Restoration Standards and Guidelines for Historic Buildings · Restoring Historic Buildings is to make the building appear as it did at a particular—and most signifi-cant—time

PDHonline Course A107 (5 PDH)

Restoration Standards and Guidelinesfor Historic Buildings

2012

Instructor: Jeffrey Havelin, PE

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Fairfax, VA 22030-6658Phone & Fax: 703-988-0088

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Standards forRestoration

&Guidelines forRestoringHistoric Buildings

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

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Standards for Restoration

1. A property will be used as it was historically or be given a new use which reflects the property’s restora-tion period.

2. Materials and features from the restoration period will be retained and preserved. The removal ofmaterials or alteration of features, spaces, and spatial relationships that characterize the period will not beundertaken.

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

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

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

6. Deteriorated features from the restoration period will be repaired rather than replaced. Where theseverity of deterioration requires replacement of a distinctive feature, the new feature will match the old indesign, color, texture, and, where possible, materials.

7. Replacement of missing features from the restoration period will be substantiated by documentary andphysical evidence. A false sense of history will not be created by adding conjectural features, features fromother 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 resourcesmust be disturbed, mitigation measures will be undertaken.

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

Guidelines for Restoring Historic Buildings

Introduction

Rather than maintaining and preserving a building asit has evolved over time, the expressed goal of theStandards for Restoration and Guidelines forRestoring Historic Buildings is to make the buildingappear as it did at a particular—and most signifi-cant—time in its history. First, those materials andfeatures from the “restoration period” are identified,based on thorough historical research. Next, featuresfrom the restoration period are maintained, protect-ed, repaired (i.e., stabilized, consolidated, and con-served), and replaced, if necessary. As opposed toother treatments, the scope of work in Restorationcan include removal of features from other periods;missing features from the restoration period may bereplaced, based on documentary and physical evi-dence, using traditional materials or compatible sub-stitute materials. The final guidance emphasizes thatonly those designs that can be documented as havingbeen built should be re-created in a restoration pro-ject.

Identify, Retain, and Preserve Materials andFeatures from the Restoration Period

The guidance for the treatment Restoration beginswith recommendations to identify the form anddetailing of those existing architectural materials andfeatures that are significant to the restoration periodas established by historical research and documenta-tion. Thus, guidance on identifying, retaining, andpreserving features from the restoration period isalways given first. The historic building’s appearancemay be defined by the form and detailing of its exte-rior materials, such as masonry, wood, and metal;exterior features, such as roofs, porches, and windows;

interior materials, such as plaster and paint; and inte-rior features, such as moldings and stairways, roomconfiguration and spatial relationships, as well asstructural and mechanical systems; and the building’ssite and setting.

Protect and Maintain Materials and Features fromthe Restoration Period

After identifying those existing materials and featuresfrom the restoration period that must be retained inthe process of Restoration work, then protecting andmaintaining them is addressed. Protection generallyinvolves the least degree of intervention and ispreparatory to other work. For example, protectionincludes the maintenance of historic material throughtreatments such as rust removal, caulking, limitedpaint removal, and re-application of protective coat-ings; the cyclical cleaning of roof gutter systems; orinstallation of fencing, alarm systems and other tem-porary protective measures. Although a historicbuilding will usually require more extensive work, anoverall evaluation of its physical condition shouldalways begin at this level.

Repair (Stabilize, Consolidate, and Conserve)Materials and Features from the Restoration Period

Next, when the physical condition of restoration peri-od features requires additional work, repairing by sta-bilizing, consolidating, and conserving is recom-mended. Restoration guidance focuses upon thepreservation of those materials and features that aresignificant to the period. Consequently, guidance forrepairing a historic material, such as masonry, againbegins with the least degree of intervention possible,such as strengthening fragile materials through con-solidation, when appropriate, and repointing withmortar of an appropriate strength. Repairing mason-ry as well as wood and architectural metals includes

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patching, splicing, or otherwise reinforcing themusing recognized preservation methods. Similarly,portions of a historic structural system could be rein-forced using contemporary material such as steel rods.In Restoration, repair may also include the limitedreplacement in kind—or with compatible substitutematerial—of extensively deteriorated or missing partsof existing features when there are surviving proto-types to use as a model. Examples could includeterra-cotta brackets, wood balusters, or cast iron fencing.

Replace Extensively Deteriorated Features from theRestoration Period

In Restoration, replacing an entire feature from therestoration period (i.e., a cornice, balustrade, column,or stairway) that is too deteriorated to repair may beappropriate. Together with documentary evidence,the form and detailing of the historic feature shouldbe used as a model for the replacement. Using thesame kind of material is preferred; however, compati-ble substitute material may be considered. All newwork should be unobtrusively dated to guide futureresearch and treatment.

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In a project at Fort Hays, Kansas, the wood frame officers’ quarters were restored to the late 1860s—their period of significance.This included replacing a missing kitchen ell, chimneys, porch columns, and cornice, and closing a later window opening in themain block. The building and others in the museum complex is used to interpret frontier history.

If documentary and physical evidence are not avail-able to provide an accurate re-creation of missing fea-tures, the treatment Rehabilitation might be a betteroverall approach to project work.

Remove Existing Features from Other HistoricPeriods

Most buildings represent continuing occupancies andchange over time, but in Restoration, the goal is todepict the building as it appeared at the most signifi-cant time in its history. Thus, work is included toremove or alter existing historic features that do notrepresent the restoration period. This could includefeatures such as windows, entrances and doors, roofdormers, or landscape features. Prior to altering orremoving materials, features, spaces, and finishes thatcharacterize other historical periods, they should bedocumented to guide future research and treatment.

Re-Create Missing Features from the RestorationPeriod

Most Restoration projects involve re-creating featuresthat were significant to the building at a particulartime, but are now missing. Examples could include astone balustrade, a porch, or cast iron storefront.Each missing feature should be substantiated by doc-umentary and physical evidence. Without sufficientdocumentation for these “re-creations,” an accuratedepiction cannot be achieved. Combining featuresthat never existed together historically can also createa false sense of history. Using traditional materials todepict lost features is always the preferred approach;however, using compatible substitute material is anacceptable alternative in Restoration because, asemphasized, the goal of this treatment is to replicatethe “appearance” of the historic building at a particu-lar time, not to retain and preserve all historic materi-als as they have evolved over time.

If documentary and physical evidence are not avail-able to provide an accurate re-creation of missing fea-tures, the treatment Rehabilitation might be a betteroverall approach to project work.

Energy Efficiency/Accessibility Considerations/Health and Safety Code Considerations

These sections of the Restoration guidance addresswork done to meet accessibility requirements andhealth and safety code requirements; or limited retro-fitting measures to improve energy efficiency.Although this work is quite often an important aspectof restoration projects, it is usually not part of theoverall process of protecting, stabilizing, conserving,or repairing features from the restoration period;rather, such work is assessed for its potential negativeimpact on the building’s historic appearance. For thisreason, particular care must be taken not to obscure,damage, or destroy historic materials or features fromthe restoration period in the process of undertakingwork to meet code and energy requirements.

Restoration as a Treatment. When the property’sdesign, architectural, or historical significance during aparticular period of time outweighs the potential loss ofextant materials, features, spaces, and finishes thatcharacterize other historical periods; when there is sub-stantial physical and documentary evidence for thework; and when contemporary alterations and addi-tions are not planned, Restoration may be considered asa treatment. Prior to undertaking work, a particularperiod of time, i.e., the restoration period, should beselected and justified, and a documentation plan forRestoration developed.

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122 Building Exterior Masonry

Restoration

Building Exterior

Recommended

Identifying, retaining, and preserving masonry features fromthe restoration period such as walls, brackets, railings, cor-nices, window architraves, door pediments, steps, andcolumns; and details such as tooling and bonding patterns,coatings, and color.

Protecting and maintaining masonry from the restorationperiod by providing proper drainage so that water does notstand on flat, horizontal surfaces or accumulate in curveddecorative features.

Cleaning masonry only when necessary to halt deteriorationor remove heavy soiling.

Carrying out masonry surface cleaning tests after it has beendetermined that such cleaning is appropriate. Tests should beobserved over a sufficient period of time so that both theimmediate and the long range effects are known to enableselection of the gentlest method possible.

Masonry: Brick, stone, terra cotta, concrete, adobe, stucco and mortar

Not Recommended

Altering masonry features from the restoration period.

Failing to properly document masonry features from therestoration period which may result in their loss.

Applying paint or other coatings such as stucco to masonryor removing paint or stucco from masonry if such treatmentscannot be documented to the restoration period.

