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Appendix IX-B-4, Facilities Manual

The Secretary of the Interior’s Standards for Rehabilitation and Guidelinesfor Rehabilitating Historic Buildings (Revised 1983)

U.S. Department of the InteriorNational Park ServicePreservation Assistance DivisionWashington, D.C.

The “Secretary of the Interior’s Standards for HistoricPreservation Projects” were initially prepared in 1979 by W.Brown Morton III and Gary L. Hume. The updated andexpanded Guidelines for Rehabilitating Historic Buildings thatfollow were developed by Gary L. Hume and Kay D. Weeks,Technical Preservation Services, Preservation AssistanceDivision, with the assistance of the professional and supportstaff.

CONTENTS

Introduction to the Standards and Guidelines

BUILDING EXTERIOR

Masonry: Brick, stone, terra-cotta, concrete, adobe, stucco, and mortarPreservation of Historic Features (maintenance, repair, replacement)Design for Missing Historic Features

Wood: Clapboard, weatherboard, shingles, and other wooden siding and decorative elementsPreservation of Historic Features (maintenance, repair, replacement)Design for Missing Historic Features

Architectural Metals: Cast iron, steel, pressed tin, copper, aluminum, and zincPreservation of Historic Features (maintenance, repair, replacement)Design for Missing Historic Features

RoofsPreservation of Historic Features (maintenance, repair, replacement)Design for Missing Historic FeaturesAdditions/Alterations for the New Use

WindowsPreservation of Historic Features (maintenance, repair, replacement)Design for Missing Historic FeaturesAdditions/Alterations for the New Use

Entrances and PorchesPreservation of Historic Features (maintenance, repair, replacement)Design for Missing Historic Features


Additions/Alterations for the New Use

StorefrontsPreservation of Historic Features (maintenance, repair, replacement)Design for Missing Historic Features

THE SECRETARY OF THE INTERIOR’S STANDARDS FOR REHABILITATION

The Secretary of the Interior is responsible for establishing standards for all programs under Departmentalauthority and for advising Federal agencies on the preservation of historic properties listed or eligible forlisting in the National Register of Historic Places. In partial fulfillment of this responsibility, theSecretary of the Interior’s standards for Historic Preservation Projects have been developed to directwork undertaken on historic buildings.

Initially used by the Secretary of the Interior in determining the applicability of proposed project work onregistered properties within the Historic Preservation Fund grant-in-aid program, the Standards forHistoric Preservation Projects have received extensive testing over the years—more than 6,000acquisition and development projects were approved for a variety of work treatments. In addition, theStandards have been used by Federal agencies in carrying out their historic preservation responsibilitiesfor properties in Federal ownership or control; and by State and local officials in the review of bothFederal and nonfederal rehabilitation proposals. They have also been adopted by a number of historicdistrict and planning commissions across the country.

The Standards for Rehabilitation (36 CFR 67) comprise that section of the overall historic preservationproject standards addressing the most prevalent treatment today: Rehabilitation. “Rehabilitation” isdefined as the process of returning a property to a state of utility, through repair or alteration, whichmakes possible an efficient contemporary use while preserving those portions and features of theproperty which are significant to its historic, architectural, and cultural values.

The Standards for Rehabilitation are as follows:

1. Every reasonable effort shall be made to provide a compatible use for a property which requiresminimal alteration of the building, structure, or site and its environment, or to use a property for itsoriginally intended purpose.

2. The distinguishing original qualities or character of a building, structure, or site and its environmentshall not be destroyed. The removal or alteration of any historic material or distinctive architecturalfeatures should be avoided when possible.

3. All buildings, structures, and sites shall be recognized as products of their own time. Alterationsthat have no historical basis and which seek to create an earlier appearance shall be discouraged.

4. Changes which may have taken place in the course of time are evidence of the history anddevelopment of a building, structure, or site and its environment. These changes may haveacquired significance in their own right, and this significance shall be recognized and respected.


5. Distinctive stylistic features or examples of skilled craftsmanship which characterize a building,structure, or site shall be treated with sensitivity.

6. Deteriorated architectural features shall be repaired rather than replaced, wherever possible. In theevent replacement is necessary, the new material should match the material being replaced incomposition, design, color, texture, and other visual qualities. Repair or replacement of missingarchitectural features should be visual qualities. Repair or replacement of missing architecturalfeatures should be based on accurate duplications of features, substantiated by historic, physical, orpictorial evidence rather than on conjectural designs or the availability of different architecturalelements from other buildings or structures.

7. The surface cleaning of structures shall be undertaken with the gentlest means possible.Sandblasting and other cleaning methods that will damage the historic building materials shall notbe undertaken.

8. Every reasonable effort shall be made to protect and preserve archeological resources affected by,or adjacent to any project.

9. Contemporary design for alterations and additions to existing properties shall not be discouragedwhen such alterations and additions do not destroy significant historical, architectural or culturalmaterial, and such design is compatible with the size, scale, color, material, and character of theproperty, neighborhood or environment.

10. Wherever possible, new additions or alterations to structures shall be done in such a manner that ifsuch additions or alterations were to be removed in the future, the essential form and integrity of thestructure would be unimpaired.

In the past several years, the most frequent use of the Secretary’s “Standards for Rehabilitation” has beento determine if a rehabilitation project qualifies as a “certified rehabilitation” pursuant to the Tax ReformAct of 1976, the Revenue Act of 1978, and the Economic Recovery Tax Act of 1981, as amended. TheSecretary is required by law to certify rehabilitations that are “consistent with the historic character of thestructure or the district in which it is located.” The Standards are used to evaluate whether the historiccharacter of a building is preserved in the process of rehabilitation. Between 1976 and 1982 over 5,000projects were reviewed and approved under the Preservation Tax incentives program.

As stated in the definition, the treatment “Rehabilitation” assumes that at least some repair or alteration ofthe historic building will need to take place in order to provide for an efficient contemporary use;however these repairs and alterations must not damage or destroy the materials and features—includingtheir finishes—that are important in defining the building’s historic character.

In terms of specific project work, preservation of the building and its historic character is based on theassumption that (1) the historic materials and features and their unique craftsmanship are of primaryimportance and that (2), in consequence they will be retained, protected, and repaired in the process ofrehabilitation to the greatest extent possible, not removed and replaced with materials and featureswhich appear to be historic, but which are—in fact—new.

To best achieve these preservation goals, a two-part evaluation needs to be applied by qualified historicpreservation professionals for each project as follows: first, a particular property’s materials and featureswhich are important in defining its historic character should be identified. Examples may include abuilding’s walls, cornice, window sash and frames and roof; rooms, hallways, stairs, and mantels; or asite’s walkways, fences, and gardens. The second part of the evaluation should consist of assessing thepotential impact of the work necessary to make possible an efficient contemporary use. A basic


assumption in this process is that the historic character of each property is unique and therefore proposedrehabilitation work will necessarily have a different effect on each property; in other words, what may beacceptable for one project may be unacceptable for another. However, the requirement set forth in thedefinition of “Rehabilitation” is always the same for every project: those portions and features of theproperty which are significant to its historic, architectural, and cultural values must be preserved in theprocess of rehabilitation. To accomplish this, all ten of the Secretary of the Interior’s“Standards for Rehabilitation” must be met.

GUIDELINES FOR REHABILITATING HISTORIC BUILDINGS

The Guidelines were initially developed in 1977 to help property owners, developers, and Federalmanagers apply the Secretary of the Interior’s “Standards for Rehabilitation” during the project planningstage by providing general design and technical recommendations. Unlike the Standards, the Guidelinesare not codified as program requirements. Together with the “Standards for Rehabilitation” theyprovide a model process for owners, developers, and federal agency managers to follow.

It should be noted at the outset that the Guidelines are intended to assist in applying the Standards toprojects generally; consequently, they are not meant to give case-specific advice or address exceptions orrare instances. For example, they cannot tell an owner or developer which features of their own historicbuilding are important in defining the historic character and must be preserved—although examples areprovided in each section—or which features could be altered, if necessary, for the new use. This kind ofcareful case-by-case decisionmaking is best accomplished by seeking assistance from qualified historicpreservation professionals in the planning stage of the project. Such professionals include architects,architectural historians, historians, archeologists, and others who are skilled in the preservation,rehabilitation, and restoration of historic properties.

The Guidelines pertain to historic buildings of all sizes, materials, occupancy, and construction types; andapply to interior and exterior work as well as new exterior additions. Those approaches, treatments, andtechniques that are consistent with the Secretary of the Interior’s “Standards for Rehabilitation” are listedin the “Recommended” column on the left; those approaches, treatments, and techniques which couldadversely affect a building’s historic character are listed in the “Not Recommended” column on the right.

To provide clear and consistent guidance for owners, developers, and federal agency managers to follow,the “Recommended” courses of action in each section are listed in order of historic preservation concernsso that a rehabilitation project may be successfully planned and completed—one that, first, assures thepreservation of a building’s important or “character-defining” architectural materials and features and,second, makes possible an efficient contemporary use. Rehabilitation guidance in each section beginswith protection and maintenance, that work which should be maximized in every project to enhanceoverall preservation goals. Next, where some deterioration is present, repair of the building’s historicmaterials and features is recommended. Finally, when deterioration is so extensive that repair is notpossible, the most problematic area of work is considered: replacement of historic materials and featureswith new materials.

To further guide the owner and developer in planning a successful rehabilitation project, those complexdesign issues dealing with new use requirements such as alterations and additions are highlighted at theend of each section to underscore the need for particular sensitivity in these areas.

Identify, Retain, and Preserve

The guidance that is basic to the treatment of all historic buildings—identifying, retaining, and preservingthe form and detailing of those architectural materials and features that are important in defining the


historic character—is always listed first in the “Recommended” column. The parallel “NotRecommended” column lists the types of actions that are most apt to cause the diminution or even loss ofthe building’s historic character. It should be remembered, however, that such loss of character is just asoften caused by the cumulative effect of a series of actions that would seem to be minor interventions.Thus, the guidance in all of the “Not Recommended” columns must be viewed in that larger context, e.g.,for the total impact on a historic building.

Protect and Maintain

After identifying those materials and features that are important and must be retained in the process ofrehabilitation work, then protecting and maintaining them are addressed. Protection generally involvesthe least degree of intervention and is preparatory to other work. For example, protection includes themaintenance of historic material through treatments such as rust removal, caulking, limited paint removal,and re-application of protective coatings; the cyclical cleaning of roof gutter systems; or installation offencing, protective plywood, alarm systems and other temporary protective measures. Although a historicbuilding will usually require more extensive work, an overall evaluation of its physical condition shouldalways begin at this level.

