.

Removing paint that is firmly adhered to masonry surfaces.

Applying compatible paint coating systems to historically-painted, restoration-period masonry following proper surface preparation.

Failing to follow manufacturers’ product and application instruc tions when repainting masonry features.

Repainting historically-painted masonry features with colors that are documented to the restoration period of the building (i.e., verifying through paint analysis).

Using paint colors on historically-painted masonry features that are not documented to the restoration period.

Protecting adjacent restoration-period materials when cleaning or removing paint from masonry features from the restoration period.

Failing to protect adjacent restoration-period materials when clean ing or removing paint from masonry features from the restoration period.

Evaluating the overall condition of masonry from the restoration period to determine whether more than protection and mainte nance, such as repairs to masonry features will be necessary.

Failing to undertake adequate measures to ensure the protection of masonry features from the restoration period.

Repairing masonry features from the restoration period by patch ing, splicing, consolidating, or otherwise reinforcing the masonry using recognized preservation methods. Repair may include the limited replacement in kind or with a compatible substitute material of those extensively deteriorated or missing compo nents of masonry features from the restoration period when there are surviving prototypes (such as terra-cotta brackets or stone balusters) or when the replacement can be based on physical or historic documentation. The new work should match the old in material, design, scale, color, and finish.

Removing masonry from the restoration period that could be stabi lized, repaired, and conserved, or using untested consolidants and unskilled personnel, potentially causing further damage to materials.

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Repairing masonry walls and other masonry features from the restoration period by repointing the mortar joints where there is evidence of deterioration, such as disintegrating mortar, cracks in mortar joints, loose bricks, or damaged plaster.

Removing deteriorated lime mortar from the restoration period Removing restoration-period mortar that is not deteriorated from carefully by hand raking the joints to avoid damaging the sound joints.

masonry.

[2] (a) Decatur House in Washington, DC, was designed by William Henry Latrobe and constructed in 1816. (b) In the late-19th century, the façade was “modernized” by removing the limestone lintels on the first floor and replacing them with decorative sandstone lintels in the style of the period. (c) In the mid-20th century, the house was brought back to its original appearance based on historic documentation.

Photos: The White House Historical Association and Decatur House, a National Trust Site.

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Using power tools only on horizontal joints on restoration-period brick masonry in conjunction with hand chiseling to remove hard mortar that is deteriorated or that is a non-historic material which is causing damage to the masonry units. Mechanical tools should be used only by skilled masons in limited circumstances and generally not on short, vertical joints in brick masonry.

Allowing unskilled workers to use masonry saws or mechanical tools to remove deteriorated mortar from joints prior to repointing.

Duplicating historic mortar joints in strength, composition, color, Repointing masonry units with mortar of high Portland cement and texture when repointing is necessary. In some cases, a lime- content (unless it is the content of the mortar from the restoration based mortar may also be considered when repointing Portland period).

cement mortar joints because it is more flexible.

Duplicating restoration-period mortar joints in width and joint profile when repointing is necessary.

Using “surface grouting” or a “scrub” coating technique, such as a “sack rub” or “mortar washing,” to repoint exterior masonry units from the restoration period instead of traditional repointing methods.

Changing the width or joint profile when repointing masonry from the restoration period.

[3] Not Recommended:

Although the Dutchman stone repair has been well executed, the replacement stone is not a good color match.

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Repairing stucco from the restoration period by removing the Removing sound stucco from the restoration period or repairing with damaged material and patching with new material that duplicates new stucco that is different in composition from the historic stucco.

the historic stucco in strength, composition, color, and texture.

Patching stucco or concrete from the restoration period without removing the source of deterioration.

Replacing deteriorated stucco from the restoration period with synthetic stucco, an exterior finish and insulation system (EFIS), or other non-traditional materials.

Using mud plaster or a compatible lime-plaster adobe render, when appropriate, to repair adobe from the restoration period.

Applying cement stucco, unless it already exists, to adobe from the restoration period.

Sealing joints in concrete from the restoration period with appro priate flexible sealants and backer rods, when necessary.

Repointing masonry units from the restoration period (other than concrete) with a synthetic caulking compound instead of mortar.

Cutting damaged concrete from the restoration period back to Patching concrete from the restoration period without removing the remove the source of deterioration, such as corrosion on metal source of deterioration.

reinforcement bars. The new patch must be applied carefully so that it will bond satisfactorily with and match the historic concrete.