Changing the type or color of the paint or coating unless thework can be substantiated by historical documentation.

Failing to evaluate and treat the various causes of mortar jointdeterioration such as leaking roofs or gutters, differential set-tlement of the building, capillary action, or extreme weatherexposure.

Cleaning masonry surfaces when they are not heavily soiled,thus needlessly introducing chemicals or moisture into his-toric materials.

Cleaning masonry surfaces without testing or without suffi-cient time for the testing results to be of value.

Building Exterior Masonry 123

Restoration

Recommended

Cleaning masonry surfaces with the gentlest method possible,such as low pressure water and detergents, using naturalbristle brushes.

Inspecting painted masonry surfaces to determine whetherrepainting is necessary.

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

Applying compatible paint coating systems following propersurface preparation.

Repainting with colors that are documented to the restora-tion period of the building.

Evaluating the existing condition of the masonry to deter-mine whether more than protection and maintenance arerequired, that is, if repairs to masonry features from therestoration period will be necessary.

Repairing, stabilizing and conserving fragile masonry fromthe restoration period by well-tested consolidants, whenappropriate. Repairs should be physically and visually com-patible and identifiable upon close inspection for futureresearch.

Not Recommended

Sandblasting brick or stone surfaces using dry or wet grit orother abrasives. These methods of cleaning permanentlyerode the surface of the material and accelerate deterioration.

Using a cleaning method that involves water or liquid chemical solutions when there is any possibility of freezingtemperatures.

Cleaning with chemical products that will damage masonry,such as using acid on limestone or marble, or leaving chemi-cals on masonry surfaces.

Applying high pressure water cleaning methods that willdamage historic masonry and the mortar joints.

Removing paint that is firmly adhering to, and thus protect-ing, masonry surfaces.

Using methods of removing paint which are destructive tomasonry, such as sandblasting, application of caustic solu-tions, or high pressure waterblasting.

Failing to follow manufacturers’ product and applicationinstructions when repainting masonry.

Using new paint colors that are not documented to therestoration period of the building.

Failing to undertake adequate measures to assure the protec-tion of masonry features from the restoration period.

Removing masonry from the restoration period that could bestabilized, repaired and conserved; or using untested consoli-dants and untrained personnel, thus causing further damageto fragile historic materials.


Restoration

Recommended

Repairing masonry walls and other masonry features byrepointing the mortar joints where there is evidence of deteri-oration such as disintegrating mortar, cracks in mortar joints,loose bricks, damp walls, or damaged plasterwork.

Removing deteriorated mortar by carefully hand-raking thejoints to avoid damaging the masonry.

Duplicating and, if necessary, reproducing period mortar instrength, composition, color, and texture.

Duplicating and, if necessary, reproducing period mortarjoints in width and in joint profile.

Repairing stucco by removing the damaged material andpatching with new stucco that duplicates stucco of therestoration period in strength, composition, color, andtexture.

Using mud plaster as a surface coating over unfired, unstabi-lized adobe because the mud plaster will bond to the adobe.

Cutting damaged concrete back to remove the source of dete-rioration (often corrosion on metal reinforcement bars). The new patch must be applied carefully so it will bond satisfactorily with, and match, the historic concrete.

Not Recommended

Removing nondeteriorated mortar from sound joints, then repointing the entire building to achieve a uniformappearance.

Using electric saws and hammers rather than hand tools toremove deteriorated mortar from joints prior to repointing.

Repointing with mortar of high portland cement content(unless it is the content of the historic mortar). This canoften create a bond that is stronger than the historic materialand can cause damage as a result of the differing coefficient ofexpansion and the differing porosity of the material and themortar.

Repointing with a synthetic caulking compound.

Using a “scrub” coating technique to repoint instead of tradi-tional repointing methods.

Changing the width or joint profile when repointing.

Removing sound stucco; or repairing with new stucco that isstronger than the historic material or does not convey thesame visual appearance.

Applying cement stucco to unfired, unstabilized adobe.Because the cement stucco will not bond properly, moisturecan become entrapped between materials, resulting in acceler-ated deterioration of the adobe.

Patching concrete without removing the source of deterioration.

Building Exterior Masonry 125

Restoration

Recommended

Repairing masonry features from the restoration period bypatching, piecing-in, or otherwise reinforcing the masonryusing recognized preservation methods. Repair may alsoinclude the limited replacement in kind—or with compatiblesubstitute material—of those extensively deteriorated or miss-ing parts of masonry features from the restoration periodwhen there are surviving prototypes such as terra-cotta brack-ets or stone balusters. The new work should be unobtrusivelydated to guide future research and treatment.

Applying new or non-historic surface treatments such aswater-repellent coatings to masonry only after repointing andonly if masonry repairs have failed to arrest water penetrationproblems.

Not Recommended

Replacing an entire masonry feature from the restorationperiod such as a cornice or balustrade when repair of themasonry and limited replacement of deteriorated or missingparts are appropriate.

Using a substitute material for the replacement part that does not convey the visual appearance of the surviving partsof the masonry feature or that is physically or chemicallyincompatible.

Applying waterproof, water repellent, or non-historic coat-ings such as stucco to masonry as a substitute for repointingand masonry repairs. Coatings are frequently unnecessary,expensive, and may change the appearance of historic mason-ry as well as accelerate its deterioration.

The Meyer May House in Grand Rapids, Michigan, was designed by Frank Lloyd Wright and built in 1909. In 1922, May added to the house foran expanding family. After the May occupancy, the house was altered for use as apartments, with a carport added in 1955. In the 1980s restora-tion, the Wright’s original design was deemed more significant than May’s later changes, and, as a result, the additions were removed and the housereturned to its 1909 appearance. Drawing: Martha L. Werenfels, AIA.

photo 57

BOX RULEPRINTS


Restoration

Recommended

Removing Existing Features from Other Historic Periods

Removing or altering masonry features from other historicperiods such as a later doorway, porch, or steps.

Documenting materials and features dating from other peri-ods prior to their alteration or removal. If possible, selectedexamples of these features or materials should be stored tofacilitate future research.

Re-creating Missing Features from the Restoration Period

Re-creating a missing masonry feature that existed during therestoration period based on physical or documentary evi-dence; for example, duplicating a terra-cotta bracket or stonebalustrade.

Not Recommended

Removing a masonry feature from the restoration period thatis unrepairable and not replacing it.

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

Recommended

Replacing in kind an entire masonry feature from the restora-tion period that is too deteriorated to repair—if the overallform and detailing are still evident—using the physical evi-dence as a model to reproduce the feature. Examples caninclude large sections of a wall, a cornice, balustrade, column,or stairway. If using the same kind of material is not techni-cally or economically feasible, then a compatible substitutematerial may be considered. The new work should be unob-trusively dated to guide future research and treatment.

Not Recommended

Failing to remove a masonry feature from another period,thus confusing the depiction of the building’s significance.

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

Constructing a masonry feature that was part of the originaldesign for the building but was never actually built; or con-structing a feature which was thought to have existed duringthe restoration period, but for which there is insufficient doc-umentation.

Building Exterior Wood 127

Restoration

Building Exterior

Recommended

Identifying, retaining, and preserving wood features fromthe restoration period such as siding, cornices, brackets, window architraves, and doorway pediments; and theirpaints, finishes, and color.

Protecting and maintaining wood features from the restora-tion period by providing proper drainage so that water is notallowed to stand on flat, horizontal surfaces or accumulate indecorative features.

Applying chemical preservatives to wood features such asbeam ends or outriggers that are exposed to decay hazardsand are traditionally unpainted.

Retaining coatings such as paint that help protect the woodfrom moisture and ultraviolet light. Paint removal should beconsidered only where there is paint surface deterioration andas part of an overall maintenance program which involvesrepainting or applying other appropriate protective coatings.

Inspecting painted wood surfaces to determine whetherrepainting is necessary or if cleaning is all that is required.

Removing damaged or deteriorated paint to the next soundlayer using the gentlest method possible (handscraping andhandsanding), then repainting.

Not Recommended

Altering wood features from the restoration period.

Failing to properly document wood features from the restora-tion period which may result in their loss.

Applying paint or other coatings to wood or removing paintfrom wood if such treatments cannot be documented to therestoration period.

Changing the type or color of the paint or coating unless thework can be substantiated by historical documentation.

Failing to identify, evaluate, and treat the causes of wooddeterioration, including faulty flashing, leaking gutters, cracksand holes in siding, deteriorated caulking in joints and seams,plant material growing too close to wood surfaces, or insector fungus infestation.

Using chemical preservatives such as creosote which, unlessthey were used historically, can change the appearance ofwood features.