Repair

Next, when the physical condition of character-defining materials and features warrants additional workrepairing is recommended. Guidance for the repair of historic materials such as masonry, wood, andarchitectural metals again begins with the least degree of intervention possible such as patching, piecing-in, splicing, consolidating, or otherwise reinforcing or upgrading them according to recognizedpreservation methods. Repairing also includes the limited replacement in kind—or with compatiblesubstitute material—of extensively deteriorated or missing parts of features when there are survivingprototypes (for example, brackets, dentils, steps, plaster, or portions of slate or tile roofing.) Althoughusing the same kind of material is always the preferred option, substitute material is acceptable if the formand design as well as the substitute material itself convey the visual appearance of the remaining parts ofthe feature and finish.

Replace

Following repair in the hierarchy, guidance is provided for replacing an entire character-defining featurewith new material because the level of deterioration or damage of materials precludes repair (for example,an exterior cornice; and interior staircase; or a complete porch or storefront). If the essential form anddetailing are still evident so that the physical evidence can be used to re-establish the feature as an integralpart of the rehabilitation project, then its replacement is appropriate. Like the guidance for repair, thepreferred option is always replacement of the entire feature in kind, that is, with the same material.Because this approach may not always be technically or economically feasible, provisions are made toconsider the use of a compatible substitute material.

It should be noted that, while the National Park Service guidelines recommend the replacement of anentire character-defining feature under certain well-defined circumstances, they never recommendremoval and replacement with new material of a feature that—although damaged or deteriorated—couldreasonably be repaired and thus preserved.

Design for Missing Historic Features

When an entire interior or exterior feature is missing (for example, an entrance, or cast iron façade; or aprincipal staircase), it no longer plays a role in physically defining the historic character of the buildingunless it can be accurately recovered in form and detailing through the process of carefully documenting


the historical appearance. Where an important architectural feature is missing, its recovery isalways recommended in the guidelines as the first or preferred, course of action. Thus, if adequatehistorical, pictorial, and physical documentation exists so that the feature may be accurately reproduced,and if it is desirable to re-establish the feature as part of the building’s historical appearance, thendesigning and constructing a new feature based on such information is appropriate. However, a secondacceptable option for the replacement feature is a new design that is compatible with the remainingcharacter-defining features of the historic building. The new design should always take into account thesize, scale, and material of the historic building itself and, most importantly, should be clearlydifferentiated so that a false historical appearance is not created.

Alterations/Additions to Historic Buildings

Some exterior and interior alterations to the historic building are generally needed to assure its continueduse, but it is most important that such alterations do not radically change, obscure, or destroy character-defining spaces, materials, features, or finishes. Alterations may include providing additional parkingspace on an existing historic building site; cutting new entrances or windows on secondary elevations;inserting an additional floor; installing an entirely new mechanical system; or creating an atrium or lightwell. Alterations may also include the selective removal of buildings or other features or the environmentor building site that are intrusive and therefore detract from the overall historic character.

The construction of an exterior addition to a historic building may seem to be essential for the new use,but it is emphasized in the guidelines that such new additions should be avoided, if possible, andconsidered only after it is determined that those needs cannot be met by altering secondary, i.e., noncharacter-defining interior spaces. If, after a thorough evaluation of interior solutions, an exterioraddition is still judged to be the only viable alternative, it should be designed and constructed to be clearlydifferentiated from the historic building and so that the character-defining features are not radicallychanged, obscured, damaged, or destroyed.

Additions to historic buildings are referenced within specific sections of the guidelines such as Site, Roof,Structural Systems, etc., but are also considered in more detail in a separate section, NEW ADDITIONSTO HISTORIC BUILDINGS.

Health and Safety Code Requirements; Energy Retrofitting

These sections of the rehabilitation guidance address work done to meet health and safety coderequirements (for example, providing barrier-free access to historic buildings); or retrofitting measures toconserve energy (for example, installing solar collectors in an unobtrusive location on the site). Althoughthis work is quite often an important aspect of rehabilitation projects, it is usually not part of the overallprocess of protecting or repairing character-defining features; rather, such work is assessed for itspotential negative impact on the building’s historic character. For this reason, particular care must betaken not to radically change, obscure, damage, or destroy character-defining materials or features in theprocess of rehabilitation work to meet code and energy requirements.

Specific information on rehabilitation and preservation technology may be obtained by writing to theNational Park Service, at the addresses listed below:

Preservation Assistance Division Preservation Services DivisionNational Park Service Southeast Regional OfficeDepartment of the Interior National Park ServiceWashington, D.C. 20240 75 Spring St. SW., Room 1140

Atlanta, GA 30303


National Historic Preservation Office of Cultural Programs Programs Mid-Atlantic Regional OfficeWestern Regional Office National Park ServiceNational Park Service 143 S. Third St.450 Golden Gate Ave. Philadelphia, PA 19106Box 36063San Francisco, CA 94102

Division of Cultural Resources Cultural Resources DivisionRocky Mountain Regional Office Alaska Regional OfficeNational Park Service National Park Service655 Parfet St. 2525 Gambell St.P.O. Box 25287 Anchorage, AK 99503Denver, CO 80225

BUILDING EXTERIOR

Masonry: Brick, stone, terra cotta, concrete, adobe, stucco and mortarMasonry features (such as brick cornices and door pediments, stone window architraves, terra cottabrackets and railings) as well as masonry surfaces (modelling, tooling, bonding patterns, joint size, andcolor) may be important in defining the historic character of the building. It should be noted that whilemasonry is among the most durable of historic building materials, it is also the most susceptible todamage by improper maintenance or repair techniques and by harsh or abrasive cleaning methods. Mostpreservation guidance on masonry thus focuses on such concerns as cleaning and the process ofrepointing.

Recommended Not Recommended

Removing or radically changing masonry featureswhich are important in defining the overall historiccharacter or the building so that, as a result, thecharacter is diminished.

Identifying, retaining, and preserving masonryfeatures that are important in defining the overallhistoric character of the building such as walls,brackets, railings, cornices, window architraves,door pediments, steps, and columns; and joint and unitsize, tooling and bonding patterns, coatings, and color.

Replacing or rebuilding a major portion of exteriormasonry walls that could be repaired so that, as aresult, the building is no longer historic and isessentially new construction.

Applying paint or other coatings such as stucco tomasonry that has been historically unpainted oruncoated to create a new appearance.

Removing paint from historically painted masonry.

Radically changing the type of paint or coating or itscolor.


Protecting and maintaining masonry by providingproper drainage so that water does not stand on flat,horizontal surfaces or accumulate in curveddecorative features.

Failing to evaluate and treat the various causes ofmortar joint deterioration such as leaking roofs orgutters, differential settlement of the building,capillary action, or extreme weather exposure.

Cleaning masonry only when necessary to haltdeterioration or remove heavy soiling.

Cleaning masonry surfaces when they are not heavilysoiled to create a new appearance, thus needlesslyintroducing chemicals or moisture into historicmaterials.

Carrying out masonry surface cleaning tests after it hasbeen determined that such cleaning is necessary. Testsshould be observed over a sufficient period of time sothat both the immediate effects and the long-rangeeffects are known to enable selection of the gentlestmethod possible.

Cleaning masonry surfaces without testing or withoutsufficient time for the testing results to be of value.

Cleaning masonry surfaces with the gentlest methodpossible, such as low-pressure water and detergents,using natural bristle brushes.

Sandblasting brick or stone surfaces using dry or wetgrit or other abrasives. These methods of cleaningpermanently erode the surface of the material andaccelerate deterioration.

Using a cleaning method that involves water or liquidchemical solutions when there is any possibility offreezing temperatures.

Cleaning with chemical products that will damagemasonry, such as using acid on limestone or marble,or leaving chemicals on masonry surfaces.

Applying high-pressure water cleaning methods thatwill damage historic masonry and the mortar joints.

Inspecting painted masonry surfaces to determinewhether repainting is necessary.

Removing paint that is firmly adhering to, and thusprotecting, masonry surfaces.

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

Using methods of removing paint which aredestructive to masonry, such as sandblasting,application of caustic solutions, or high-pressurewater blasting.

Applying compatible paint coating systems followingproper surface preparation.

Failing to follow manufacturers’ product andapplication instructions when repainting masonry.

Repainting with colors that are historically appropriateto the building and district.

Using new paint colors that are inappropriate to thehistoric building and district.


Repairing masonry walls and other masonry featuresby repointing the mortar joints where there is evidenceof deterioration such as disintegrating mortar, cracks inmortar joints, loose bricks, damp walls, or damagedplasterwork.

Removing nondeteriorated mortar from sound joints,then repointing the entire building to achieve auniform appearance.

Removing deteriorated mortar by carefully hand-rakingthe joints to avoid damaging the masonry.

Using electric saws and hammers rather than handtools to remove deteriorated mortar from joints priorto repointing.

Duplicating old mortar in strength, composition, color,and texture.

Repointing with mortar of high portland cementcontent (unless it is the content of the historicmortar). This can often create a bond that is strongerthan the historic material and can cause damageas a result of the differing coefficient of expansionand the differing porosity of the material and themortar.

Repointing with a synthetic caulking compound.

Using a “scrub” coating technique to repoint insteadof traditional repointing methods.

Duplicating old mortar joints in width and in jointprofile.

Changing the width or joint profile when repointing.

Repairing stucco by removing the damaged materialand patching with new stucco that duplicates the old instrength, composition, color, and texture.

Removing sound stucco; or repairing with newstucco that is stronger than the historic material ordoes not convey the same visual appearance.

Using mud plaster as a surface coating over unfired,unstabilized adobe because the mud plaster will bond tothe adobe.

Applying cement stucco to unfired, unstabilizedadobe. Because the cement stucco will not bondproperly, moisture can become entrapped betweenmaterials, resulting in accelerated deterioration of theadobe.

Replacing an entire masonry feature such as acornice or balustrade when repair of the masonry andlimited replacement of deteriorated or missing partsare appropriate.

Repairing masonry features by patching, piecing-in, orconsolidating the masonry using recognizedpreservation methods. Repair may also include thelimited replacement in kind—or with compatiblesubstitute material—of those extensively deterioratedor missing parts of masonry features when there aresurviving prototypes such as terra-cotta bracketsor stone balusters.

