Four Approaches to the Treatment of Historic Properties
There are Standards for four distinct, but interrelated, approaches to the treatment of historic properties—preservation, rehabilitation, restoration, and reconstruction.
Choosing an appropriate treatment for a historic building or landscape is critical.
Preservation focuses on the maintenance and repair of existing historic materials and retention of a property's form as it has evolved over time.
Rehabilitation acknowledges the need to alter or add to a historic property to meet continuing or changing uses while retaining the property's historic character.
Restoration depicts a property at a particular period of time in its history, while removing evidence of other periods.
Reconstruction re-creates vanished or non-surviving portions of a property for interpretive purposes.
The choice of treatment depends on a variety of factors, including the property's historical significance, physical condition, proposed use, and intended interpretation. Historic buildings are used as an example below. The decisionmaking process would be similar for other property types.
Relative importance in history. Is the building nationally significant? Is it a rare survivor or the work of a master architect or craftsman? Did an important event take place in it? National Historic Landmarks, designated for their "exceptional significance in American history," or many buildings individually listed in the National Register often warrant Preservation or Restoration. Buildings that contribute to the significance of a historic district but are not individually listed in the National Register more frequently undergo Rehabilitation for a compatible new use.
Physical condition. What is the existing condition, or degree of material integrity, of the building prior to work? Has the original form survived largely intact or has it been altered over time? Are the alterations an important part of the building's history? Preservation may be appropriate if distinctive materials, features, and spaces are essentially intact and convey the building's historical significance. If the building requires more extensive repair and replacement, or if alterations or additions are necessary for a new use, then Rehabilitation is probably the most appropriate treatment.
Proposed use. An essential, practical question to ask is: Will the building be used as it was historically or will it be given a new use? Many historic buildings can be adapted for new uses without seriously damaging their historic character. However, special-use properties such as grain silos, forts, ice houses, or windmills may be extremely difficult to adapt to new uses without major intervention and a resulting loss of historic character and even integrity.
Mandated code requirements. Regardless of the treatment, code requirements will need to be taken into consideration. But if hastily or poorly designed, code-required work may jeopardize a building's materials as well as its historic character. Thus, if a building needs to be seismically upgraded, modifications to the historic appearance should be minimal. Abatement of lead paint and asbestos within historic buildings requires particular care if important historic finishes are not to be adversely affected. Finally, alterations and new construction needed to meet accessibility requirements under the Americans with Disabilities Act of 1990 should be designed to minimize material loss and visual change to a historic building.
The Guidelines for the Treatment of Historic Properties illustrate the practical application of each treatment to historic properties.
The Guidelines for the Treatment of Cultural Landscapes apply the treatment standards to historic cultural landscapes.