Stripping paint or other coatings to reveal bare wood, thus exposing historically coated surfaces to the effects ofaccelerated weathering.

Removing paint that is firmly adhering to, and thus, protect-ing wood surfaces.

Using destructive paint removal methods such as propane or butane torches, sandblasting or waterblasting. Thesemethods can irreversibly damage historic woodwork.

Wood: Clapboard, weatherboard, shingles, and other wooden siding and decorative elements

128 Building Exterior Wood

Restoration

Recommended

Using with care electric hot-air guns on decorative wood fea-tures and electric heat plates on flat wood surfaces when paintis so deteriorated that total removal is necessary prior torepainting.

Using chemical strippers primarily to supplement othermethods such as handscraping, handsanding and the above-recommended thermal devices. Detachable wooden elementssuch as shutters, doors, and columns may—with the propersafeguards—be chemically dip-stripped.

Not Recommended

Using thermal devices improperly so that the historic wood-work is scorched.

Failing to neutralize the wood thoroughly after using chemi-cals so that new paint does not adhere.

Allowing detachable wood features to soak too long in a caus-tic solution so that the wood grain is raised and the surfaceroughened.

Ongoing work at this house focuses on the maintenance and repair of exterior wood features fromthe restoration period. After scraping and sanding, the wood was painted in colors documentedto the Restoration period. Photo: ©Mary Randlett, 1992.

Building Exterior Wood 129

Restoration

Recommended

Applying compatible paint coating systems following propersurface preparation.


Evaluating the existing condition of the wood to determinewhether more than protection and maintenance are required,that is, if repairs to wood features from the restoration periodwill be necessary.

Repairing, stabilizing, and conserving fragile wood from therestoration period using well-tested consolidants, whenappropriate. Repairs should be physically and visually com-patible and identifiable upon close inspection for futureresearch.

Repairing wood features from the restoration period bypatching, piecing-in, or otherwise reinforcing the wood usingrecognized preservation methods. Repair may also includethe limited replacement in kind—or with compatible substi-tute material—of those extensively deteriorated or missingparts of features from the restoration period where there aresurviving prototypes such as brackets, molding, or sections ofsiding. The new work should be unobtrusively dated toguide future research and treatment.

Replacing in kind an entire wood feature from the restorationperiod that is too deteriorated to repair—if the overall formand detailing are still evident—using the physical evidence asa model to reproduce the feature. Examples of wood featuresinclude a cornice, entablature or balustrade. If using thesame kind of material is not technically or economically feasi-ble, then a compatible substitute material may be consid-ered. The new work should be unobtrusively dated to guidefuture research and treatment.

Not Recommended

Failing to follow manufacturers’ product and applicationinstructions when repainting exterior woodwork.

Using new colors that are not documented to the restorationperiod of the building.

Failing to undertake adequate measures to assure the protec-tion of wood features from the restoration period.

Removing wood from the restoration period that could bestabilized and conserved; or using untested consolidants anduntrained personnel, thus causing further damage to fragilehistoric materials.

Replacing an entire wood feature from the restoration periodsuch as a cornice or wall when repair of the wood and limitedreplacement of deteriorated or missing parts are appropriate.

Using substitute material for the replacement part that doesnot convey the visual appearance of the surviving parts of thewood feature or that is physically or chemically incompatible.

Removing a wood feature from the restoration period that isunrepairable and not replacing it.

130 Building Exterior Wood

Restoration

Recommended


Removing or altering wood features from other historic periods such as a later doorway, porch, or steps.



Re-creating a missing wood feature that existed during therestoration period based on physical or documentary evi-dence; for example, duplicating a roof dormer or porch.

Not Recommended

Failing to remove a wood feature from another period, thusconfusing the depiction of the building’s significance.

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

Constructing a wood feature that was part of the originaldesign for the building, but was never actually built; or con-structing a feature which was thought to have existed duringthe restoration period, but for which there is insufficient doc-umentation.

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

Building Exterior Metals 131

Restoration

Building Exterior

Recommended

Identifying, retaining, and preserving architectural metal fea-tures from the restoration period such as columns, capitals,window hoods, or stairways; and their finishes and colors.Identification is also critical to differentiate between metalsprior to work. Each metal has unique properties and thusrequires different treatments.

Protecting and maintaining restoration period architecturalmetals from corrosion by providing proper drainage so thatwater does not stand on flat, horizontal surfaces or accumu-late in curved, decorative features.

Cleaning architectural metals, when appropriate, to removecorrosion prior to repainting or applying other appropriateprotective coatings.

Identifying the particular type of metal prior to any cleaningprocedure and then testing to assure that the gentlest cleaningmethod possible is selected or determining that cleaning isinappropriate for the particular metal.

Cleaning soft metals such as lead, tin, copper, terneplate, andzinc with appropriate chemical methods because their finishescan be easily abraded by blasting methods.

Not Recommended

Altering architectural metal features from the restoration period.

Failing to properly document architectural metal featuresfrom the restoration period which may result in their loss.

Changing the type of finish, historic color, or accent schemeunless the work can be substantiated by historical documen-tation.

Failing to identify, evaluate, and treat the causes of corrosion,such as moisture from leaking roofs or gutters.

Exposing metals which were intended to be protected fromthe environment.

Applying paint or other coatings to metals such as copper,bronze, or stainless steel that were meant to be exposed.

Using cleaning methods which alter or damage the historiccolor, texture, and finish of the metal; or cleaning when it isinappropriate for the metal.

Removing the patina of historic metal. The patina may be aprotective coating on some metals, such as bronze or copper,as well as a significant historic finish.

Cleaning soft metals such as lead, tin, copper, terneplate, andzinc with grit blasting which will abrade the surface of themetal.

Architectural Metals: Cast iron, steel pressed tin, copper, aluminum, and zinc

132 Building Exterior Metals

Restoration

Recommended

Using the gentlest cleaning methods for cast iron, wroughtiron, and steel—hard metals—in order to remove paintbuildup and corrosion. If handscraping and wire brushinghave proven ineffective, low pressure grit blasting may beused as long as it does not abrade or damage the surface.

Applying appropriate paint or other coating systems aftercleaning in order to decrease the corrosion rate of metals oralloys.


Applying an appropriate protective coating such as lacquer toan architectural metal feature such as a bronze door which issubject to heavy pedestrian use.

Evaluating the existing condition of the architectural metalsto determine whether more than protection and maintenanceare required, that is, if repairs to metal features from therestoration period will be necessary.

Repairing, stabilizing, and conserving fragile architecturalmetal from the restoration period using well-tested consoli-dants, when appropriate. Repairs should be physically andvisually compatible and identifiable upon close inspection forfuture research.

Repairing architectural metal features from the restorationperiod by patching, splicing, or otherwise reinforcing themetal using recognized preservation methods. Repairs mayalso include the limited replacement in kind—or with a com-patible substitute material—of those extensively deterioratedor missing parts of features from the restoration period whenthere are surviving prototypes such as porch balusters, col-umn capitals or bases; or porch cresting. The new workshould be unobtrusively dated to guide future research andtreatment.

Not Recommended

Failing to employ gentler methods prior to abrasively clean-ing cast iron, wrought iron or steel; or using high pressure gritblasting.

Failing to re-apply protective coating systems to metals oralloys that require them after cleaning so that accelerated corrosion occurs.

Using new colors that are not documented to the restorationperiod of the building.

Failing to assess pedestrian use or new access patterns so thatarchitectural metal features are subject to damage by use orinappropriate maintenance such as salting adjacent sidewalks.

Failing to undertake adequate measures to assure the protec-tion of architectural metal features from the restorationperiod.

Removing architectural metal from the restoration periodthat could be stabilized and conserved; or using untested con-solidants and untrained personnel, thus causing further dam-age to fragile historic materials.

Replacing an entire architectural metal feature from therestoration period such as a column or a balustrade whenrepair of the metal and limited replacement of deteriorated or missing parts are appropriate.

Using a substitute material for the replacement part that doesnot convey the visual appearance of the surviving parts of thearchitectural metal feature or that is physically or chemicallyincompatible.

Building Exterior Metals 133

Restoration

Recommended

Replacing in kind an entire architectural metal feature fromthe restoration period that is too deteriorated to repair—ifthe overall form and detailing are still evident—using thephysical evidence as a model to reproduce the feature.Examples could include cast iron porch steps or roof cresting.If using the same kind of material is not technically or eco-nomically feasible, then a compatible substitute material maybe considered. The new work should be unobtrusively datedto guide future research and treatment.

Not Recommended

Removing an architectural metal feature from the restorationperiod that is unrepairable and not replacing it.