Using a substitute material for the replacement partthat does not convey the visual appearance of thesurviving parts of the masonry feature or that isphysically or chemically incompatible.

Applying new or non-historic surface treatments suchas water-repellent coatings to masonry only afterrepointing and only if masonry repairs have failed toarrest water penetration problems.

Applying waterproof, water-repellent, or non-historiccoatings such as stucco to masonry as a substitute forrepointing and masonry repairs. Coatings arefrequently unnecessary, expensive, and may changethe appearance of historic masonry as well asaccelerate its deterioration.


Replacing in kind an entire masonry feature that is toodeteriorated to repair—if the overall form and detailingare still evident—using the physical evidence to guidethe new work. Examples can include large sections ofa wall, a cornice, balustrade, column, or stairway. Ifusing the same kind of material is not technically oreconomically feasible, then a compatible substitutematerial may be considered.

Removing a masonry feature that is unrepairable andnot replacing it; or replacing it with a new featurethat does not convey the same visual appearance.

The following work is highlighted to indicate that it represents the particularly complex technical ordesign aspects of rehabilitation projects and should only be considered after the preservation concernslisted above have been addressed.


Designing and installing a new masonry feature suchas steps or a door pediment when the historic feature iscompletely missing. It may be an accurate restorationusing historical, pictorial, and physical documentationor be a new design that is compatible with the size,scale, material, and color of the historic building.

Creating a false historical appearance because thereplaced masonry feature is based on insufficienthistorical, pictorial, and physical documentation.

Introducing a new masonry feature that isincompatible in size, scale, material and color.

Woods Clapboard, weatherboard, shingles, and other wooden siding and decorative elements

Because it can be easily shaped by sawing, planing, carving, and gouging, wood is the most commonly usedmaterial for architectural features such as clapboards, cornices, brackets, entablatures, shutters, columns andbalustrades. These wooden features—both functional and decorative—may be important in defining thehistoric character of the building and thus their retention, protection, and repair are or particular importance inrehabilitation projects.


Removing or radically changing wood features whichare important in defining the overall historiccharacter of the building so that, as a result, thecharacter is diminished.

Identifying, retaining, and preserving wood featuresthat are important in defining the overall historiccharacter of the building such as siding, cornices,brackets, window architraves, and doorway pediments;and their paints, finishes, and colors.

Removing a major portion of the historic wood froma façade instead of repairing or replacing only thedeteriorated wood, then reconstructing the façadewith new material in order to achieve a uniform or“improved” appearance.

Radically changing the type of finish or its color oraccent scheme so that the historic character of theexterior is diminished.

Stripping historically painted surfaces to bare wood,then applying clear finishes or stains in order tocreate a “natural look.”


Stripping paint or varnish to bare wood rather thanrepairing or reapplying a special finish, i.e., a grainedfinish to an exterior wood feature such as a frontdoor.

Protecting and maintaining wood features byproviding proper drainage so that water is not allowedto stand on flat, horizontal surfaces or accumulate indecorative features.

Failing to identify, evaluate, and treat the causes ofwood deterioration, including faulty flashing, leakinggutters, cracks and holes in siding, deterioratedcaulking in joints and seams, plant material growingtoo close to wood surfaces, or insect or fungusinfection.

Applying chemical preservatives to wood features suchas beam ends or outriggers that are exposed to decayhazards and are traditionally unpainted.

Using chemical preservatives such as creosote whichcan change the appearance of wood features unlessthey were used historically.

Retaining coatings such as paint that help protect thewood from moisture and ultraviolet light. Paint removalshould be considered only where there is paint surfacedeterioration and as part of an overall maintenanceprogram which involves repainting or applying otherappropriate protective coatings.

Stripping paint or other coatings to reveal bare wood,thus exposing historically coated surfaces to theeffects of accelerated weathering.

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

Removing paint that is firmly adhering to, and thus,protecting wood surfaces.

Removing damaged or deteriorated paint to the nextsound layer using the gentlest method possible(handscraping and handsanding), then repainting.

Using destructive paint removal methods such aspropane or butane torches, sandblasting orwaterblasting. These methods can irreversiblydamage historic woodwork.

Using with care electric hot-air guns on decorativewood features and electric heat plates on flat woodsurfaces when paint is so deteriorated that totalremoval is necessary prior to repainting.

Using thermal devices improperly so that the historicwoodwork is scorched.

Failing to neutralize the wood thoroughly after usingchemicals so that new paint does not adhere.

Using chemical strippers primarily to supplement othermethods such as handscraping, handsanding and theabove-recommended thermal devices. Detachablewooden elements such as shutters, doors, and columnsmay—with the proper safeguards—be chemicallydip-stripped.

Allowing detachable wood features to soak too longin a caustic solution so that the wood grain is raisedand the surface roughened.

Applying compatible paint coating systems followingproper surface preparation.

Failing to follow manufacturers’ product andapplication instructions when repainting exteriorwoodwork.

Repainting with colors that are appropriate to thehistoric building and district.

Using new colors that are inappropriate to thehistoric building or district.

Evaluating the overall condition of the wood todetermine whether more than protection andmaintenance are required, that is, if repairs to woodfeatures will be necessary.

Failing to undertake adequate measures to assure thepreservation of wood features.


Replacing an entire wood feature such as a cornice orwall when repair of the wood and limitedreplacement of deteriorated or missing parts areappropriate.

Repairing wood features by patching, piecing-in,consolidating, or otherwise reinforcing the wood usingrecognized preservation methods. Repair may alsoinclude the limited replacement in kind—or withcompatible substitute material—of those extensivelydeteriorated or missing parts of features where there aresurviving prototypes such as brackets, moldings, orsections or siding.

Using substitute material for the replacement partthat does not convey the visual appearance of thesurviving parts of the wood feature or that isphysically or chemically incompatible.

Replacing in kind an entire wood feature, that is toodeteriorated to repair—if the overall form and detailingare still evident—using the physical evidence toguide the new work. Examples of wood featuresinclude a cornice, entablature or balustrade. If usingthe same kind of material is not technically oreconomically feasible, then a compatible substitutematerial may be considered.

Removing an entire wood feature that is unrepairableand not replacing it; or replacing it with a newfeature that does not convey the same visualappearance.

The following work is highlighted because it represents the particularly complex technical or designaspects of rehabilitation projects and should only be considered after the preservation concerns listedabove have been addressed.


Creating a false historic appearance because thereplaced wood feature is based on insufficienthistorical, pictorial, and physical documentation.

Designing and installing a new wood feature such as acornice or doorway when the historic feature iscompletely missing. It may be an accurate restorationusing historical, pictorial, and physical documentationor be a new design that is compatible with the size,scale, material, and color of the historic building.

Introducing a new wood feature that is incompatiblein size, scale, material, and color.

Architectural Metals: Cast iron, steel, pressed tin, copper, aluminum, and zincArchitectural metal features—such as cast-iron facades, porches, and steps; sheet metal cornices, roofs, roofcresting and storefronts; and cast or rolled metal doors, window sash, entablatures, and hardware—are oftenhighly decorative and may be important in defining the overall historic character of the building. Theirretention, protection, and repair should be a prime consideration in rehabilitation projects.


Identifying, retaining, and preserving architecturalmetal features such as columns, capitals, windowhoods, or stairways that are important in defining theoverall historic character of the building; and theirfinishes and colors.

Removing or radically changing architectural metalfeatures which are important in defining the overallhistoric character of the building so that, as aresult, the character is diminished.


Removing a major portion of the historicarchitectural metal from a façade instead of repairingor replacing only the deteriorated metal, thenreconstructing the façade with new material in orderto create a uniform, or “improved’ appearance.

Radically changing the type of finish or its historiccolor or accent scheme.

Failing to identify, evaluate, and treat the causes ofcorrosion, such as moisture from leaking roofs orgutters.

Protecting and maintaining architectural metals fromcorrosion by providing proper drainage so that waterdoes not stand on flat, horizontal surfaces oraccumulate in curved, decorative features.

Placing incompatible metals together withoutproviding a reliable separation material. Suchincompatibility can result in galvanic corrosion of theless noble metal, e.g., copper will corrode cast iron,steel, tin, and aluminum.

Exposing metals which were intended to be protectedfrom the environment.

Cleaning architectural metals, when necessary, toremove corrosion prior to repainting or applying otherappropriate protective coatings.

Applying paint or other coatings to metals such ascopper, bronze, or stainless steel that were meant tobe exposed.

Using cleaning methods which alter or damage thehistoric color, texture, and finish of the metal; orcleaning when it is inappropriate for the metal.

Identifying the particular type of metal prior to anycleaning procedure and then testing to assure that thegentlest cleaning method possible is selected ordetermining that cleaning is inappropriate for theparticular metal. Removing the patina of historic metal. The patina

may be a protective coating on some metals, such asbronze or copper, as well as a significant historicfinish.

Cleaning soft metals such as lead, tin, copper,terneplate, and zinc with appropriate chemical methodsbecause their finishes can be easily abraded byblasting methods.

Cleaning soft metals such as lead, tin, copper,terneplate, and zinc with grit blasting which willabrade the surface of the metal.

Using the gentlest cleaning methods for cast iron,wrought iron, and steel—hard metals—in order toremove paint buildup and corrosion. If handscrapingand wire brushing have proven ineffective, lowpressure dry grit blasting may be used as long as it doesnot abrade or damage the surface.

Failing to employ gentler methods prior to abrasivelycleaning cast iron, wrought iron or steel; or usinghigh pressure grit blasting.

Applying appropriate paint or other coating systemsafter cleaning in order to decrease the corrosion rate ofmetals or alloys.

Failing to re-apply protective coating systems tometals or alloys that require them after cleaning sothat accelerated corrosion occurs.

Repainting with colors that are appropriate to thehistoric building or district.

Using new colors that are inappropriate to thehistoric building or district.


Applying an appropriate protective coating such aslacquer to an architectural metal feature such as abronze door which is subject to heavy pedestrian use.

Failing to assess pedestrian use or new accesspatterns so that architectural metal features aresubject to damage by use or inappropriatemaintenance such as salting adjacent sidewalks.

Evaluating the overall condition of the architecturalmetals to determine whether more than protection andmaintenance are required, that is, if repairs to featureswill be necessary.

Failing to undertake adequate measures to assure thepreservation of architectural metal features.

