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The Secretary of the Interior’s Standards and Guidelines

The Secretary of the Interior’s Standards for Rehabilitation, also known as The Standards, are part of the United States Department of the Interior – National Park Service – Secretary of the Interior’s Standards for the Treatment of Historic Properties.

The Standards are a nationally recognized tool for the preservation, maintenance and rehabilitation of our nation’s heritage. These Standards have become the accepted benchmark at all levels of government – national, state, and local – for evaluating the acceptability of proposed changes to historic properties. The City of Los Angeles utilizes the Standards in reviewing proposed alterations to City Historic-Cultural Monuments and in its Historic Preservation Overlay Zones (HPOZs).

The Standards are not meant to prevent change – instead, they represent a sophisticated and nuanced framework for managing change. The Standards do not require that every feature of a historic property be preserved, but do seek to preserve the most significant, character-defining features of a historic site. The Standards also give important guidance on how to design and construct new additions in a manner that does not detract from a property’s historic character.

The National Park Service has also published detailed Guidelines that further explain and illustrate the Standards and their practical application. In addition, many applicants retain historic preservation consultants on more complex projects to assist them in interpreting and applying the Standards.

The full Secretary of the Interior’s Standards and Guidelines are found on the National Park Service website at this link.

The Secretary of the Interior’s Standards for Rehabilitation are:

1. 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.

2. 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.

3. 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.

4. Most properties change over time; those changes that have acquired historic significance in their own right shall be retained and preserved.

5. Distinctive features, finishes, and construction techniques or examples of craftsmanship that characterize a property shall be preserved.

6. 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.

7. 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.

8. Significant archeological resources affected by a project shall be protected and preserved. If such resources must be disturbed, mitigation measures shall be undertaken.

9. 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.

10. 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.