The Secretary of Interior Standards for the Treatment of Historic Properties & Guidelines for Preserving, Rehabilitating, Restoring and Reconstructing Historic Buildings is the most recent incarnation of standards set forth by the Secretary of the Interior, whose power to administrate started with the passing of the National Historic Preservation Act in 1966.
There are four approaches covered by the Secretary of Interior Standards, conveyed in full via the National Park Services’ Technical Preservation Services website. These approaches are: Preservation, Rehabilitation, Restoration, and Reconstruction.
Preservation is defined as the act or process of applying measures necessary to sustain the existing form, integrity, and materials of an historic property. Work, including preliminary measures to protect and stabilize the property, generally focuses upon the ongoing maintenance and repair of historic materials and features rather than extensive replacement and new construction. New exterior additions are not within the scope of this treatment; however, the limited and sensitive upgrading of mechanical, electrical, and plumbing systems and other code-required work to make properties functional is appropriate within a preservation project.National Park Service — Technical Preservation Services
Rehabilitation is defined as the act or process of making possible a compatible use for a property through repair, alterations, and additions while preserving those portions or features which convey its historical, cultural, or architectural values.National Park Service — Technical Preservation Services
The Secretary of the Interior’s Standards for Rehabilitation, codified as 36 CFR 67, are regulatory for the Historic Preservation Tax Incentives program. The Guidelines for Rehabilitating Historic Buildings and the Guidelines on Sustainability for Rehabilitating Historic Buildings, which assist in applying the Standards, are advisory.NPS — Technical Preservation Services — Rehabilitation for Historic Tax Credit Projects
Restoration is defined as the act or process of accurately depicting the form, features, and character of a property as it appeared at a particular period of time by means of the removal of features from other periods in its history and reconstruction of missing features from the restoration period. The limited and sensitive upgrading of mechanical, electrical, and plumbing systems and other code-required work to make properties functional is appropriate within a restoration project.National Park Service — Technical Preservation Services
Reconstruction is defined as the act or process of depicting, by means of new construction, the form, features, and detailing of a non-surviving site, landscape, building, structure, or object for the purpose of replicating its appearance at a specific period of time and in its historic location.National Park Service — Technical Preservation Services