Replacing an entire architectural metal feature suchas a column or a balustrade when repair of the metaland limited replacement of deteriorated or missingparts are appropriate.

Repairing architectural metal features by patching,splicing, or otherwise reinforcing the metal followingrecognized preservation methods. Repairs may alsoinclude the limited replacement in kind—or with acompatible substitute material—of those extensivelydeteriorated or missing parts of features when there aresurviving prototypes such as porch balusters, columncapitals or bases; or porch cresting.

Using a substitute material for the replacement partthat does not convey the visual appearance of thesurviving parts of the architectural metal feature or isthat physically or chemically incompatible.

Replacing in kind an entire architectural metal featurethat is too deteriorated to repair—if the overall formand detailing are still evident—using the physicalevidence to guide the new work. Examples couldinclude cast iron porch steps or steel sash windows. Ifusing the same kind of material is not technically oreconomically feasible, then a compatible substitutematerial may be considered.

Removing an architectural metal feature that isunrepairable and not replacing it; or replacing it witha new architectural metal feature that does notconvey the same visual appearance.



Creating a false historic appearance because thereplaced architectural metal feature is based oninsufficient historical, pictorial, and physicaldocumentation.

Designing and installing a new architectural metalfeature such as a sheet metal cornice or cast iron capitalwhen the historic feature is completely missing. It maybe an accurate restoration using historical, pictorial, andphysical documentation; or be a new design that iscompatible with the size, scale, material, and color ofthe historic building.

Introducing a new architectural metal feature that isincompatible in size, scale, material, and color.

RoofsThe roof—with its shape; features such as cresting, dormers, cupolas, and chimneys; and the size, color, andpatterning of the roofing material—can be extremely important in defining the building’s overall historiccharacter. In addition to the design role it plays, a weathertight roof is essential to the preservation of the entirestructure; thus, protecting and repairing the roof as a “cover” is a critical aspect of every rehabilitation project.



Radically changing, damaging, or destroying roofswhich are important in defining the overall historiccharacter of the building so that, as a result, thecharacter is diminished.

Identifying, retaining, and preserving roofs—andtheir functional and decorative features—that areimportant in defining the overall historic character ofthe building. This includes the roof’s shape, such ashipped, gambrel, and mansard; decorative features suchas cupolas, cresting, chimneys, and weathervanes; androofing material such as slate, wood, clay tile, andmetal, as well as its size, color, and patterning.

Removing a major portion of the roof or roofingmaterial that is repairable, then reconstructing it withnew material in order to create a uniform, or“improved” appearance.

Changing the configuration of a roof by adding newfeatures such as dormer windows, vents, or skylightsso that the historic character is diminished.

Stripping the roof of sound historic material such asslate, clay tile, wood, and architectural metal.

Applying paint or other coatings to roofing materialwhich has been historically uncoated.

Protecting and maintaining a roof by cleaning thegutters and downspouts and replacing deterioratedflashing. Roof sheathing should also be checked forproper venting to prevent moisture condensation andwater penetration; and to insure that materials are freefrom insect infestation.

Failing to clean and maintain gutters and downspoutsproperly so that water and debris collect and causedamage to roof fasteners, sheathing, and theunderlying structure.

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

Allowing roof fasteners, such as nails and clips tocorrode so that roofing material is subject toaccelerated deterioration.

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

Permitting a leaking roof to remain unprotected sothat accelerated deterioration of historic buildingmaterials—masonry, wood, plaster, paint andstructural members—occurs.

Replacing an entire roof feature such as a cupola ordormer when repair of the historic materials andlimited replacement of deteriorated or missing partsare appropriate.

Repairing a roof by reinforcing the historic materialswhich comprise roof features. Repairs will alsogenerally include the limited replacement in kind—orwith compatible substitute material—of thoseextensively deteriorated or missing parts of featureswhen there are surviving prototypes such as cupolalouvers, dentils, dormer roofing; or slates, tiles, orwood shingles on a main roof.

Using a substitute material for the replacement partthat does not convey the visual appearance of thesurviving parts of the roof or that is physically orchemically incompatible.


Replacing in kind an entire feature of the roof that istoo deteriorated to repair—if the overall form anddetailing are still evident—using the physical evidenceto guide the new work. Examples can include a largesection of roofing, or a dormer or chimney. If using thesame kind of material is not technically oreconomically feasible, then a compatible substitutematerial may be considered.

Removing a feature of the roof that is unrepairable,such as a chimney or dormer, and not replacing it; orreplacing it with a new feature that does not conveythe same visual appearance.



Creating a false historical appearance because thereplaced feature is based on insufficient historical,pictorial, and physical documentation.

Designing and constructing a new feature when thehistoric feature is completely missing, such as achimney or cupola. It may be an accurate restorationusing historical, pictorial, and physical documentation;or be a new design that is compatible with the size,scale, material, and color of the historic building.

Introducing a new roof feature that is incompatible insize, scale, material, and color.

Alterations/Additions for the New Use

Installing mechanical and service equipment on theroof such as air conditioning, transformers, or solarcollectors when required for the new use so that theyare inconspicuous from the public right-of-way and donot damage or obscure character-defining features.

Installing mechanical or service equipment so that itdamages or obscures character-defining features; oris conspicuous from the public right-of-way.

Designing additions to roofs such as residential, office,or storage spaces; elevator housing; decks and terraces;or dormers or skylights when required by the new useso that they are inconspicuous from the public right-of-way and do not damage or obscure character-definingfeatures.

Radically changing a character-defining roof shapeor damaging or destroying character-defining roofingmaterial as a result of incompatible design orimproper installation techniques.

WindowsA highly decorative window with an unusual shape, or glazing pattern, or color is most likely identifiedimmediately as a character-defining feature of the building. It is far more difficult, however, to assess theimportance of repeated windows on a façade, particularly if they are individually simple in design and material,such as the large, multi-paned sash of many industrial buildings. Because rehabilitation projects frequentlyinclude proposals to replace window sash or even entire windows to improve thermal efficiency or to create anew appearance, it is essential that their contribution to the overall historic character of the building be assessedtogether with their physical condition before specific repair or replacement work is undertaken.



Removing or radically changing windows which areimportant in defining the overall historic character ofthe building so that, as a result, the character isdiminished.

Identifying, retaining, and preserving windows—andtheir functional and decorative features—that areimportant in defining the overall historic character ofthe building. Such features can include frames, sash,muntins, glazing, sills, heads, hoodmolds, panelled ordecorated jambs and moldings, and interior and exteriorshutters and blinds.

Changing the number, location, size or glazingpattern of windows, through cutting new openings,blocking-in windows, and installing replacement sashwhich does not fit the historic window opening.

Changing the historic appearance of windowsthrough the use of inappropriate designs, materials,finishes, or colors which radically change the sash,depth of reveal, and muntin configuration; thereflectivity and color of the glazing; or theappearance of the frame.

Obscuring historic window trim with metal or othermaterial.

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

Protecting and maintaining the wood andarchitectural metal which comprise the window frame,sash, muntins, and surrounds through appropriatesurface treatments such as cleaning, rust removal,limited paint removal, and re-application of protectivecoating systems.

Failing to provide adequate protection of materialson a cyclical basis so that deterioration of thewindows results.

Making windows weather tight by re-caulking andreplacing or installing weather-stripping. These actionsalso improve thermal efficiency.

Retrofitting or replacing windows rather thanmaintaining the sash, frame, and glazing.

Evaluating the overall condition of materials todetermine whether more than protection andmaintenance are required, i.e. if repairs to windows andwindow features will be required.

Failing to undertake adequate measures to assure thepreservation of historic windows.

Replacing an entire window when repair of materialsand limited replacement of deteriorated or missingparts are appropriate.

Repairing window frames and sash by patching,splicing, consolidating or otherwise reinforcing. Suchrepair may also include replacement in kind of thoseparts that are either extensively deteriorated or aremissing when there are surviving prototypes such asarchitraves, hoodmolds, sash, sills, and interior orexterior shutters and blinds.

Failing to reuse serviceable window hardware suchas brass lifts and sash locks.

Using a substitute material for the replacement partthat does not convey the visual appearance of thesurviving parts of the window or that is physicallyor chemically incompatible.


Replacing in kind an entire window that is toodeteriorated to repair—if the overall form and detailingare still evident—using the physical evidence to guidethe new work. If using the same kind of material is nottechnically or economically feasible, then a compatiblesubstitute material may be considered.

Removing a character-defining window that isunrepairable and blocking it in; or replacing it with anew window that does not convey the same visualappearance.



Creating a false historical appearance because thereplaced window is based on insufficient historical,pictorial, and physical documentation.

Designing and installing new windows when thehistoric windows (frame, sash and glazing) arecompletely missing. The replacement windows may bean accurate restoration using historical, pictorial, andphysical documentation; or be a new design that iscompatible with the window openings and the historiccharacter of the building.

Introducing a new design that is incompatible withthe historic character of the building.


Designing and installing additional windows on rear orother non-character-defining elevations if required bythe new use. New window openings may also be cutinto exposed party walls. Such design should becompatible with the overall design of the building, butnot duplicate the fenestration pattern and detailing of acharacter-defining elevation.

Installing new windows, including frames, sash, andmuntin configuration that are incompatible with thebuilding’s historic appearance or obscure, damage, ordestroy character-defining features.

Providing a setback in the design of dropped ceilingswhen they are required for the new use to allow for thefull height of the window openings.

Inserting new floors or furred-down ceilings whichcut across the glazed areas of windows so that theexterior form and appearance of the windows arechanged.

Entrances And PorchesEntrances and porches are quite often the focus of historic buildings, particularly when they occur on primaryelevations. Together with their functional and decorative features such as doors, steps, balustrades, pilasters,and entablatures, they can be extremely important in defining the overall historic character of a building. Theirretention, protection, and repair should always be carefully considered when planning rehabilitation work.


Identifying, retaining, and preserving entrances—and their functional and decorative features—that areimportant in defining the overall historic character ofthe building such as doors, fanlights, sidelights,pilasters, entablatures, columns, balustrades, and stairs.

Removing or radically changing entrances andporches which are important in defining the overallhistoric character of the building so that, as a result,the character is diminished.


Stripping entrances and porches of historic materialsuch as wood, iron, cast iron, terra cotta, tile andbrick.

Removing an entrance or porch because the buildinghas been reoriented to accommodate a new use.