Using a non-corrosive, stainless-steel anchoring system when replacing damaged stone, concrete, or terra-cotta units from the restoration period that have failed.

Repairing masonry features from the restoration period by patch- Removing masonry from the restoration period that could be sta ing, splicing, consolidating, or otherwise reinforcing the masonry bilized, repaired, and conserved, or using untested consolidants, using recognized preservation methods. Repair may include improper repair techniques, or unskilled personnel, potentially the limited replacement in kind or with a compatible substitute causing further damage to materials.

material of those extensively deteriorated or missing compo nents of masonry features from the restoration period when there Replacing an entire masonry feature from the restoration period, are surviving prototypes (such as terra-cotta brackets or stone such as a cornice or balustrade, when repair of the masonry and balusters) or when the replacement can be based on physical or limited replacement of deteriorated or missing components are historic documentation. The new work should match the old in appropriate.

material, design, scale, color, and finish.

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[4] (a) Over the years terra-cotta cladding had been replaced on the lower floors of this early-20th century bank building with a storefront and incompatible windows. (b) A 1936 photograph of the building provided the documentation to restore its historic appearance.

(c) Glass fiber reinforced plastic (GRFP) was chosen as a substitute material, and samples were made in a variety of colors and textures to obtain the best match for the missing and damaged terra cotta. (d) This photo taken after restoration shows that the GFRP replacements successfully blend in with the original terra cotta.

Photo (d): Blamonet at English Wikipedia.

(a)

(c)

(d) (b)

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Applying non-historic surface treatments, such as water-repellent Applying waterproof, water-repellent, or other coatings that are not coatings, to masonry from the restoration period only after from the restoration period (such as stucco) to masonry as a substi repointing and only if masonry repairs have failed to arrest water tute for repointing and masonry repairs.

penetration problems.

Applying permeable, anti-graffiti coatings to masonry from the restoration period when appropriate.

Applying water-repellent or anti-graffiti coatings that change the historic appearance of the masonry from the restoration period or that may trap moisture if the coating is not sufficiently permeable.

Replacing in kind an entire masonry feature from the restoration Removing a masonry feature from the restoration period that is period that is too deteriorated to repair (if the overall form and unrepairable and not replacing it, or replacing it with a new feature detailing are still evident) using the physical evidence as a model that does not match.

to reproduce the feature. Examples can include a large section of a wall, a cornice, balustrade, pier, or parapet. If using the same Using a substitute material for the replacement that does not kind of material is not feasible, then a compatible substitute convey the same appearance of the surviving components of the material may be considered. The new work may be unobtrusively masonry.

dated to guide future research and treatment.

The following Restoration work is highlighted to indicate that it involves the removal or alteration of existing historic masonry features that would be retained in Preservation and Rehabilitation treatments; and the replacement of missing masonry features from the restoration period using all new materials.

Removing Existing Features from Other Historic Periods

Removing masonry features from other historic periods, such as a door surround, porch, or steps.

Failing to remove a masonry feature from another period, thereby confusing the depiction of the building’s appearance from the restoration period.

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

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

Recreating Missing Features from the Restoration Period

Recreating a missing masonry feature that existed during the Constructing a masonry feature that was part of the original design restoration period based on documentary and physical evidence; for the building but was never actually built, or a feature which for example, duplicating a terra-cotta bracket or stone balus was thought to have existed during the restoration period but which trade. The new work may be unobtrusively dated to guide future cannot be documented.

research and treatment.

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WOOD: CLAPBOARD, WEATHERBOARD, SHINGLES, AND

OTHER FUNCTIONAL AND DECORATIVE ELEMENTS

RECOMMENDED NOT RECOMMENDED

Identifying, retaining, and preserving wood features from the res- Altering wood features from the restoration period.

toration period (such as siding, cornices, brackets, window and door surrounds, and steps) and their paints, finishes, and colors. Failing to document wood features from the restoration period, which may result in their loss.

Applying paint or other coatings to restoration-period wood features, or removing them, if such treatments cannot be documented to the restoration period.

Changing the type of paint or coating or the color of restoration-period wood features, unless the work can be substantiated by historical documentation.

Protecting and maintaining wood features from the restoration period by ensuring that historic drainage features that divert rain water from wood surfaces (such as roof overhangs, gutters, and downspouts) are intact and functioning properly.