The Standards for Restoration call for the repair of existing featuresfrom the restoration period as well as the re-creation of missing featuresfrom the period. In some instances, when missing features are replaced,substitute materials may be considered if they convey the appearance ofthe historic materials. In this example at Philadelphia’s IndependenceHall, the clock was re-built in 1972-73 using cast stone and woodwith fiberglass and polyester bronze ornamentation. Photo: Lee H.Nelson, FAIA.

134 Building Exterior Metals

Restoration

Recommended


Removing or altering architectural metal features from otherhistoric periods such as a later cast iron porch railing or alu-minum windows.

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


Re-creating a missing architectural metal feature that existedduring the restoration period based on physical or documen-tary evidence; for example, duplicating a cast iron storefrontor porch.

Not Recommended

Failing to remove an architectural metal feature from anotherperiod, thus confusing the depiction of the building’s signifi-cance.

Failing to document architectural metal features from otherhistoric periods that are removed from the building so that avaluable portion of the historic record is lost.

Constructing an architectural metal feature that was part ofthe original design for the building but was never actuallybuilt; or constructing a feature which was thought to haveexisted during the restoration period, but for which there isinsufficient documentation.

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

Building Exterior Roofs 135

Restoration

Building ExteriorRoofs

Recommended

Identifying, retaining, and preserving roofs and roof featuresfrom the restoration period. This includes the roof ’s shape,such as hipped, gambrel, and mansard; decorative featuressuch as cupolas, cresting, chimneys, and weathervanes; androofing material such as slate, wood, clay tile, and metal, aswell as size, color, and patterning.

Protecting and maintaining a restoration period roof bycleaning the gutters and downspouts and replacing deterio-rated flashing. Roof sheathing should also be checked forproper venting to prevent moisture condensation and waterpenetration; and to insure that materials are free from insectinfestation.

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

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

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

Repairing a roof from the restoration period by reinforcingthe materials which comprise roof features. Repairs will alsogenerally include the limited replacement in kind—or withcompatible substitute material—of those extensively deterio-rated or missing parts of features when there are survivingprototypes such as cupola louvers, dentils, dormer roofing; orslates, tiles, or wood shingles. The new work should beunobtrusively dated to guide future research and treatment.

Not Recommended

Altering roofs and roof features from the restoration period.

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

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

Failing to clean and maintain gutters and downspouts prop-erly so that water and debris collect and cause damage to rooffasteners, sheathing, and the underlying structure.

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

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

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

Replacing an entire roof feature from the restoration periodsuch as a cupola or dormer when the repair of materials andlimited replacement of deteriorated or missing parts areappropriate.

Failing to reuse intact slate or tile when only the roofing sub-strate needs replacement.

Using a substitute material for the replacement part that doesnot convey the visual appearance of the surviving parts of theroof or that is physically or chemically incompatible.

136 Building Exterior Roofs

Restoration

Recommended

Replacing in kind an entire roof feature from the restorationperiod that is too deteriorated to repair—if the overall formand detailing are still evident—using the physical evidence asa model to reproduce the feature. Examples can include alarge section of roofing, or a dormer or chimney. If using thesame kind of material is not technically or economically feasi-ble, then a compatible substitute material may be considered.The new work should be unobtrusively dated to guide futureresearch and treatment.

Recommended


Removing or altering roofs or roof features from other his-toric 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, select-ed examples of these features or materials should be stored tofacilitate future research.


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

Not Recommended

Removing a roof feature from the restoration period that isunrepairable, and not replacing it; or failing to document thenew work.

Not Recommended

Failing to remove a roof feature from another period, thusconfusing the depiction and of the building’s significance.

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

Constructing a roof feature that was part of the originaldesign for the building, but was never actually built; or con-structing a feature which was thought to have existed duringthe restoration period, but for which there is insufficient documentation.

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

Building Exterior Windows 137

Restoration

Building ExteriorWindows

Recommended

Identifying, retaining, and preserving windows—and theirfunctional and decorative features—from the restoration period. Such features can include frames, sash, muntins, glazing, sills, heads, hoodmolds, panelled or decorated jambsand moldings, and interior and exterior shutters and blinds.

Conducting an indepth survey of the condition of existingwindows from the restoration period early in the planningprocess so that repair and upgrading methods and possiblereplacement options can be fully explored.

Protecting and maintaining the wood and architectural metals from the restoration period which comprise the win-dow frame, sash, muntins, and surrounds through appropri-ate surface treatments such as cleaning, rust removal, limitedpaint removal, and re-application of protective coating systems.

Making windows weathertight by re-caulking, and replacingor installing weatherstripping. These actions also improvethermal efficiency.

Evaluating the existing condition of materials to determinewhether more than protection and maintenance are required,i.e. if repairs to windows and window features will berequired.

Not Recommended

Altering windows or window features from the restorationperiod.

Failing to properly document window features from therestoration period which may result in their loss.

Applying paint or other coatings to window features orremoving them if such treatments cannot be documented tothe restoration period.

Changing the type or color of protective surface coatings onwindow features unless the work can be substantiated by his-torical documentation.

Stripping windows of sound material such as wood, cast iron,and bronze.

Replacing windows from the restoration period solely becauseof peeling paint, broken glass, stuck sash, and high air infil-tration. These conditions, in themselves, are no indicationthat windows are beyond repair.

Failing to provide adequate protection of materials on a cycli-cal basis so that deterioration of the window results.

Retrofitting or replacing windows from the restoration periodrather than maintaining the sash, frame, and glazing.

Failing to undertake adequate measures to assure the protec-tion of window materials from the restoration period.

138 Building Exterior Windows

Restoration

Recommended

Repairing window frames and sash from the restoration period by patching, splicing, consolidating or otherwise rein-forcing. Such repair may also include replacement in kind—or with compatible substitute material—of those extensivelydeteriorated or missing parts when there are surviving proto-types such as architraves, hoodmolds, sash, sills, and interioror exterior shutters and blinds. The new work should beunobtrusively dated to guide future research and treatment.

Replacing in kind a window feature from the restoration period that is too deteriorated to repair using the same sashand pane configuration and other design details. If using thesame kind of material is not technically or economically feasi-ble when replacing windows deteriorated beyond repair, thena compatible substitute material may be considered. Thenew work should be unobtrusively dated to guide futureresearch and treatment.

Not Recommended

Replacing an entire window from the restoration periodwhen repair of materials and limited replacement of deterio-rated or missing parts are appropriate.

Failing to reuse serviceable window hardware such as brasssash lifts and sash locks.

Using a substitute material for the replacement part that doesnot convey the visual appearance of the surviving parts of thewindow or that is physically or chemically incompatible.

Removing a window feature from the restoration period thatis unrepairable and not replacing it; or failing to documentthe new work.

Building Exterior Windows 139

Restoration

Recommended


Removing or altering windows or window features fromother historic periods, such as later single-pane glazing orinappropriate shutters.

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


Re-creating a missing window or window feature that existedduring the restoration period based on physical or documen-tary evidence; for example, duplicating a hoodmold or shutter.

Not Recommended

Failing to remove a window feature from another period,thus confusing the depiction of the building’s significance.

Failing to document window features from other historicperiods that are removed from the building so that a valuableportion of the historic record is lost.

Constructing a window feature that was part of the originaldesign for the building, but was never actually built; or con-structing a feature which was thought to have existed duringthe restoration period, but for which there is insufficient documentation.

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

140 Building Exterior Entrances and Porches

Restoration

Building ExteriorEntrances and Porches

Recommended

Identifying, retaining, and preserving entrances and porchesfrom the restoration period—and their functional and deco-rative features—such as doors, fanlights, sidelights, pilasters,entablatures, columns, balustrades, and stairs.

Protecting and maintaining the masonry, wood, and archi-tectural metals that comprise restoration period entrances andporches through appropriate surface treatments such as clean-ing, rust removal, limited paint removal, and re-applicationof protective coating systems.

Evaluating the existing condition of materials to determinewhether more than protection and maintenance are required,that is, if repairs to entrance and porch features will be necessary.

Not Recommended

Altering entrances and porch features from the restorationperiod.

Failing to properly document entrance and porch featuresfrom the restoration period which may result in their loss

Applying paint or other coatings to entrance and porch fea-tures or removing them if such treatments cannot be docu-mented to the restoration period.

Changing the type or color of protective surface coatings onentrance and porch features unless the work can be substanti-ated by historical documentation.

Stripping entrances and porches of sound material such aswood, iron, cast iron, terra cotta, tile and brick.

Failing to provide adequate protection to materials on a cycli-cal basis so that deterioration of entrances and porches results.