Cutting new entrances on a primary elevation.

Altering utilitarian or service entrances so theyappear to be formal entrances by adding panelleddoors, fanlights, and sidelights.

Protecting and maintaining the masonry, wood, andarchitectural metal that comprise entrances and porchesthrough appropriate surface treatments such ascleaning, rust removal, limited paint removal, andreapplication of protective coating systems.

Failing to provide adequate protection to materials ona cyclical basis so that deterioration of entrances andporches results.

Evaluating the overall condition of materials todetermine whether more than protection andmaintenance are required, that is, if repairs to entranceand porch features will be necessary.

Failing to undertake adequate measures to assure thepreservation of historic entrances and porches.

Replacing an entire entrance or porch when the repairof materials and limited replacement of parts areappropriate.

Repairing entrances and porches by reinforcing thehistoric materials. Repair will also generally includethe limited replacement in kind—or with compatiblesubstitute material—of those extensively deterioratedor missing parts of repeated features where there aresurviving prototypes such as balustrades cornices,entablatures, columns, sidelights, and stairs.

Using a substitute material for the replacement partsthat does not convey the visual appearance of thesurviving parts of the entrance and porch or that isphysically or chemically incompatible.

Replacing in kind an entire entrance or porch that istoo deteriorated to repair—if the form and detailing arestill evident—using the physical evidence to guide thenew work. If using the same kind of material is nottechnically or economically feasible, then a compatiblesubstitute material may be considered.

Removing an entrance or porch that is unrepairableand not replacing it; or replacing it with a newentrance or porch that does not convey the samevisual appearance.



Creating a false historical appearance because thereplaced entrance or porch is based on insufficienthistorical, pictorial, and physical documentation.

Designing and constructing a new entrance or porch ifthe historic entrance or porch is completely missing. Itmay be a restoration based on historical, pictorial, andphysical documentation; or be a new design that iscompatible with the historic character of the building. Introducing a new entrance or porch that is

incompatible in size, scale, material, and color.



Designing enclosures for historic porches whenrequired by the new use in a manner that preserves thehistoric character of the building. This can includeusing large sheets of glass and recessing the enclosurewall behind existing scrollwork, posts, and balustrades.

Enclosing porches in a manner that results in adiminution or loss of historic character such as usingsolid materials such as wood, stucco, or masonry.

Designing and installing additional entrances orporches when required for the new use in a mannerthat preserves the historic character of the building, i.e.,limiting such alteration to non-character-definingelevations.

Installing secondary service entrances and porchesthat are incompatible in size and scale with thehistoric building or obscure, damage, or destroycharacter-defining features.

StorefrontsStorefronts are quite often the focus of historic commercial buildings and can thus be extremely important indefining the overall historic character. Because storefronts also play a crucial role in a store’s advertising andmerchandising strategy to draw customers and increase business, they are often altered to meet the needs of anew business. Particular care is required in planning and accomplishing work on storefronts so that thebuilding’s historic character is preserved in the process of rehabilitation.


Removing or radically changing storefronts—andtheir features—which are important in defining theoverall historic character of the building so that, as aresult, the character is diminished.

Identifying, retaining, and preserving storefronts—and their functional and decorative features—that areimportant in defining the overall historic character ofthe building such as display windows, signs, doors,transoms, kick plates, corner posts, and entablatures.

Changing the storefront so that is appears residentialrather than commercial in character.

Removing historic material from the storefront tocreate a recessed arcade.

Introducing coach lanterns, mansard overhangings,wood shakes, nonoperable shutters, and small-panedwindows if they cannot be documented historically.

Changing the location of a storefront’s mainentrance.

Protecting and maintaining masonry, wood, andarchitectural metals which comprise storefronts throughappropriate treatments such as cleaning, rust removal,limited paint removal, and reapplication of protectivecoating systems.

Failing to provide adequate protection to materials ona cyclical basis so that deterioration of storefrontfeatures results.

Protecting storefronts against arson and vandalismbefore work begins by boarding up windows andinstalling alarm systems that are keyed into localprotection agencies.

Permitting entry into the building through unsecuredor broken windows and doors so that interiorfeatures and finishes are damaged through exposureto weather or through vandalism.

Stripping storefronts of historic material such aswood, cast iron, terra cotta, carrara glass, and brick.


Evaluating the overall condition of storefront materialsto determine whether more than protection andmaintenance are required, that is, if repairs to featureswill be necessary.

Failing to undertake adequate measures to assure thepreservation of the historic storefront.

Replacing an entire storefront when repair ofmaterials and limited replacement of its parts areappropriate.

Repairing storefronts by reinforcing the historicmaterials. Repairs will also generally include thelimited replacement in kind—or with compatiblesubstitute material—of those extensively deterioratedor missing parts of storefronts where there aresurviving prototypes such as transoms, kick plates,pilasters, or signs.

Using substitute material for the replacement partsthat does not convey the same visual appearance asthe surviving parts of the storefront or that isphysically or chemically incompatible.

Replacing in kind an entire storefront that is toodeteriorated to repair—if the overall form and detailingare still evident—using the physical evidence to guidethe new work. If using the same material is nottechnically or economically feasible, then compatiblesubstitute materials may be considered.

Removing a storefront that is unrepairable and notreplacing it; or replacing it with a new storefront thatdoes not convey the same visual appearance.



Creating a false historical appearance because thereplaced storefront is based on insufficient historical,pictorial, and physical documentation.

Introducing a new design that is incompatible in size,scale, material, and color.

Designing and constructing a new storefront when thehistoric storefront is completely missing. It may be anaccurate restoration using historical, pictorial, andphysical documentation; or be a new design that iscompatible with the size, scale, material, and color ofthe historic building. Such new design shouldgenerally be flush with the façade; and the treatment ofsecondary design elements, such as awnings or signs,kept as simple as possible. For example, new signsshould fit flush with the existing features of the façade,such as the fascia board or cornice.

Using new illuminated signs; inappropriately scaledsigns and logos; signs that project over the sidewalkunless they were a characteristic feature of thehistoric building; or other types of signs that obscure,damage, or destroy remaining character-definingfeatures of the historic building.

BUILDING INTERIORStructural SystemIf features of the structural system are exposed such as loadbearing brick walls, cast iron columns, rooftrusses, posts and beams, vigas, or stone foundation walls, they may be important in defining the building’soverall historic character. Unexposed structural features that are not character-defining or an entire structuralsystem may nonetheless be significant in the history of building technology; therefore, the structural systemshould always be examined and evaluated early in the project planning stage to determine both its physicalcondition and its importance to the building’s historic character or historical significance. See also Healthand Safety Code Requirements.



Removing, covering, or radically changing featuresof structural systems which are important in definingthe overall historic character of the building so that,as a result, the character is diminished.

Identifying, retaining, and preserving structuralsystems—and individual features of systems—that areimportant in defining the overall historic character ofthe building, such as post and beam systems, trusses,summer beams, vigas, cast iron columns, above-gradestone foundation walls, or loadbearing brick or stonewalls.

Putting a new use into the building which couldoverload the existing structural system; or installingequipment or mechanical systems which coulddamage the structure.

Demolishing a loadbearing masonry wall that couldbe augmented and retained and replacing it with anew wall (i.e., brick or stone), using the historicmasonry only as an exterior veneer.

Leaving known structural problems untreated such asdeflection of beams, cracking and bowing of walls,or racking of structural members.

Utilizing treatments or products that accelerate thedeterioration of structural material such asintroducing urea-formaldehyde foam insulation intoframe walls.

Protecting and maintaining the structural system bycleaning the roof gutters and downspouts; replacingroof flashing; keeping masonry, wood, andarchitectural metals in a sound condition; and assuringthat structural members are free from insect infestation.

Failing to provide proper building maintenance on acyclical basis so that deterioration of the structuralsystem results.

Examining and evaluating the physical condition of thestructural system and its individual features using non-destructive techniques such as X-ray photography.

Utilizing destructive probing techniques that willdamage or destroy structural material.

Repairing the structural system by augmenting orupgrading individual parts or features. For example,weakened structural members such as floor framingcan be spliced, braced, or otherwise supplemented andreinforced.

Upgrading the building structurally in a manner thatdiminishes the historic character of the exterior, suchas installing strapping channels or removing adecorative cornice; or damages interior features orspaces.

Replacing a structural member or other feature of thestructural system when it could be augmented andretained.

Installing a replacement feature that does not conveythe same visual appearance, e.g., replacing anexposed wood summer beam with a steel beam.

Replacing in kind—or with substitute material—thoseportions or features of the structural system that areeither extensively deteriorated or are missing whenthere are surviving prototypes such as cast ironcolumns, roof rafters or trusses, or sections ofloadbearing walls. Substitute material should conveythe same form, design, and overall visual appearance asthe historic feature; and, at a minimum, be equal to itsloadbearing capabilities.

Using substitute material that does not equal theloadbearing capabilities of the historic material anddesign or is otherwise physically or chemicallyincompatible.




Limiting any new excavations adjacent to historicfoundations to avoid undermining the structuralstability of the building or adjacent historic buildings.

Carrying out excavations or regrading adjacent to orwithin a historic building which could cause thehistoric foundation to settle, shift, or fail; or couldhave a similar effect on adjacent historic buildings.

Correcting structural deficiencies in preparation for thenew use in a manner that preserves the structuralsystem and individual character-defining features.

Radically changing interior spaces or damaging ordestroying features or finishes that are character-defining while trying to correct structuraldeficiencies in preparation for the new use.

Designing and installing new mechanical or electricalsystems when required for the new use which minimizethe number of cutouts or holes in structural members.

Installing new mechanical and electrical systems orequipment in a manner which results in numerouscuts, splices, or alterations to the structural members.

Inserting a new floor when such a radical changedamages a structural system or obscures or destroysinterior spaces, features, or finishes.

Adding a new floor when required for the new use ifsuch an alteration does not damage or destroy thestructural system or obscure, damage, or destroycharacter-defining spaces, features, or finishes.

Inserting new floors or furred-down ceilings whichcut across the glazed areas of windows so that theexterior form and appearance of the windows areradically changed.

Creating an atrium or a light well to provide naturallight when required for the new use in a manner thatassures the preservation of the structural system as wellas character-defining interior spaces, features, andfinishes.

Damaging the structural system or individualfeatures; or radically changing, damaging, ordestroying character-defining interior spaces,features, or finishes in order to create an atrium or alight well.