Failing to identify and treat the causes of wood deterioration, such as faulty flashing, leaking gutters, cracks and holes in siding, dete riorated caulking in joints and seams, plant material growing too close to wood surfaces, or insect or fungal infestation.

Applying chemical preservatives or paint to wood features from the restoration period that are subject to weathering, such as exposed beam ends, outriggers, or rafter tails.

Using chemical preservatives that can change the appearance of wood features from the restoration period.

Implementing an integrated pest management plan to identify appropriate preventive measures to guard against insect damage, such as installing termite guards, fumigating, and treating with chemicals.

Retaining coatings from the restoration period (such as paint) that protect the wood from moisture and ultraviolet light. Paint removal should be considered only when there is paint surface deterioration and as part of an overall maintenance program which involves repainting or applying other appropriate coatings.

Stripping restoration-period paint or other coatings from wood fea tures without recoating them.

Using biodegradable or environmentally-safe cleaning or paint-removal products.

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RECOMMENDED NOT RECOMMENDED

Using thermal devices (such as infrared heaters) carefully to Using a thermal device to remove paint from wood features without remove paint, when it is so deteriorated that total removal is first checking for and removing any flammable debris behind them.

necessary prior to repainting.

Using thermal devices without limiting the amount of time the wood is exposed to heat.

Using paint-removal methods that employ a poultice to which paint adheres, when possible, to neatly and safely remove old lead paint.

Using coatings that encapsulate lead paint, when possible, where the paint is not required to be removed to meet environmental regulations.

Using chemical strippers primarily to supplement other methods Failing to neutralize the wood thoroughly after using chemical paint such as hand scraping, hand sanding, and thermal devices. removers so that new paint may not adhere.

Removing paint from detachable, restoration-period wood features by soaking them in a caustic solution which can roughen the sur face, split the wood, or result in staining from residual acid leach ing out through the wood.

Removing damaged or deteriorated paint to the next sound layer Using potentially-damaging paint-removal methods on restoration-using the gentlest method possible (e.g., hand scraping and hand period wood surfaces, such as open-flame torches, orbital sanders, sanding) prior to repainting. abrasive methods (including sandblasting, other media blasting, or high-pressure water), or caustic paint-removers.

Removing paint that is firmly adhered to wood surfaces.

Applying compatible paint coating systems to historically-painted wood following proper surface preparation.

Failing to follow manufacturers’ product and application instruc tions when repainting wood features from the restoration period.

Repainting historically-painted wood features with colors that are documented to the restoration period of the building (i.e., verify ing through paint analysis).

Using paint colors on historically-painted wood features that are not documented to the restoration period.

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RECOMMENDED NOT RECOMMENDED

Protecting adjacent restoration-period materials when cleaning or removing paint from wood features from the restoration period.

Failing to protect adjacent restoration-period materials when cleaning or removing paint from wood features from the restoration period.

Evaluating the overall condition of wood features from the res toration period to determine whether more than protection and maintenance, such as repairs to wood features, will be necessary.

Failing to undertake adequate measures to ensure the protection of wood features from the restoration period.

Repairing wood features from the restoration period by patching, Removing wood features from the restoration period that could be splicing, consolidating, or otherwise reinforcing the wood using stabilized, repaired, and conserved, or using untested consolidants recognized preservation methods. Repair may include the limited or unskilled personnel, potentially causing further damage to his-replacement in kind or with a compatible substitute material of toric materials.

those extensively deteriorated or missing components of features from the restoration period when there are surviving prototypes Replacing an entire wood feature from the restoration period, such (such as brackets, molding, or sections of siding) or when the as a cornice or porch railing, when repair of the wood and limited replacement can be based on physical or historic documentation. replacement of deteriorated or missing components are appropriate.

The new work should match the old in material, design, scale, color, and finish.

Replacing in kind an entire wood feature from the restoration Removing a wood feature from the restoration period that is unre period that is too deteriorated to repair (if the overall form and pairable and not replacing it, or replacing it with a new feature that detailing are still evident) using the physical evidence as a model does not match.

to reproduce the feature or when the replacement can be based on historic documentation. Examples can include a cornice, Using substitute material for the replacement that does not convey entablature, or a balustrade. If using the same kind of material the same appearance of the surviving components of the wood fea is not feasible, then a compatible substitute material may be ture from the restoration period or that is physically incompatible.

considered. The new work may be unobtrusively dated to guide future research and treatment.

