On June 6, 2016, the National Park Service (“NPS”) released an updated Preservation Briefs 41: The Seismic Rehabilitation of Historic Buildings. Last updated in 1997, the brief outlines the vulnerability of historic buildings and the resulting danger posed to human lives.
The revised edition includes expanded sections on achieving seismic retrofit and preservation, evaluating significant historic features and spaces, developing a seismic rehabilitation plan, cost and implementation, remediating seismic deficiencies, and more.
NPS stressed four important preservation principles to keep in mind when undertaking a seismic historic preservation project:
- Historic features and materials, both structural and nonstructural, should be preserved and retained, not as museum artifacts, but to continue to fulfill their historic function to the greatest extent possible, and not be replaced wholesale in the process of seismic strengthening.
- If historic features and materials are damaged beyond repair, or must be removed during the retrofit, they should be replaced in kind or with compatible substitute materials. If they must be removed during the retrofit, they should be removed carefully and thoroughly documented to ensure they can be properly re-installed in their original location.
- New seismic retrofit systems should work in concert with the inherent strengths of the historic structural system, and, whether hidden or exposed, should respect the character and integrity of the historic building, be visually unobtrusive and compatible in design, and be selected and designed with due consideration to limiting the damage to historic features and materials during installation.
- Seismic work should be reversible whenever feasible to allow its removal for future installation of improved systems as well as repair of historic features and materials.