Interior: Spaces, Features, and FinishesAn interior floor plan, the arrangement of spaces, and built-in features and applied finishes may be individuallyor collectively important in defining the historic character of the building. Thus, their identification, retention,protection, and repair should be given prime consideration in every rehabilitation project and caution exercisedin pursuing any plan that would radically change character-defining spaces or obscure, damage or destroyinterior features or finishes.


Interior Spaces

Radically changing a floor plan or interior spaces—including individual rooms—which are important indefining the overall historic character of the buildingso that, as a result, the character is diminished.

Identifying, retaining, and preserving a floor plan orinterior spaces that are important in defining the overallhistoric character of the building. This includes thesize, configuration, proportion, and relationship ofrooms and corridors; the relationship of features tospaces; and the spaces themselves such as lobbies,reception halls, entrance halls, double parlors, theaters,auditoriums, and important industrial or commercialuse spaces.

Altering the floor plan by demolishing principalwalls and partitions to create a new appearance.


Altering or destroying interior spaces by insertingfloors, cutting through floors, lowering ceilings, oradding or removing walls.

Relocating an interior feature such as a staircase sothat the historic relationship between features andspaces is altered.

Interior Features and Finishes

Removing or radically changing features and finisheswhich are important in defining the overall historiccharacter of the building so that, as a result, thecharacter is diminished.

Installing new decorative material that obscures ordamages character-defining interior features orfinishes.

Identifying, retaining, and preserving interiorfeatures and finishes that are important in defining theoverall historic character of the building, includingcolumns, cornices, baseboards, fireplaces, and mantels,paneling, light fixtures, hardware, and flooring; andwallpaper, plaster, paint, and finishes such asstenciling, marbling, and graining; and other decorativematerials that accent interior features and provide color,texture, and patterning to walls, floors, and ceilings. Removing paint, plaster, or other finishes from

historically finished surfaces to create a newappearance (e.g., removing plaster to exposemasonry surfaces such as brick walls or a chimneypiece).

Applying paint, plaster, or other finishes to surfacesthat have been historically unfinished to create a newappearance.

Stripping historically painted wood surfaces to barewood, then applying clear finishes or stains to createa “natural look.”

Stripping paint to bare wood rather than repairing orreapplying grained or marbled finishes to featuressuch as doors and paneling.

Radically changing the type of finish or its color,such as painting a previously varnished wood feature.

Protecting and maintaining masonry, wood, andarchitectural metals which comprise interior featuresthrough appropriate surface treatments such ascleaning, rust removal, limited paint removal, andreapplication of protective coatings systems.

Failing to provide adequate protection to materials ona cyclical basis so that deterioration of interiorfeatures results.

Permitting entry into historic buildings throughunsecured or broken windows and doors so thatinterior features and finishes are damaged byexposure to weather or through vandalism.

Protecting interior features and finishes against arsonand vandalism before project work begins, erectingprotective fencing, boarding-up windows, and installingfire alarm systems that are keyed to local protectionagencies.

Stripping interiors of features such as woodwork,doors, windows, light fixtures, copper piping,radiators; or of decorative materials.


Protecting interior features such as a staircase, mantel,or decorative finishes and wall coverings againstdamage during project work by covering them withheavy canvas or plastic sheets.

Failing to provide proper protection of interiorfeatures and finishes during work so that they aregouged, scratched, dented, or otherwise damaged.

Installing protective coverings in areas of heavypedestrian traffic to protect historic features such aswall coverings, parquet flooring and panelling.

Failing to take new use patterns into consideration sothat interior features and finishes are damaged.

Removing damaged or deteriorated paints and finishesto the next sound layer using the gentlest methodpossible, then repainting or refinishing usingcompatible paint or other coating systems.

Using destructive methods such as propane or butanetorches or sandblasting to remove paint or othercoatings. These methods can irreversibly damage thehistoric materials that comprise interior features.

Repainting with colors that are appropriate to thehistoric building.

Using new paint colors that are inappropriate to thehistoric building.

Limiting abrasive cleaning methods to certain industrialor warehouse buildings where the interior masonry orplaster features do not have distinguishing design,detailing, tooling, or finishes; and where wood featuresare not finished, molded, beaded, or worked by hand.Abrasive cleaning should only be considered afterother, gentler methods have been proven ineffective.

Changing the texture and patina of character-definingfeatures through sandblasting or use of other abrasivemethods to remove paint, discoloration or plaster.This includes both exposed wood (includingstructural members) and masonry.

Evaluating the overall condition of materials todetermine whether more than protection andmaintenance are required, that is, if repairs to interiorfeatures and finishes will be necessary.

Failing to undertake adequate measures to assure thepreservation of interior features and finishes.

Replacing an entire interior feature such as astaircase, paneled wall, parquet floor, or cornice; orfinish such as a decorative wall covering or ceilingwhen repair of materials and limited replacement ofsuch parts are appropriate.

Repairing interior features and finishes by reinforcingthe historic materials. Repair will also generallyinclude the limited replacement in kind—or withcompatible substitute material—of those extensivelydeteriorated or missing parts of repeated features whenthere are surviving prototypes such as stairs,balustrades, wood paneling, columns; or decorativewall coverings or ornamental tin or plaster ceilings.

Using a substitute material for the replacement partthat does not convey the visual appearance of thesurviving parts or portions of the interior feature orfinish or that is physically or chemicallyincompatible.

Replacing in kind an entire interior feature or finishthat is too deteriorated to repair—if the overall formand detailing are still evident—using the physicalevidence to guide the new work. Examples couldinclude wainscoting, a tin ceiling, or interior stairs. Ifusing the same kind of material is not technically oreconomically feasible, then a compatible substitutematerial may be considered.

Removing a character-defining feature or finish thatis unrepairable and not replacing it; or replacing itwith a new feature or finish that does not convey thesame visual appearance.




Creating a false historical appearance because thereplaced feature is based on insufficient physical,historical, and pictorial documentation or oninformation derived from another building.

Designing and installing a new interior feature or finishif the historic feature or finish is completely missing.This could include missing partitions, stairs, elevators,lighting fixtures, and wall coverings; or even entirerooms if all historic spaces, features, and finishes aremissing or have been destroyed by inappropriate“renovations.” The design may be a restoration basedon historical, pictorial, and physical documentation; orbe a new design that is compatible with the historiccharacter of the building, district, or neighborhood.

Introducing a new interior feature or finish that isincompatible with the scale, design, materials, color,and texture of the surviving interior features andfinishes.


Accommodating service functions such as bathrooms,mechanical equipment, and office machines required bythe building’s new use in secondary spaces such as firstfloor service areas or on upper floors.

Dividing rooms, lowering ceilings, and damaging orobscuring character-defining features such asfireplaces, niches, stairways or alcoves, so that a newuse can be accommodated in the building.

Reusing decorative material or features that have had tobe removed during the rehabilitation work includingwall and baseboard trim, door molding, paneled doors,and simple wainscoting; and relocating such material orfeatures in areas appropriate to their historic placement.

Discarding historic material when it can be reusedwithin the rehabilitation project or relocating it inhistorically inappropriate areas.

Installing permanent partitions in secondary spaces;removable partitions that do not destroy the sense ofspace should be installed when the new use requires thesubdivision of character-defining interior spaces.

Installing permanent partitions that damage orobscure character-defining spaces, features, orfinishes.

Enclosing an interior stairway where required by codeso that its character is retained. In many cases, glazedfire-rated walls may be used.

Enclosing an interior stairway with fire-ratedconstruction so that the stairwell space or anycharacter-defining features are destroyed.

Placing new code-required stairways or elevators insecondary and service areas of the historic building.

Radically changing, damaging, or destroyingcharacter-defining spaces, features, or finishes whenadding new code-required stairways and elevators.

Creating an atrium or a light well to provide naturallight when required for the new use in a manner thatpreserves character-defining interior spaces,features, and finishes as well as the structural system.

Destroying character-defining interior spaces,features, or finishes; or damaging the structuralsystem in order to create an atrium or light well.

Adding a new floor if required for the new use in amanner that preserves character-defining structuralfeatures, and interior spaces, features, and finishes.

Inserting a new floor within a building that alters ordestroys the fenestration; radically changes acharacter-defining interior space; or obscures,damages, or destroys decorative detailing.


Mechanical Systems: Heating, Air Conditioning, Electrical, and PlumbingThe visible features of historic heating, lighting, air conditioning and plumbing systems may sometimes helpdefine the overall historic character of the building and should thus be retained and repaired, whenever possible.The systems themselves (the compressors, boilers, generators and their ductwork, wiring and pipes) willgenerally either need to be upgraded, augmented, or entirely replaced in order to accommodate the new use andto meet code requirements. Less frequently, individual portions of a system or an entire system are significantin the history of building technology; therefore, the identification of character-defining features or historicallysignificant systems should take place together with an evaluation of their physical condition early in projectplanning.


Identifying, retaining, and preserving visible featuresof early mechanical systems that are important indefining the overall historic character of the building,such as radiators, vents, fans, grilles, plumbing fixtures,switchplates, and lights.

Removing or radically changing features ofmechanical systems that are important in defining theoverall historic character of the building so that, as aresult, the character is diminished.

Protecting and maintaining mechanical, plumbing,and electrical systems and their features throughcyclical cleaning and other appropriate measures.

Failing to provide adequate protection of materialson a cyclical basis so that deterioration of mechanicalsystems and their visible features results.

Preventing accelerated deterioration of mechanicalsystems by providing adequate ventilation of attics,crawlspaces, and cellars so that moisture problems areavoided.

Enclosing mechanical systems in areas that are notadequately ventilated so that deterioration of thesystems results.

Repairing mechanical systems by augmenting orupgrading system parts, such as installing new pipesand ducts; rewiring; or adding new compressors orboilers.

Replacing a mechanical system or its functional partswhen it could be upgraded and retained.

Replacing in kind—or with compatible substitutematerial—those visible features of mechanical systemsthat are either extensively deteriorated or are missingwhen there are surviving prototypes such as ceilingfans, switchplates, radiators, grilles, or plumbingfixtures.

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



Installing a completely new mechanical system isrequired for the new use so that it causes the leastalteration possible to the building’s floor plan, theexterior elevations, and the least damage to historicbuilding material.

Installing a new mechanical system so that character-defining structural or interior features are radicallychanged, damaged, or destroyed.