Failing to undertake adequate measures to assure the protec-tion of historic entrances and porches from the restorationperiod.

Building Exterior Entrances and Porches 141

Restoration

Recommended

Repairing entrances and porches from the restoration periodby reinforcing the historic materials. Repairs will also gener-ally include the limited replacement in kind—or with com-patible substitute material—of those extensively deterioratedor missing parts of repeated features where there are survivingprototypes such as balustrades, cornices, entablatures,columns, sidelights, and stairs. The new work should beunobtrusively dated to guide future research and treatment.

Replacing in kind an entire entrance or porch from therestoration period that is too deteriorated to repair—if theform and detailing are still evident—using the physical evi-dence as a model to reproduce the feature. If using the samekind 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 futureresearch and treatment.

Not Recommended

Replacing an entire entrance or porch feature from therestoration period when the repair of materials and limitedreplacement of parts are appropriate.

Using a substitute material for the replacement part that doesnot convey the visual appearance of the surviving parts of theentrance and porch or that is physically or chemically incom-patible.

Removing an entrance or porch feature from the restorationperiod that is unrepairable and not replacing it; or failing todocument the new work.

Portions of the small porch on an Italianate mansion were carefullynumbered prior to Restoration. Some original elements were restoredin place, while others had to be removed for repair, then reinstalled.Any element too deteriorated to save was replaced with a new onereplicated to match the original design. Photo: Morgan W. Phillips.

142 Building Exterior Entrances and Porches

Restoration

Recommended


Removing or altering entrances and porches and their fea-tures from other historic periods such as a later porch railingor balustrade.



Re-creating a missing entrance or porch or its features thatexisted during the restoration period based on physical ordocumentary evidence; for example, duplicating a fanlight or porch column.

Not Recommended

Failing to remove an entrance or porch feature from anotherperiod, thus confusing the depiction of the building’s significance.

Failing to document entrance or porch features from otherhistoric periods that are removed from the building so thata valuable portion of the historic record is lost.

Constructing an entrance or porch feature that was part ofthe original design for the building but was never actuallybuilt; or constructing a feature which was thought to haveexisted during the restoration period, but for which there isinsufficient documentation.

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

Building Exterior Storefronts 143

Restoration

Building ExteriorStorefronts

Recommended

Identifying, retaining, and preserving storefronts from therestoration period—and their functional and decorative features—such as display windows, signs, doors, transoms,kick plates, corner posts, and entablatures.

Protecting and maintaining masonry, wood, and architec-tural metals which comprise restoration period storefrontsthrough appropriate treatments such as cleaning, rustremoval, limited paint removal, and reapplication of protec-tive coating systems.

Protecting storefronts against arson and vandalism beforerestoration work begins by boarding up windows andinstalling alarm systems that are keyed into local protectionagencies.

Evaluating the existing condition of storefront materials todetermine whether more than protection and maintenanceare required, that is, if repairs to features will be necessary.

Not Recommended

Altering storefronts—and their features—from the restora-tion period.

Failing to properly document storefront features from therestoration period which may result in their loss.

Applying paint or other coatings to storefront features orremoving them if such treatments cannot be documented tothe restoration period.

Changing the type or color of protective surface coatings onstorefront features unless the work can be substantiated byhistorical documentation.

Failing to provide adequate protection of materials on a cycli-cal basis so that deterioration of storefront features results.

Permitting entry into the building through unsecured or bro-ken windows and doors so that interior features and finishesare damaged by exposure to weather or vandalism.

Stripping storefronts of historic material from the restorationperiod such as wood, cast iron, terra cotta, carrara glass, andbrick.

Failing to undertake adequate measures to assure the protec-tion of storefront materials from the restoration period.

144 Building Exterior Storefronts

Restoration

Recommended

Repairing storefronts from the restoration period by reinforcingthe historic materials. Repairs will also generally include thelimited replacement in kind—or with compatible substitutematerials—of those extensively deteriorated or missing parts of storefronts where there are surviving prototypes such as tran-soms, kick plates, pilasters, or signs. The new work should beunobtrusively dated to guide future research and treatment.

Replacing in kind a storefront from the restoration period thatis too deteriorated to repair—if the overall form and detailingare still evident—using the physical evidence as a model. Ifusing the same material is not technically or economically feasi-ble, then compatible substitute materials may be considered.The new work should be unobtrusively dated to guide futureresearch and treatment.

Recommended


Removing or altering storefronts and their features from otherhistoric periods such as inappropriate cladding or signage.

Documenting materials and features dating from other periodsprior to their alteration or removal. If possible, selected exam-ples of these features or materials should be stored to facilitatefuture research.


Re-creating a missing storefront or storefront feature that exist-ed during the restoration period based on physical or documen-tary evidence; for example, duplicating a display window ortransom.

Not Recommended

Replacing an entire storefront feature from the restorationperiod when repair of materials and limited replacement of itsparts are appropriate.

Using substitute material for the replacement part that doesnot convey the same visual appearance as the surviving partsof the storefront or that is physically or chemically incompati-ble.

Removing a storefront feature from the restoration periodthat is unrepairable, and not replacing it; or failing to docu-ment the new work.

Not Recommended

Failing to remove a storefront feature from another period,thus confusing the depiction of the building’s significance.

Failing to document storefront features from other historicperiods that are removed from the building so that a valuableportion of the historic record is lost.

Constructing a storefront feature that was part of the originaldesign for the building but was never actually built; or con-structing a feature which was thought to have existed duringthe restoration period, but for which there is insufficient doc-umentation.

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

Building Interior Structural Systems 145

Restoration

Building InteriorStructural Systems

Recommended

Identifying, retaining, and preserving structural systems fromthe restoration period—and individual features of systems—such as post and beam systems, trusses, summer beams, vigas,cast iron columns, above-grade stone foundation walls, orloadbearing brick or stone walls.

Protecting and maintaining the structural system by cleaningthe roof gutters and downspouts; replacing roof flashing;keeping masonry, wood, and architectural metals in a soundcondition; and ensuring that structural members are freefrom insect infestation.

Examining and evaluating the physical condition of the struc-tural system and its individual features using non-destructivetechniques such as X-ray photography.

Repairing the structural system by augmenting or upgradingindividual parts or features in a manner that is consistentwith the restoration period. For example, weakened structur-al members such as floor framing can be paired with a newmember, braced, or otherwise supplemented and reinforced.The new work should be unobtrusively dated to guide futureresearch and treatment.

Not Recommended

Altering visible features of structural systems from the restora-tion period.

Failing to properly document structural systems from therestoration period which may result in their loss.

Overloading the existing structural system; or installingequipment or mechanical systems which could damage thestructure.

Replacing a loadbearing masonry wall that could be aug-mented and retained.

Leaving known structural problems untreated such as deflec-tion of beams, cracking and bowing of walls, or racking ofstructural members.

Failing to provide proper building maintenance so that dete-rioration of the structural system results. Causes of deteriora-tion include subsurface ground movement, vegetation grow-ing too close to foundation walls, improper grading, fungalrot, and poor interior ventilation that results in condensation.

Utilizing destructive probing techniques that will damage ordestroy structural material.

Upgrading the building structurally in a manner that dimin-ishes the historic character of the exterior, such as installingstrapping channels or removing a decorative cornice; or thatdamages interior features or spaces.

Replacing a structural member or other feature of the struc-tural system when it could be augmented and retained.

146 Building Interior Structural Systems

Restoration

Recommended

Replacing in kind—or with substitute material—those por-tions or features of the structural system that are either exten-sively deteriorated or are missing when there are survivingprototypes such as cast iron columns, roof rafters or trusses,or sections of loadbearing walls. Substitute material shouldconvey the same form, design, and overall visual appearanceas the historic feature; and, at a minimum, be equal to itsloadbearing capabilities. The new work should be unobtru-sively dated to guide future research and treatment.

Recommended


Removing or altering visually intrusive structural featuresfrom other historic periods such as a non-matching columnor exposed ceiling beams.



Re-creating a missing structural feature that existed duringthe restoration period based on physical or documentary evi-dence; for example, duplicating a viga or cast iron column.

Not Recommended

Installing a visible replacement feature that does not conveythe same visual appearance, e.g., replacing an exposed woodsummer beam with a steel beam; or failing to document thenew work.

Using substitute material that does not equal the loadbearingcapabilities of the historic material and design or is otherwisephysically or chemically incompatible.

Not Recommended

Failing to remove or alter a visually intrusive structural featurefrom another period, thus confusing the depiction of thebuilding’s significance.

Failing to document structural features from other historicperiods that are removed from the building so that a valuableportion of the historic record is lost.