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RECOMMENDED NOT RECOMMENDED

The following Restoration work is highlighted to indicate that it involves the removal or alteration of existing historic masonry features that would be retained in Preservation and Rehabilitation treatments; and the replacement of missing wood features from the restoration period using all new materials.

Removing Existing Features from Other Historic Periods

Removing wood features from other historic periods, such as a door surround, porch, or steps.

Failing to remove a wood feature from another period, thereby con fusing the depiction of the building’s appearance from the restora tion period.

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

Recreating Missing Features from the Restoration Period

Recreating a missing wood feature that existed during the resto ration period based on documentary and physical evidence; for example, duplicating a wood dormer or porch

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

Constructing a wood feature that was part of the original design for the building but was never actually built, or a feature which was thought to have existed during the restoration period but cannot be documented.

[5] New wood trim pieces were milled to match the few remaining historic features to replace those that were missing.

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METALS: WROUGHT AND CAST IRON, STEEL, PRESSED METAL, TERNEPLATE,

COPPER, ALUMINUM, AND ZINC

RECOMMENDED NOT RECOMMENDED

Identifying, retaining, and preserving metal features from the restoration period (such as columns, capitals, pilasters, spandrel panels, or stairways) and their finishes and colors. The type of metal should be identified prior to work because each metal has its own properties and may require a different treatment.

Altering metal features from the restoration period.

Failing to document metal features from the restoration period, which may result in their loss.

Applying paint or other coatings to restoration-period metal fea tures, or removing them, if such treatments cannot be documented to the restoration period.

Changing the type of paint or coating or the color of restoration-period metal features, unless the work can be substantiated by historical documentation.

Protecting and maintaining metals from the restoration period Failing to identify and treat the causes of corrosion of restoration-from corrosion by providing proper drainage so that water does period metal features such as moisture from leaking roofs or gut-not stand on flat, horizontal surfaces or accumulate in curved ters.

decorative features.

Cleaning metals from the restoration period, when necessary, to remove corrosion prior to repainting or applying other appropriate protective coatings.

Failing to reapply coating systems after cleaning metals from the restoration period that require protection from corrosion.

Removing the patina from restoration-period metal features. The patina may be a protective layer on some metals (such as bronze or copper) as well as a distinctive finish.

Identifying the particular type of metal from the restoration Using cleaning methods which alter or damage the restoration-period prior to any cleaning procedure and then testing to ensure period color, texture, and finish of the metal, or cleaning when it is that the gentlest cleaning method possible is selected; or alterna inappropriate for the metal.

tively, determining that cleaning is inappropriate for the particu lar metal.

Using non-corrosive chemical methods to clean soft metals from Cleaning soft metals from the restoration period (such as lead, tin-the restoration period (such as lead, tinplate, terneplate, copper, plate, terneplate, copper, and zinc) with abrasive methods (includ and zinc) whose finishes can be easily damaged by abrasive ing sandblasting, other media blasting, or high-pressure water) methods. which will damage the surface of the metal.

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RECOMMENDED NOT RECOMMENDED

Using the least abrasive cleaning method on hard metals from the restoration period (such as cast iron, wrought iron, and steel) to remove paint buildup and corrosion. If hand scraping and wire brushing have Using the least abrasive cleaning method on hard metals from the restoration period (such as cast iron, wrought iron, and steel) to remove paint buildup and corrosion. If hand scraping and wire brushing have proven ineffective, low-pressure abrasive methods may be used as long as they do not damage the surface.

Using high-pressure abrasive techniques without first trying gentler cleaning methods prior to cleaning cast iron, wrought iron, or steel.

Applying appropriate paint or other coating systems to histori cally-painted, restoration-period metal features after cleaning to protect them from corrosion.

Applying paint or other coatings to metals (such as copper, bronze, or stainless steel) if they were not coated during the restoration period.

Repainting historically-painted metal features with colors that are documented to the restoration period of the building (i.e., verify ing through paint analysis).

Using paint colors on historically-painted metal features that are not documented to the restoration period of the building.

Applying an appropriate protective coating (such as lacquer or wax) to an architectural metal feature that was historically unpainted, such as a bronze door, that is subject to heavy use.

Protecting adjacent restoration-period materials when working on metal features from the restoration period.