Installing the vertical runs of ducts, pipes, and cables inclosets, service rooms, and wall cavities.

Installing vertical runs of ducts, pipes, and cables inplaces where they will obscure character-definingfeatures.

Concealing mechanical equipment in walls orceilings in a manner that requires the removal ofhistoric building material.

Installing “dropped” acoustical ceilings to hidemechanical equipment when this destroys theproportions of character-defining interior spaces.

Installing air conditioning units if required by the newuse in such a manner that the historic materials andfeatures are not damaged or obscured.

Cutting through features such as masonry walls inorder to install air conditioning units.

Installing heating/air conditioning units in the windowframes in such a manner that the sash and frames areprotected. Window installations should be consideredonly when all other viable heating/cooling systemswould result in significant damage to historic materials.

Radically changing the appearance of the historicbuilding or damaging or destroying windows byinstalling heating/air conditioning units in historicwindow frames.

BUILDING SITEThe relationship between a historic building or buildings and landscape features within a property’sboundaries—or the building site—helps to define the historic character and should be considered an integralpart of overall planning and rehabilitation project work.


Identifying, retaining, and preserving buildings andtheir features as well as features of the site that areimportant in defining its overall historic character.Site features can include driveways, walkways,lighting, fencing, signs, benches, fountains, wells,terraces, canal systems, plants and trees, berms, anddrainage or irrigation ditches; and archeologicalfeatures that are important in defining the history ofthe site.

Removing or radically changing buildings and theirfeatures or site features which are important indefining the overall historic character of the buildingsite so that, as a result, the character is diminished.

Retaining the historic relationship between buildings,landscape features, and open space.

Removing or relocating historic buildings orlandscape features, thus destroying the historicrelationship between buildings, landscape features,and open space.

Removing or relocating historic buildings on a siteor in a complex of related historic structures—suchas a mill complex or farm—thus diminishing thehistoric character of the site or complex.

Moving buildings onto the site, thus creating afalse historic appearance.


Lowering the grade level adjacent to a building topermit development of a formerly below-grade areasuch as a basement in a manner that woulddrastically change the historic relationship of thebuilding to its site.

Protecting and maintaining buildings and the site byproviding proper drainage to assure that water does noterode foundation walls; drain toward the building; norerode the historic landscape.

Failing to maintain site drainage so that buildings andsite features are damaged or destroyed; or,alternatively, changing the site grading so that waterno longer drains properly.

Minimizing disturbance of terrain around buildings orelsewhere on the site, thus reducing the possibility ofdestroying unknown archeological materials.

Introducing heavy machinery or equipment into areaswhere their presence may disturb archeologicalmaterials.

Surveying areas where major terrain alteration is likelyto impact important archeological sites.

Failing to survey the building site prior to thebeginning of rehabilitation project work so that, as aresult, important archeological material is destroyed.

Protecting, e.g. preserving in place knownarcheological material whenever possible.

Leaving known archeological material unprotectedand subject to vandalism, looting, and destruction bynatural elements such as erosion.

Planning and carrying out any necessary investigationusing professional archeologists and modernarcheological methods when preservation in place isnot feasible.

Permitting unqualified project personnel to performdata recovery so that improper methodology resultsin the loss of important archeological material.

Permitting buildings and site features to remainunprotected so that plant materials, fencing,walkways, archeological features, etc. are damagedor destroyed.

Protecting the building and other features of the siteagainst arson and vandalism before rehabilitation workbegins, i.e., erecting protective fencing and installingalarm systems that are keyed into local protectionagencies.

Stripping features from buildings and the site such aswood siding, iron fencing, masonry balustrades; orremoving or destroying landscape features, includingplant material.

Providing continued protection of masonry, wood, andarchitectural metals which comprise building and sitefeatures through appropriate surface treatments such ascleaning, rust removal, limited paint removal, andreapplication of protective coating systems; andcontinued protection and maintenance of landscapefeatures, including plant material.

Failing to provide adequate protection of materialson a cyclical basis so that deterioration of buildingand site features results.

Evaluating the overall condition of materials todetermine whether more than protection andmaintenance are required, that is, if repairs to buildingand site features will be necessary.

Failing to undertake adequate measures to assure thepreservation of building and site features.


Replacing an entire feature of the building or sitesuch as a fence, walkway, or driveway when repairof materials and limited replacement of deterioratedor missing parts are appropriate.

Repairing features of buildings and the site byreinforcing the historic materials. Repair will alsogenerally include replacement in kind—with acompatible substitute material—of those extensivelydeteriorated or missing parts of features where there aresurviving prototypes such as fencing and paving. Using a substitute material for the replacement part

that does not convey the visual appearance of thesurviving parts of the building or site feature or thatis physically or chemically incompatible.

Replacing in kind an entire feature of the building orsite that is too deteriorated to repair—if the overallform and detailing are still evident—using the physicalevidence to guide the new work. This could include anentrance or porch, walkway, or fountain. If using thesame kind of material is not technically oreconomically feasible, then a compatible substitutematerial may be considered.

Removing a feature of the building or site that isunrepairable and not replacing it; or replacing it witha new feature that does not convey the same visualappearance.



Creating a false historical appearance because thereplaced feature is based on insufficient historical,pictorial, and physical documentation.

Introducing a new building or site feature that is outof scale or otherwise inappropriate.

Designing and constructing a new feature of a buildingor site when the historic feature is completely missing,such as an outbuilding, terrace, or driveway. It may bebased on historical, pictorial, and physicaldocumentation; or be a new design that is compatiblewith the historic character of the building and site.

Introducing a new landscape feature or plant materialthat is visually incompatible with the site or thatdestroys site patterns or vistas.


Designing new onsite parking, loading docks, or rampswhen required by the new use so that they are asunobtrusive as possible and assure the preservation ofcharacter-defining features of the site.

Placing parking facilities directly adjacent to historicbuildings where automobiles may cause damage tothe buildings or landscape features or be intrusive tothe building site.

Designing new exterior additions to historic buildingsor adjacent new construction which is compatible withthe historic character of the site and which preserve thehistoric relationship between a building or buildings,landscape features, and open space.

Introducing new construction onto the building sitewhich is visually incompatible in terms of size, scale,design, materials, color and texture or which destroyshistoric relationships on the site.

Removing nonsignificant buildings, additions, or sitefeatures which detract from the historic character of thesite.

Removing a historic building in a complex, abuilding feature, or a site feature which is importantin defining the historic character of the site.


DISTRICT/NEIGHBORHOODThe relationship between historic buildings, and streetscape and landscape features within a historic districtor neighborhood helps to define the historic character and therefore should always be a part of therehabilitation plans.


Identifying, retaining, and preserving buildings, andstreetscape, and landscape features which are importantin defining the overall historic character of the districtor neighborhood. Such features can include streets,alleys, paving, walkways, streetlights, signs, benches,parks and gardens, and trees.

Removing or radically changing those features of thedistrict or neighborhood which are important indefining the overall historic character so that, as aresult, the character is diminished.

Destroying streetscape and landscape features bywidening existing streets, changing paving material,or introducing inappropriately located new streets orparking lots.

Retaining the historic relationship between buildings,and streetscape and landscape features such as a townsquare comprised of row houses and stores surroundinga communal park or open space.

Removing or relocating historic buildings, or featuresof the streetscape and landscape, thus destroying thehistoric relationship between buildings, features andopen space.

Protecting and maintaining the historic masonry,wood, and architectural metals which comprisebuilding and streetscape features, through appropriatesurface treatments such as cleaning, rust removal,limited paint removal, and reapplication of protectivecoating systems; and protecting and maintaininglandscape features, including plant material.

Failing to provide adequate protection of materialson a cyclical basis so that deterioration of building,streetscape, and landscape features results.

Permitting buildings to remain unprotected so thatwindows are broken; and interior features aredamaged.

Protecting buildings, paving, iron fencing, etc. againstarson and vandalism before rehabilitation work beginsby erecting protective fencing and installing alarmsystems that are keyed into local protection agencies.

Stripping features from buildings or the streetscapesuch as wood siding, iron fencing, or terra cottabalusters; or removing or destroying landscapefeatures, including plant material.

Evaluating the overall condition of building, streetscapeand landscape materials to determine whether morethan protection and maintenance are required, that is, ifrepairs to features will be necessary.

Failing to undertake adequate measures to assure thepreservation of building, streetscape, and landscapefeatures.

Repairing features of the building, streetscape, orlandscape by reinforcing the historic materials.Repair will also generally include the replacement inkind—or with a compatible substitute material—ofthose extensively deteriorated or missing parts offeatures when there are surviving prototypes such asporch balustrades, paving materials, or streetlightstandards.

Replacing an entire feature of the building,streetscape, or landscape such as a porch, walkway,or streetlight, when repair of materials and limitedreplacement of deteriorated or missing parts areappropriate.


Using a substitute material for the replacement partthat does not convey the visual appearance of thesurviving parts of the building, streetscape, orlandscape feature or that is physically or chemicallyincompatible.

Replacing in kind an entire feature of the building,streetscape, or landscape that is too deteriorated torepair—when the overall form and detailing are stillevident—using the physical evidence to guide the newwork. This could include a storefront, a walkway, or agarden. If using the same kind of material is nottechnically or economically feasible, then a compatiblesubstitute material may be considered.

Removing a feature of the building, streetscape, orlandscape that is unrepairable and not replacing it; orreplacing it with a new feature that does not conveythe same visual appearance.



Creating a false historical appearance because thereplaced feature is based on insufficient historical,pictorial and physical documentation.

Designing and constructing a new feature of thebuilding, streetscape, or landscape when the historicfeature is completely missing, such as row house steps,a porch, streetlight, or terrace. It may be a restorationbased on historical, pictorial, and physicaldocumentation; or be a new design that is compatiblewith the historic character of the district orneighborhood.

Introducing a new building, streetscape or landscapefeature that is out of scale or otherwise inappropriateto the setting’s historic character, e.g., replacingpicket fencing with chain link fencing.


Designing required new parking so that it is asunobtrusive as possible, i.e., on side streets or at therear of buildings. “Shared” parking should also beplanned so that several businesses can utilize oneparking area as opposed to introducing random,multiple lots.

Placing parking facilities directly adjacent to historicbuildings which cause the removal of historicplantings, relocation of paths and walkways, orblocking of alleys.

Designing and constructing new additions to historicbuildings when required by the new use. New workshould be compatible with the historic character of thedistrict or neighborhood in terms of size, scale, design,material, color, and texture.