Constructing a structural feature that was part of the originaldesign for the building but was never actually built; or con-structing a feature which was thought to have existed duringthe restoration period, but for which there is insufficient doc-umentation.

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

Building Interior Spaces, Features, and Finishes 147

Restoration

Building Interior Spaces, Features, and Finishes

Recommended

Interior Spaces

Identifying, retaining, and preserving a floor plan or interiorspaces from the restoration period. This includes the size,configuration, proportion, and relationship of rooms andcorridors; the relationship of features to spaces; and the spacesthemselves, such as lobbies, reception halls, entrance halls,double parlors, theaters, auditoriums, and important indus-trial or commercial spaces.

Interior Features and Finishes

Identifying, retaining, and preserving interior features andfinishes from the restoration period. These include columns,cornices, baseboards, fireplaces and mantels, panelling, lightfixtures, hardware, and flooring; and wallpaper, plaster, paint,and finishes such as stencilling, marbling, and graining; andother decorative materials that accent interior features andprovide color, texture, and patterning to walls, floors, andceilings.

Protecting and maintaining masonry, wood, and architec-tural metals that comprise restoration period interior featuresthrough appropriate surface treatments such as cleaning, rustremoval, limited paint removal, and reapplication of protec-tive coating systems.

Not Recommended

Altering a floor plan or interior spaces—including individualrooms—from the restoration period.

Altering features or finishes from the restoration period.

Failing to properly document spaces, features, and finishesfrom the restoration period which may result in their loss.

Applying paint, plaster, or other finishes to surfaces unless thework can be substantiated historical documentation.

Stripping paint to bare wood rather than repairing or reapply-ing grained or marbled finishes from the restoration period tofeatures such as doors and panelling.

Changing the type of finish or its color, such as painting apreviously varnished wood feature, unless the work can besubstantiated by historical documentation.

Failing to provide adequate protection to materials on a cycli-cal basis so that deterioration of interior features results.

148 Building Interior Spaces, Features, and Finishes

Restoration

Recommended

Protecting interior spaces, features and finishes against arsonand vandalism before project work begins, erecting protectivefencing, boarding-up windows, and installing fire alarm sys-tems that are keyed to local protection agencies.

Protecting interior features such as a staircase, mantel, or dec-orative finishes and wall coverings against damage duringproject work by covering them with heavy canvas or plasticsheets.

Installing protective coverings in areas of heavy pedestriantraffic to protect historic features such as wall coverings, parquet flooring and panelling.

Removing damaged or deteriorated paints and finishes to the next sound layer using the gentlest method possible, then repainting or refinishing using compatible paint or other coating systems based on historical documentation.

Repainting with colors that are documented to the building’srestoration period.

Limiting abrasive cleaning methods to certain industrialwarehouse buildings where the interior masonry or plasterfeatures do not have distinguishing design, detailing, tooling,or finishes; and where wood features are not finished, molded, beaded, or worked by hand. Abrasive cleaningshould only be considered after other, gentler methods havebeen proven ineffective.

Evaluating the existing condition of materials to determinewhether more than protection and maintenance are required,that is, if repairs to interior features and finishes will be neces-sary.

Not Recommended

Permitting entry into historic buildings through unsecured orbroken windows and doors so that the interior features andfinishes are damaged by exposure to weather or vandalism.

Stripping interiors of restoration period features such aswoodwork, doors, windows, light fixtures, copper piping,radiators; or of decorative materials.

Failing to provide proper protection of interior features andfinishes during work so that they are gouged, scratched, dented, or otherwise damaged.

Failing to take new use patterns into consideration so thatinterior features and finishes are damaged.

Using destructive methods such as propane or butane torchesor sandblasting to remove paint or other coatings. Thesemethods can irreversibly damage the historic materials thatcomprise interior features.

Using new paint colors that are inappropriate to thebuilding’s restoration period.

Changing the texture and patina of features from the restora-tion period through sandblasting or use of abrasive methodsto remove paint, discoloration or plaster. This includes bothexposed wood (including structural members) and masonry.

Failing to undertake adequate measures to assure the protec-tion of interior features and finishes.

Building Interior Spaces, Features, and Finishes 149

Restoration

Recommended

Repairing interior features and finishes from the restorationperiod by reinforcing the historic materials. Repair will alsogenerally include the limited replacement in kind—or withcompatible substitute material—of those extensively deterio-rated or missing parts of repeated features when there are sur-viving prototypes such as stairs, balustrades, wood panelling,columns; or decorative wall coverings or ornamental tin orplaster ceilings. The new work should be unobtrusively datedto guide future research and treatment.

Replacing in kind an entire interior feature or finish from therestoration period that is too deteriorated to repair—if theoverall form and detailing are still evident—using the physi-cal evidence as a model for reproduction. Examples couldinclude wainscoting, a tin ceiling, or interior stairs. If usingthe same kind of material is not technically or economicallyfeasible, then a compatible substitute material may be consid-ered. The new work should be unobtrusively dated to guidefuture research and treatment.

Not Recommended

Replacing an interior feature from the restoration period suchas a staircase, panelled wall, parquet floor, or cornice; or finishsuch as a decorative wall covering or ceiling when repair ofmaterials and limited replacement of such parts are appro-priate.

Using a substitute material for the replacement part that doesnot convey the visual appearance of the surviving parts orportions of the interior feature or finish or that is physicallyor chemically incompatible.

Removing a feature or finish from the restoration period thatis unrepairable and not replacing it; or failing to documentthe new work.

A complete paint investigation often needs to be conducted during Restoration. Paint samples are carefully collected onsite. In the laboratory, an ultra violet light is used to identify pigment and binding media. Paint samples are then photographed.Physical evidence documented through laboratory research provides a sound basis for an accurate restoration of painted finishes, such as the complex stencilling pictured here. Photo left: Courtesy, Alexis Elza; Photo right: Courtesy, Andrea Gilmore.

150 Building Interior Spaces, Features, and Finishes

Restoration

Recommended


Removing or altering interior spaces, features and finishesfrom other historic periods such as a later suspended ceilingor wood panelling.

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


Re-creating an interior space, or a missing feature or finishfrom the restoration period based on physical or documen-tary evidence; for example, duplicating a marbleized mantelor a staircase.

Not Recommended

Failing to remove or alter an interior space, feature, or finishfrom another period, thus confusing the depiction of thebuilding’s significance.

Failing to document interior spaces, features, and finishesfrom other historic periods that are removed from the build-ing so that a valuable portion of the historic record is lost.

Constructing an interior space, feature, or finish that was partof the original design for the building but was never actuallybuilt; or constructing a feature which was thought to haveexisted during the restoration period, but for which there isinsufficient documentation.

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

The missing plaster cornicewas restored as part of anoverall project to return a res-idence to its original appear-ance. The traditionalmethod of producing a cor-nice is unchanged today.Photo: Old-House Journal.

Building Interior Mechanical Systems 151

Restoration

Building Interior

Recommended

Identifying, retaining, and preserving visible features ofmechanical systems from the restoration period such as radia-tors, vents, fans, grilles, plumbing fixtures, switchplates, andlights.

Protecting and maintaining mechanical, plumbing, and elec-trical systems and their features from the restoration periodthrough cyclical cleaning and other appropriate measures.

Preventing accelerated deterioration of mechanical systems byproviding adequate ventilation of attics, crawlspaces, and cel-lars so that moisture problems are avoided.

Improving the energy efficiency of existing mechanical sys-tems to help reduce the need for elaborate new equipment.

Repairing mechanical systems from the restoration period byaugmenting or upgrading system parts, such as installing newpipes and ducts; rewiring; or adding new compressors or boilers.

Replacing in kind—or with compatible substitute material—those visible features of restoration period mechanical systemsthat are either extensively deteriorated or are prototypes suchas ceiling fans, switchplates, radiators, grilles, or plumbingfixtures.

Installing a new mechanical system, if required, in a way thatresults in the least alteration possible to the building.

Not Recommended

Altering visible decorative features of mechanical systemsfrom the restoration period.

Failing to properly document mechanical systems and theirvisible decorative features from the restoration period whichmay result in their loss.

Failing to provide adequate protection of materials on a cycli-cal basis so that deterioration of mechanical systems and theirvisible features results.

Enclosing mechanical systems in areas that are not adequatelyventilated so that deterioration of the systems results.

Installing unnecessary air conditioning or climate control sys-tems which can add excessive moisture to the building. Thisadditional moisture can either condense inside, damaginginterior surfaces, or pass through interior walls to the exterior,potentially damaging adjacent materials as it migrates.