Failing to protect adjacent restoration-period materials when work ing on metal features from the restoration period.

Evaluating the overall condition of metals from the restoration period to determine whether more than protection and mainte nance, such as repairs to metal features, will be necessary.

Failing to undertake adequate measures to ensure the protection of metal features from the restoration period.

Repairing metal features from the restoration period by reinforc- Removing metal features from the restoration period that could be ing the metal by using recognized preservation methods. Repair stabilized, repaired, and conserved, or using improper repair tech-may include the limited replacement in kind or with a compatible niques, or untrained personnel, potentially causing further damage substitute material of those extensively deteriorated or missing to historic materials.

parts of features when there are surviving prototypes (such as porch balusters, column capitals or bases, storefronts, railings, or Replacing an entire metal feature from the restoration period, such porch cresting) or when the replacement can be based on physi as a column or balustrade, when repair of the metal and limited cal or historic documentation. The new work should match the replacement of deteriorated or missing components are appropriate.

old in material, design, scale, color, and finish.

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[6] Preliminary work before starting restoration revealed that the columns and the decorative shingles ornamenting the top floor of this historic building were fabricated of metal to imitate the red sandstone used elsewhere on the building.

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RECOMMENDED NOT RECOMMENDED

Replacing in kind an entire metal feature from the restoration Removing a metal feature from the restoration period that is unre period that is too deteriorated to repair (if the overall form and pairable and not replacing it, or replacing it with a new feature that detailing are still evident) using the physical evidence as a model does not match.

to reproduce the feature or when the replacement can be based on historic documentation. Examples of such a feature could Using a substitute material for the replacement that does not include cast-iron porch steps or steel-sash windows. If using the convey the same appearance of the surviving components of the same kind of material is not feasible, then a compatible sub- metal feature from the restoration period or that is physically or stitute material may be considered as long as it has the same chemically incompatible.

appearance as the original. The new work may be unobtrusively dated to guide future research and treatment.

The following Restoration work is highlighted to indicate that it involves the removal or alteration of existing historic masonry features that would be retained in Preservation and Rehabilitation treatments; and the replacement of missing metal features from the restoration period using all new materials.

Removing Existing Features from Other Historic Periods

Removing metal features from other historic periods, such as a cast-iron porch railing or aluminum windows.

Failing to remove a metal feature from another period, thereby con fusing the depiction of the building’s appearance from the restora tion period.

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

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

Recreating Missing Features from the Restoration Period

Recreating a missing metal feature that existed during the resto- Constructing a metal feature that was part of the original design for ration period based on documentary and physical evidence; for the building but was never actually built, or a feature which was example, duplicating a cast-iron storefront or porch. thought to have existed during the restoration period but cannot be documented.

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ROOFS

Identifying, retaining, and preserving roofs from the restoration Altering roof and roofing materials from the restoration period.

period and their functional and decorative features. The form of the roof (gable, hipped, gambrel, flat, or mansard) is significant, Failing to document roof features from the restoration period, which as are its decorative and functional features (such as cupolas, may result in their loss.

cresting, parapets, monitors, chimneys, weather vanes, dormers, ridge tiles, and snow guards), roofing materials (such as slate, Changing the type of paint or coating or the color of restoration-wood, clay tile, metal, roll roofing, or asphalt shingles) and size, period roof features, unless the work can be substantiated by color, and patterning. historical documentation.

Stripping the roof of sound historic roofing material (such as slate, clay tile, wood, or metal) from the restoration period.

Protecting and maintaining a roof from the restoration period Failing to clean and maintain gutters and downspouts so that water by cleaning gutters and downspouts and replacing deteriorated and debris collect and cause damage to roof fasteners, sheathing, flashing. Roof sheathing should also be checked for indications and the underlying structure.

of moisture due to leaks or condensation.

Providing adequate anchorage for roofing material from the restoration period to guard against wind damage and moisture penetration.

Allowing flashing, caps, and exposed roof fasteners to corrode, which accelerates deterioration.

Protecting a leaking roof with a temporary waterproof membrane with a synthetic underlayment, roll roofing, plywood, or a tarpau lin until it can be repaired.

Leaving a leaking roof unprotected so that accelerated deterioration of historic building materials from the restoration period (such as masonry, wood, plaster, paint, and structural members) results.