Introducing new construction into historic districtsthat is visually incompatible or that destroys historicrelationships within the district or neighborhood.

Removing nonsignificant buildings, additions, orstreetscape and landscape features which detract fromthe historic character of the district or theneighborhood.

Removing a historic building, building feature, orlandscape or streetscape feature that is important indefining the overall historic character of the districtor the neighborhood.


Although the work in these sections is quite often an important aspect of rehabilitation projects, it is usuallynot part of the overall process of preserving character-defining features (maintenance, repair, replacement);rather, such work is assessed for its potential negative impact on the building’s historic character. For thisreason, particular care must be taken not to obscure, radically change, damage, or destroy character-defining features in the process of rehabilitation work to meet new use requirements.

HEALTH AND SAFETY CODE REQUIREMENTSAs a part of the new use, it is often necessary to make modifications to a historic building so that it can complywith current health, safety and code requirements. Such work needs to be carefully planned and undertaken sothat it does not result in a loss of character-defining spaces, features, and finishes.


Identifying the historic building’s character-definingspaces, features, and finishes so that code-requiredwork will not result in their damage or loss.

Undertaking code-required alterations to a buildingor site before identifying those spaces, features, orfinishes which are character-defining and musttherefore be preserved.

Complying with health and safety codes, includingseismic codes and barrier-free access requirements, insuch a manner that character-defining spaces, features,and finishes are preserved.

Altering, damaging, or destroying character-definingspaces, features, and finishes while makingmodifications to a building or site to comply withsafety codes.

Working with local code officials to investigatealternative life safety measures or variances availableunder some codes so that alterations and additions tohistoric buildings can be avoided.

Making changes to historic buildings without firstseeking alternatives to code requirements.

Providing barrier-free access through removable orportable, rather than permanent, ramps.

Installing permanent ramps that damage or diminishcharacter-defining features.

Providing seismic reinforcement to a historic buildingin a manner that avoids damaging the structural systemand character-defining features.

Reinforcing a historic building using measures thatdamage or destroy character-defining structural andother features.

Upgrading historic stairways and elevators to meethealth and safety codes in a manner that assures theirpreservation, i.e., so that they are not damaged orobscured.

Damaging or obscuring historic stairways andelevators or altering adjacent spaces in the processof doing work to meet code requirements.

Installing sensitively designed fire suppressionsystems, such as a sprinkler system for wood framemill buildings, instead of applying fire-resistantsheathing to character-defining features.

Covering character-defining wood features with fire-resistant sheathing which results in altering theirvisual appearance.

Applying fire-retardant coatings, such as intumescentpaints, which expand during fire to add thermalprotection to steel.

Using fire-retardant coatings if they damage orobscure character-defining features.

Adding a new stairway or elevator to meet health andsafety codes in a manner that preserves adjacentcharacter-defining features and spaces.

Radically changing, damaging, or destroyingcharacter-defining spaces, features, or finishes whenadding a new code-required stairway or elevator.


Placing a code-required stairway or elevator thatcannot be accommodated within the historic buildingin a new exterior addition. Such an addition should belocated at the rear of the building or on aninconspicuous side; and its size and scale limited inrelationship to the historic building.

Constructing a new addition to accommodate code-required stairs and elevators on character-definingelevations highly visible from the street; or where itobscures, damages or destroys character-definingfeatures.

ENERGY RETROFITTINGSome character-defining features of a historic building or site such as cupolas, shutters, transoms, skylights,sunrooms, porches, and plantings also play a secondary energy-conserving role. Therefore, prior toretrofitting historic buildings to make them more energy efficient, the first step should always be to identifyand evaluate the existing historic features to assess their inherent energy conserving potential. If it isdetermined that retrofitting measures are necessary, then such work needs to be carried out with particularcare to insure that the building’s historic character is preserved in the process of rehabilitation.


District/Neighborhood

Maintaining those existing landscape features whichmoderate the effects of the climate on the setting suchas deciduous trees, evergreen wind-blocks, and lakesor ponds.

Stripping the setting of landscape features andlandforms so that the effects of the wind, rain, andthe sun result in accelerated deterioration of historicmaterials.

Building Site

Retaining plant materials, trees, and landscapefeatures, especially those which perform passive solarenergy functions such as sun shading and wind breaks.

Removing plant materials, trees, and landscapefeatures, so that they no longer perform passive solarenergy functions.

Installing freestanding solar collection in a manner thatpreserves the historic property’s character-definingfeatures.

Installing freestanding solar collectors that obscure,damage, or destroy historic landscape orarcheological features.

Designing attached solar collectors, including solargreenhouses, so that the character-defining features ofthe property are preserved.

Locating solar collectors where they radicallychange the property’s appearance; or damage ordestroy character-defining features.

Masonry/Wood/Architectural Metals

Installing thermal insulation in attics and in unheatedcellars and crawlspaces to increase the efficiency ofthe existing mechanical systems.

Applying urea formaldehyde foam or any otherthermal insulation with a water content into wallcavities in an attempt to reduce energy consumption.

Installing insulating material on the inside of masonrywalls to increase energy efficiency where there is nocharacter-defining interior molding around the windowor other interior architectural detailing.

Resurfacing historic building materials with moreenergy efficient but incompatible materials, such ascovering historic masonry with exterior insulation.


Installing passive solar devices such as a glazed“trombe” wall on a rear or inconspicuous side of thehistoric building.

Installing passive solar devices such as an attachedglazed “trombe” wall on primary or other highlyvisible elevations; or where historic material must beremoved or obscured.

Roofs

Placing solar collectors on non-character-definingroofs or roofs of nonhistoric adjacent buildings.

Placing solar collectors on roofs when suchcollectors change the historic roofline or obscure therelationship of the roof to character-defining rooffeatures such as dormers, skylights, and chimneys.

Windows

Utilizing the inherent energy conserving features of abuilding by maintaining windows and louvered blindsin good operable condition for natural ventilation.

Removing historic shading devices rather thankeeping them in an operable condition.

Improving thermal efficiency with weather-stripping,storm windows, caulking, interior shades, and, ifhistorically appropriate, blinds and awnings.

Replacing historic multi-paned sash with newthermal sash utilizing false muntins.

Installing interior storm windows with airtight gaskets,ventilating holes, and/or removable clips to insureproper maintenance and to avoid condensation damageto historic windows.

Installing interior storm windows that allowmoisture to accumulate and damage the window.

Installing exterior storm windows that do not damageor obscure the windows and frames.

Installing new exterior storm windows that areappropriate in size or color, which are inoperable.

Replacing windows or transoms with fixed thermalglazing or permitting windows and transoms toremain inoperable rather than utilizing them for theirenergy conserving potential.

Considering the use of lightly tinted glazing on non-character-defining elevations if other energyretrofitting alternatives are not possible.

Using tinted or reflective glazing on character-defining or other conspicuous elevations.

Entrances and Porches

Utilizing the inherent energy conserving features of abuilding by maintaining porches, and double vestibuleentrances, in good condition so that they can retainheat or block the sun and provide natural ventilation.

Enclosing porches located on character-definingelevations to create passive solar collectors orairlock vestibules. Such enclosures can destroy thehistoric appearance of the building.

Interior Features

Retaining historic interior shutters and transoms fortheir inherent energy conserving features.

Removing historic interior features which play asecondary energy conserving role.

New Additions to Historic Buildings


Placing new additions that have an energy conservingfunction such as a solar greenhouse on non-character-defining elevations.

Installing new additions such as multi-story solargreenhouse additions that obscure, damage, destroycharacter-defining features.

Mechanical Systems

Installing thermal insulation in attics and in heatedcellars and crawlspaces to conserve energy.

Applying urea formaldehyde foam or any otherthermal insulation with a water content or that maycollect moisture into wall cavities.

NEW ADDITIONS TO HISTORIC BUILDINGSAn attached exterior addition to a historic building expands its “outer limits” to create a new profile. Becausesuch expansion has the capability to radically change the historic appearance, an exterior addition should beconsidered only after it has been determined that the new use cannot be successfully met by altering non-character-defining interior spaces. If the new use cannot be met in this way, then an attached exterior additionis usually an acceptable alternative. New additions should be designed and constructed so that the character-defining features of the historic building are not radically changed, obscured, damaged, or destroyed in theprocess of rehabilitation. New design should always be clearly differentiated so that the addition does notappear to be part of the historic resource.


Placing functions and services required for the newuse in non-character-defining interior spaces ratherthan installing a new addition.

Expanding the size of the historic building byconstructing a new addition when the new use couldbe met by altering non-character-defining interiorspaces.

Constructing a new addition so that there is the leastpossible loss of historic materials and so thatcharacter-defining features are not obscured, damaged,or destroyed.

Attaching a new addition so that the character-defining features of the historic building areobscured, damaged, or destroyed.

Locating the attached exterior addition at the rear or onan inconspicuous side of a historic building; andlimiting its size and scale in relationship to the historicbuilding.

Designing a new addition so that its size and scale inrelation to the historic building are out of proportion,thus diminishing the historic character.

Designing new additions in a manner that makes clearwhat is historic and what is new.

Duplicating the exact form, material, style, anddetailing of the historic building in the new additionso that the new work appears to be part of thehistoric building.

Imitating a historic style or period of architecture innew additions, especially for contemporary usessuch as drive-in banks or garages.

Considering the attached exterior addition both interms of the new use and the appearance of otherbuildings in the historic district or neighborhood.Design for the new work may be contemporary or mayreference design motifs from the historic building. Ineither case, it should always be clearly differentiatedfrom the historic building and be compatible in termsof mass, materials, relationship of solids to voids, andcolor.

Designing and constructing new additions that resultin the diminution or loss of the historic character ofthe resource, including its design, materials,workmanship, location, or setting.


Using the same wall plane, roofline, cornice height,materials, siding lap or window type to makeadditions appear to be a part of the historic building.

Placing new additions such as balconies andgreenhouses on non-character-defining elevations andlimiting the size and scale in relationship to thehistoric building.

Designing new additions such as multi-storygreenhouse additions that obscure, damage, ordestroy character-defining features of the historicbuilding.

Designing additional stories, when required for thenew use, that are set back from the wall plane and areas inconspicuous as possible when viewed from thestreet.

Constructing additional stories so that the historicappearance of the building is radically changed.

the secretary of the interior’s standards for rehabilitation … · the secretary of the...

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