Replacing a mechanical system from the restoration period orits functional parts when it could be upgraded and retained.

Installing a visible replacement feature that does not conveythe same visual appearance.

Installing a new mechanical system so that structural or interior features from the restoration period are altered.

Mechanical Systems: Heating, Air Conditioning, Electrical, and Plumbing

152 Building Interior Mechanical Systems

Restoration

Recommended

Providing adequate structural support for new mechanicalequipment.

Installing the vertical runs of ducts, pipes, and cables in clos-ets, service rooms, and wall cavities.

Installing air conditioning units in such a manner that fea-tures are not damaged or obscured and excessive moisture isnot generated that will accelerate deterioration of historicmaterials.

Recommended


Removing or altering mechanical systems and features fromother historic periods such as a later elevator or plumbing fixture.



Re-creating a missing feature of the mechanical system thatexisted during the restoration period based on physical ordocumentary evidence; for example, duplicating a heatingvent or gaslight fixture.

Not Recommended

Failing to consider the weight and design of new mechanicalequipment so that, as a result, historic structural members orfinished surfaces are weakened or cracked.

Installing vertical runs of ducts, pipes, and cables in placeswhere they will obscure features from the restoration period.

Concealing mechanical equipment in walls or ceilings in amanner that requires the removal of building material fromthe restoration period.

Cutting through features such as masonry walls in order toinstall air conditioning units.

Not Recommended

Failing to remove a mechanical system or feature from another period, thus confusing the depiction of the building’ssignificance.

Failing to document mechanical systems and features fromother historic periods that are removed from the building sothat a valuable portion of the historic record is lost.

Constructing a mechanical system or feature that was part ofthe original design for the building but was never actuallybuilt; or constructing a feature which was thought to haveexisted during the restoration period, but for which there isinsufficient documentation.

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

Building Site 153

Restoration

Building Site

Recommended

Identifying, retaining, and preserving restoration periodbuildings and their features as well as features of the site. Sitefeatures may include circulation systems such as walks, paths,roads, or parking; vegetation such as trees, shrubs, fields, orherbaceous plant material; landforms such as terracing, bermsor grading; furnishings such as lights, fences, or benches; dec-orative elements such as sculpture, statuary or monuments;water features including fountains, streams, pools, or lakes;and subsurface archeological features which are important indefining the restoration period.

Not Recommended

Altering buildings and their features or site features from therestoration period.

Failing to properly document building and site features fromthe restoration period which may result in their loss.

This ca. 1900 photograph (left) would be invaluable to guide restoration of the deteriorated house (right) to its documented earlier appearance, complete with decorative trim, shutters, polychromed exterior, and fencing. Photos: Courtesy, North Carolina Department of Archives and History.

154 Building Site

Restoration

Recommended

Re-establishing the relationship between buildings and thelandscape that existed during the restoration period.

Protecting and maintaining buildings and the site by provid-ing proper drainage to assure that water does not erode foun-dation walls; drain toward the building; or damage or erodethe landscape.

Minimizing disturbance of terrain around buildings or else-where on the site, thus reducing the possibility of destroyingor damaging important landscape features or archeologicalresources.

Surveying and documenting areas where the terrain will bealtered during restoration work to determine the potentialimpact to landscape features or archeological resources.

Protecting, e.g., preserving in place, important archeologicalresources.

Planning and carrying out any necessary investigation usingprofessional archeologists and modern archeological methodswhen preservation in place is not feasible.

Preserving important landscape features from the restorationperiod, including ongoing maintenance of historic plantmaterial.

Protecting building and landscape features against arson andvandalism before restoration work begins, i.e., erecting pro-tective fencing and installing alarm systems that are keyedinto local protection agencies.

Not Recommended

Retaining non-restoration period buildings or landscape features.

Failing to maintain adequate site drainage so that buildingsand site features are damaged or destroyed; or alternatively,changing the site grading so that water no longer drainsproperly.

Introducing heavy machinery into areas where it may disturbor damage important landscape features or archeologicalresources.

Failing to survey the building site prior to beginning restora-tion work which results in damage to, or destruction of, land-scape features or archeological resources.

Leaving known archeological material unprotected so that itis damaged during restoration work.

Permitting unqualified personnel to perform data recovery onarcheological resources so that improper methodology resultsin the loss of important archeological material.

Allowing restoration period landscape features to be lost ordamaged due to a lack of maintenance.

Permitting the property to remain unprotected so that thebuilding and landscape features or archeological resources aredamaged or destroyed.

Removing restoration period features from the building orsite such as wood siding, iron fencing, masonry balustrades,or plant material.

Building Site 155

Restoration

Recommended

Providing continued protection of building materials andplant features from the restoration period through appropri-ate cleaning, rust removal, limited paint removal, and re-application of protective coating systems; and pruning andvegetation management.

Evaluating the existing condition of materials and features todetermine whether more than protection and maintenanceare required, that is, if repairs to building and site features willbe necessary.

Repairing restoration period features of the building and siteby reinforcing historic materials. The new work should beunobtrusively dated to guide future research and treatment.

Replacing in kind an entire restoration period feature of thebuilding or site that is too deteriorated to repair if the overallform and detailing are still evident. Physical evidence fromthe deteriorated feature should be used as a model to guidethe new work. This could include an entrance or porch,walkway, or fountain. If using the same kind of material isnot technically or economically feasible, then a compatiblesubstitute material may be considered. The new work shouldbe unobtrusively dated to guide future research and treat-ment.

Replacing deteriorated or damaged landscape features of therestoration period in kind or with compatible substitutematerial. The replacement feature should be based on physi-cal evidence and convey the same appearance.

Not Recommended

Failing to provide adequate protection of materials on a cyclical basis so that deterioration of building and site features results.

Failing to undertake adequate measures to assure the protec-tion of building and site features.

Replacing an entire restoration period feature of the buildingor site such as a fence, walkway, or driveway when repair ofmaterials and limited compatible replacement of deterioratedor missing parts are appropriate.

Using a substitute material for the replacement part that doesnot convey the visual appearance of the surviving parts of thebuilding or site feature or that is physically or chemicallyincompatible.

Removing a restoration period feature of the building or sitethat is unrepairable and not replacing it; or failing to docu-ment the new work.

Adding conjectural landscape features to the site such asperiod reproduction lamps, fences, fountains, or vegetationthat are historically inappropriate, thus creating an inaccuratedepiction of the restoration period.

156 Building Site

Restoration

Recommended


Removing or altering features of the building or site fromother historic periods such as a later outbuilding, paved road,or overgrown tree.

Documenting features of the building or site from other periods prior to their alteration or removal.


Re-creating a missing feature of the building or site that existed during the restoration period based on physical ordocumentary evidence; for example, duplicating a terrace,gazebo, or fencing.

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

Not Recommended

Failing to remove a feature of the building or site from anoth-er period, thus creating an inaccurate historic appearance.

Failing to document features of the building or site fromother historic periods that are removed during restoration sothat a valuable portion of the historic record is lost.

Constructing a feature of the building or site that was part ofthe original design, but was never actually built; or construct-ing a feature which was thought to have existed during therestoration period, but for which there is insufficient docu-mentation.

Setting 157

Restoration

Setting (District/Neighborhood)

Recommended

Identifying retaining, and preserving restoration periodbuilding and landscape features of the setting. Such featurescan include roads and streets, furnishings such as lights orbenches, vegetation, gardens and yards, adjacent open spacesuch as fields, parks, commons or woodlands, and importantviews or visual relationships.

Re-establishing the relationship between buildings and land-scape features of the setting that existed during the restorationperiod.

Protecting and maintaining building materials and plant features from the restoration period through appropriatecleaning, rust removal, limited paint removal, and reapplica-tion of protective coating systems; and pruning and vegeta-tion management.

Protecting buildings and landscape features against arson andvandalism before restoration work begins by erecting protec-tive fencing and installing alarm systems that are keyed intolocal protection agencies.

Evaluating the existing condition of the building and land-scape features to determine whether more than protectionand maintenance are required, that is, if repairs to featureswill be necessary.

Repairing restoration period features of the building andlandscape by reinforcing the historic materials. Repair willgenerally include the replacement in kind—or with compati-ble substitute material—of those extensively deteriorated ormissing parts of features where there are surviving prototypessuch as porch balustrades or paving materials. The new workshould be unobtrusively dated to guide future research andtreatment.

Not Recommended

Altering features of the setting that can be documented to therestoration period.

Failing to properly document restoration period building andlandscape features, which may result in their loss.

Retaining non-restoration period buildings or landscape features.

Failing to provide adequate protection of materials on a cyclical basis which results in the deterioration of buildingand landscape features.

