Tool: The Secretary of the Interior’s Standards and Guidelines for Historic Rehabilitation
Under the statute that governs the federal Historic Preservation Tax Incentives program (36 CFR 67), "Rehabilitation" is defined as "the process of returning a property to a state of utility, through repair or alteration, which makes possible an efficient contemporary use while preserving those portions and features of the property which are significant to its historic, architectural, and cultural values."
The Standards:
The standards explain the nature and quality of the work expected of a historic rehabilitation.
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A property shall be used for its historic purpose or be placed in a new use that requires minimal change to the defining characteristics of the building and its site and environment.
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The historic character of a property shall be retained and preserved. The removal of historic materials or alteration of features and spaces that characterize a property shall be avoided.
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Each property shall be recognized as a physical record of its time, place, and use. Changes that create a false sense of historical development, such as adding conjectural features or architectural elements from other buildings, shall not be undertaken.
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Most properties change over time; those changes that have acquired historic significance in their own right shall be retained and preserved.
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Distinctive features, finishes, and construction techniques or examples of craftsmanship that characterize a property shall be preserved.
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Deteriorated historic features shall be repaired rather than replaced. Where the severity of deterioration requires replacement of a distinctive feature, the new feature shall match the old in design, color, texture, and other visual qualities and, where possible, materials. Replacement of missing features shall be substantiated by documentary, physical, or pictorial evidence.
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Chemical or physical treatments, such as sandblasting, that cause damage to historic materials shall not be used. The surface cleaning of structures, if appropriate, shall be undertaken using the gentlest means possible.
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Significant archeological resources affected by a project shall be protected and preserved. If such resources must be disturbed, mitigation measures shall be undertaken.
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New additions, exterior alterations, or related new construction shall not destroy historic materials that characterize the property. The new work shall be differentiated from the old and shall be compatible with the massing, size, scale, and architectural features to protect the historic integrity of the property and its environment.
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New additions and adjacent or related new construction shall be undertaken in such a manner that if removed in the future, the essential form and integrity of the historic property and its environment would be unimpaired.
The Guidelines:
The guidelines set out the order in which rehabilitation activities must be considered and carried out. That means that the first of these must be tried and completed to the extent possible before moving on to the second, which in turn must be completed before moving on to the third, etc. In practice, the architect or contractor in charge will determine beforehand what can be retained, what needs to be protected, what should be repaired, etc.
The order of consideration in rehabilitating historic buildings and building features is:
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Identify, retain, preserve (any part that’s in good shape).
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Protect and maintain (anything that’s threatened or needs cleaning or the like).
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Repair (applied to anything that isn’t so completely deteriorated that it can’t be repaired).
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Replace (with in-kind materials, design, colors, tools, workmanship, etc., where something has deteriorated past the point of repair).
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Design for missing features (should conform to what was there, if you know what it was, or can be a new, but appropriate, design when you don’t have direct evidence of what the missing features looked like or were made of).
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Alterations or additions (must be consistent with the historic materials and/or character of the original).
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Energy efficiency/Accessibility/Health and Safety. (Work on these areas must respect the historic materials, design, spaces, etc. of the original. Essentially, this means that installation of any equipment for these purposes can’t involve destruction of any original material or features, or alter the character of the structure.)