The United States Department of the Interior has developed a set of national standards for the rehabilitation of historic properties. These ten national standards describe appropriate preservation treatments in a ranked order: retain, repair, replace. The Statesville Design Guidelines are modeled after the Secretary’s Standards, the current version (1992) of which is listed below:
A property shall be used as it was historically or be given a new use that requires minimum change to its distinctive materials, features, spaces, and spatial relationships.
The historic character of a property shall be retained and preserved. The removal of distinctive materials or alteration of features, spaces, and spatial relationships that characterize a property shall be avoided.
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 elements from other historic properties, shall not be undertaken.
Changes to a property that have acquired historic significance in their own right shall be retained and preserved.
Distinctive materials, features, finishes, and construction techniques or examples of craftsmanship that characterize a property shall be preserved.
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, where possible, materials. Replacement of missing features shall be substantiated by documentary and physical evidence.
Chemical or physical treatments, if appropriate, shall be undertaken using the gentlest means possible. Treatments that cause damage to historic materials shall not be used.
Archaeological resources shall be protected and preserved in place. If such resources must be disturbed, mitigation measures shall be undertaken.
New additions, exterior alterations, or related new construction shall not destroy historic materials, features, and spatial relationships that characterize the property. The new work shall be differentiated from the old and shall be compatible with the historic materials, features, size, scale and proportion, and massing to protect the integrity of the property and its environment.
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.