Permitting the building and setting to remain unprotected sothat interior or exterior features are damaged.

Stripping or removing features from buildings or the settingsuch as wood siding, iron fencing, terra cotta balusters, orplant material.

Failing to undertake adequate measures to assure the protec-tion of building and landscape features.

Replacing an entire restoration period feature of the buildingor landscape setting when repair of materials and limitedreplacement of deteriorated or missing parts are appropriate.

Using a substitute material for the replacement part that doesnot convey the visual appearance of the surviving parts of thebuilding or landscape, or that is physically, chemically, or eco-logically incompatible.

158 Setting

Restoration

Recommended

Replacing in kind an entire restoration period feature of thebuilding or landscape that is too deteriorated to repair—when the overall form and detailing are still evident—usingthe physical evidence as a model to guide the new work. Ifusing the same kind of material is not technically or econom-ically feasible, then a compatible substitute material may beconsidered. The new work should be unobtrusively dated toguide future research and treatment.

Recommended


Removing or altering features of the building or landscapefrom other historic periods, such as a later road, sidewalk, orfence.

Documenting features of the building or landscape datingfrom other periods prior to their alteration or removal.


Re-creating a missing feature of the building or landscape inthe setting that existed during the restoration period based onphysical or documentary evidence; for example, duplicating apath or park bench.

Not Recommended

Removing a restoration period feature of the building orlandscape that is unrepairable and not replacing it; or failingto document the new work.

Not Recommended

Failing to remove a feature of the building or landscape from another period, thus creating an inaccurate historicappearance.

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

Constructing a feature of the building or landscape that waspart of the original design for the setting but was never actu-ally built; or constructing a feature which was thought tohave existed during the restoration period, but for whichthere is insufficient documentation.

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

Setting 159

Restoration

The Bronson-MulhollandHouse in Palatka, Florida, ca.1845, is shown (a) before and(b) after the treatment,Restoration. Over the years theeast (far right) side of theveranda had been filled in as asixth bay. During the restora-tion, this later infill wasremoved and the east veranda,together with its flooring,stairs, and foundation,restored. Photo: City ofPalatka, CommunityDevelopment Department.

160 Energy Efficiency

Restoration

Energy Efficiency

Recommended

Masonry/Wood/Architectural Metals

Installing thermal insulation in attics and in unheated cellarsand crawlspaces to increase the efficiency of the existingmechanical systems.

Installing insulating material on the inside of masonry walls toincrease energy efficiency where there is no interior moldingaround the windows or other interior architectural detailingfrom the restoration period.

Windows

Utilizing the inherent energy conserving features of a buildingby maintaining windows and louvered blinds from the restora-tion period in good operable condition for natural ventilation.

Improving thermal efficiency with weatherstripping, stormwindows, caulking, interior shades, and if historically appro-priate, blinds and awnings.

Installing interior storm windows with air-tight gaskets, venti-lating holes, and/or removable clips to ensure proper mainte-nance and to avoid condensation damage to historic windows.

Installing exterior storm windows which do not damage orobscure the windows and frames.

Although the work in the following sections is quite often an important aspect of restoration projects, it is usually not part of the over-all process of preserving features from the restoration period (protection, stabilization, conservation, repair, and replacement); rather,such work is assessed for its potential negative impact on the building’s historic appearance. For this reason, particular care must betaken not to obscure, alter, or damage features from the restoration period in the process of undertaking work to meet code and ener-

Not Recommended

Applying thermal insulation with a high moisture content inwall cavities which may damage historic fabric.

Installing wall insulation without considering its effect oninterior or other architectural detailing.

Using shading devices that are inappropriate to the restora-tion period.

Replacing multi-paned sash from the restoration period withnew thermal sash utilizing false muntins.

Installing interior storm windows that allow moisture toaccumulate and damage the window.

Installing new exterior storm windows which are inappro-priate in size or color.

Replacing windows or transoms from the restoration periodwith fixed thermal glazing or permitting windows and tran-soms to remain inoperable rather than utilizing them for theirenergy conserving potential.

Energy Efficiency 161

Restoration

Recommended

Entrances and Porches

Maintaining porches and double vestibule entrances from therestoration period so that they can retain heat or block thesun and provide natural ventilation.

Interior Features

Retaining interior shutters and transoms from the restorationperiod for their inherent energy conserving features.

Mechanical Systems

Improving energy efficiency of existing mechanical systemsby installing insulation in attics and basements.

Building Site

Retaining plant materials, trees, and landscape features whichperform passive solar energy functions, such as sun shadingand wind breaks, if appropriate to the restoration period.

Setting (District/Neighborhood)

Maintaining those existing landscape features which moder-ate the effects of the climate on the setting such as deciduoustrees, evergreen wind-blocks, and lakes or ponds, if appro-priate to the restoration period.

Not Recommended

Changing porches significant to the restoration period byenclosing them.

Removing interior features from the restoration period thatplay a secondary energy conserving role.

Replacing existing mechanical systems that could be repairedfor continued use.

Removing plant materials, trees, and landscape features from the restoration period that perform passive solar energyfunctions.

Stripping the setting of landscape features and landformsfrom the restoration period so that effects of the wind, rain,and sun result in accelerated deterioration of the historicbuilding.

162 Accessibility Considerations

Restoration

Accessibility Considerations

Recommended

Identifying spaces, features, and finishes from the restorationperiod so that accessibility code-required work will not resultin their damage or loss.

Complying with barrier-free access requirements in such amanner that spaces, features, and finishes from the restora-tion period are preserved.

Working with local disability groups, access specialists, andhistoric preservation specialists to determine the most appro-priate solution to access problems.

Providing barrier-free access that promotes independence forto the highest degree practicable, while preserving significanthistoric features.

Finding solutions to meet accessibility requirements thatminimize the impact on the historic building and its site,such as compatible ramps, paths, and lifts.

Not Recommended

Undertaking code-required alterations before identifyingthose spaces, features, or finishes from the restoration periodwhich must be preserved.

Altering, damaging, or destroying features from the restora-tion period in attempting to comply with accessibilityrequirements.

Making changes to buildings without first seeking expertadvice from access specialists and historic preservationists todetermine solutions.

Making access modifications that do not provide a reasonablebalance between independent, safe access and preservation ofhistoric features.

Making modifications for accessibility without consideringthe impact on the historic building and its site.

Health and Safety Considerations 163

Restoration

Health and Safety Considerations

Recommended

Identifying spaces, features, and finishes from the restorationperiod so that code-required work will not result in theirdamage or loss.

Complying with health and safety codes, including seismiccode requirements, in such a manner that spaces, features,and finishes from the restoration period are preserved.

Removing toxic building materials only after thorough test-ing has been conducted and only after less invasive abatementmethods have been shown to be inadequate.

Providing workers with appropriate personal protectiveequipment for hazards found at the worksite.

Working with local code officials to investigate systems,methods, or devices of equivalent or superior effectivenessand safety to those prescribed by code so that unnecessaryalterations can be avoided.

Upgrading historic stairways and elevators from the restora-tion period to meet health and safety codes in a manner thatassures their preservation, i.e., so that they are not damagedor obscured.

Installing sensitively designed fire suppression systems, suchas sprinkler systems, that result in retention of features andfinishes from the restoration period.

Applying fire-retardant coatings, such as intumescent paints,which expand during fire to add thermal protection to steel.

Adding a new stairway or elevator to meet health and safetycodes in a manner that preserves adjacent features and spacesfrom the restoration period.

Not Recommended

Undertaking code-required alterations to a building or sitebefore identifying those spaces, features, or finishes from therestoration period which must be preserved.

Altering, damaging, or destroying spaces, features, and fin-ishes while making modifications to a building or site tocomply with safety codes.

Destroying interior features and finishes from the restorationperiod without careful testing and without considering lessinvasive abatement methods.

Removing unhealthful building materials without regard topersonal and environmental safety.

Making changes to historic buildings without first exploringequivalent health and safety systems, methods, or devices thatmay be less damaging to spaces, features, and finishes fromthe restoration period.

Damaging or obscuring stairways and elevators or alteringadjacent spaces from the restoration period in the process ofdoing work to meet code requirements.

Covering wood features from the restoration period with fire-resistant sheathing which results in altering their visualappearance.

Using fire-retardant coatings if they damage or obscure fea-tures from the restoration period.

Altering the appearance of spaces, features, or finishes fromthe restoration period when adding a new code-requiredstairway or elevator.

Documents

Restoration Standards and Guidelines for Historic Buildings · Restoring Historic Buildings is to make the building appear as it did at a particular—and most signifi-cant—time