Repainting a roofing material from the restoration period that Failing to repaint a roofing material from the restoration period that requires a protective coating and was painted historically (such requires a protective coating and was painted historically as part of as a terneplate metal roof or gutters) as part of regularly-sched regularly-scheduled maintenance.

uled maintenance.

Protecting a restoration-period roof covering when working on other roof features from the restoration period.

Failing to protect restoration-period roof coverings when working on other roof features from the restoration period.

Evaluating the overall condition of the roofing materials from the restoration period to determine whether more than protection and maintenance, such as repairs to roof features, will be necessary.

Failing to undertake adequate measures to ensure the protection of roof features from the restoration period.

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[7 a-b] This crumbling chimney was restored to its historic appearance using matching bricks.

[8] The missing steeple of this historic church was replaced with a new steeple made of a substitute material that, from the street below, closely resembles the original steeple. Photo: en.Wikipedia.

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ROOFS

Repairing a roof from the restoration period by reinforcing the materials that comprise the roof using recognized preservation methods. Repair may include the limited replacement in kind or with a compatible substitute material of those extensively deterio rated or missing components of features when there are surviving prototypes (such as cupola louvers, cresting, dormer roofing, roof monitors, or slate or tile on a main roof) or when replacement can be based on physical or historic documentation. The new work should match the old in materials, design, scale, color, and finish.

Replacing an entire roof feature from the restoration period, such as a dormer, when repair of the roofing materials and limited replace ment of deteriorated or missing components are feasible.

Failing to reuse intact slate or tile from the restoration period when only the roofing substrate or fasteners need replacement.

Replacing in kind an entire roof covering or feature from the Removing a roof feature from the restoration period that is unrepair restoration period that is too deteriorated to repair (if the overall able, such as a chimney or dormer, and not replacing it, or replac form and detailing are still evident) using the physical evidence ing it with a feature that does not match.

as a model to reproduce the feature or when the replacement can be based on historic documentation. Examples of such a feature Using a substitute material for the replacement of a single ele could include a large section of roofing, a dormer, or a chimney. ment of a roof (such as a tile or slate) or an entire feature that does If using the same kind of material is not feasible, then a compat not convey the same appearance of the surviving components of ible substitute material may be appropriate. the roof feature from the restoration period or that is physically or chemically incompatible.

The following Restoration work is highlighted to indicate that it involves the removal or alteration of existing historic masonry 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.

Removing Existing Features from Other Historic Periods

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

Failing to remove a roof feature from another period, thereby con fusing the depiction of the building’s appearance from the restora tion period.

Documenting roof features dating from other periods prior to their Failing to document roofing materials and roof features from other alteration or removal. If possible, selected examples of these historic periods that are removed from the building so that a valu features or materials should be stored for future research. able portion of the historic record is lost.

Recreating Missing Features from the Restoration Period

Recreating a missing roofing material or roof feature that existed Constructing a roof feature that was part of the original design for during the restoration period based on documentary and physical the building but was never actually built, or a feature which was evidence; for example, duplicating a former dormer or cupola. thought to have existed during the restoration period but cannot be documented.

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WINDOWS

Identifying, retaining, and preserving windows from the restora tion period and their functional and decorative features. The window material and how the window operates (e.g., double hung, casement, awning, or hopper) are significant, as are its components (including sash, muntins, ogee lugs, glazing, pane configuration, sills, mullions, hardware, casings or brick molds) and related features, such as shutters.

Altering windows or window features from the restoration period.

Failing to document window features from the restoration period, which may result in their loss.

Applying paint or other coatings to restoration-period window fea tures, or removing them, if such treatments cannot be documented to the restoration period.

Changing the type of paint or coating or the color of restoration-period windows, unless the work can be substantiated by historical documentation.

Stripping windows of sound historic material (such as wood or metal) from the restoration period.

Conducting an in-depth survey of the condition of existing win- Replacing windows from the restoration period solely because of dows from the restoration period early in the planning process so peeling paint, broken glass, stuck sash, or high air infiltration.

that repair, upgrading, and, if necessary, possible replacement These conditions, in themselves, do not indicate that windows are options can be fully explored. beyond repair.

Protecting and maintaining the restoration-period wood or metal Failing to protect and maintain window materials from the restora which comprises the window jamb, sash, and trim through appro tion period on a cyclical basis so that deterioration of the window priate surface treatments such as cleaning, paint removal, and results.

reapplication of the same protective coatings.

Protecting…