Preserving historic buildings

Protecting historic buildings is a challenge, but performance-based design concepts can help make the twin goals of historic preservation and reasonable fire protection a reality.

Many codes note that historic structures under construction or being repaired, altered, enlarged, restored, or relocated needn't comply with the code provisions. However, the authority having jurisdiction (AHJ) must determine that the building is reasonably safe and doesn't constitute a serious life safety hazard.

Although proposed changes have been submitted to include specific language for historic buildings, NFPA 101(R), Life Safety Code(R), doesn't contain specific provisions for them. However, the AHJ may modify the code when it isn't practical to bring a building into compliance with code requirements, as long as the level of life safety already provided is reasonable. Conditions that represent a serious threat to life must be mitigated, but the code allows some latitude in nonlife-- threatening situations because more effort and money may be needed to correct the physical limitations of an existing building than the increase in life safety would warrant.

Preserving historic characteristics

Although people think that performance-- based codes apply only to new construction, historic buildings present a perfect opportunity to apply performance-based design approaches to fire protection and life safety. While those who preserve historic buildings want to maintain their historic characteristics, they also want to provide a reasonable level of life safety, protect property, and minimize disruption to operations.

All historic structures have features worth preserving. In the United States, a good example is exterior doors in buildings from the Colonial period. Modern codes generally require that such doors swing in the direction of egress travel. However, this wasn't the case in Colonial America, and reversing the door swing will not only alter a historic characteristic, it could even create hazards if it results in a change in elevation outside the building.

To maintain a structure's historic characteristics, designers must be able to document that the structure provides a reasonable degree of life safety. For example, they may be able to calculate safe egress times to demonstrate that even though a door swings inward, it doesn't constitute a serious life safety hazard. Or they may be able to use design fire scenarios to demonstrate that a historic building's interior finish materials don't contribute to rapid fire growth.

A historic building might also be brought into compliance by imposing operating restrictions on its use, such as limiting occupant load. Where restricting occupant load isn't practical or doesn't result in code compliance, other restrictions may be imposed. In one building in which the door swings inward, the guide is required to announce that the doors swing inward before a reenactment of a Colonial-era trial and to stand by the door during the reenactment.

Fire protection systems may also be installed to compensate for architectural features that aren't consistent with modern codes, such as open stairways. Using computer fire models and other analytical tools, system designers may be able to demonstrate that problems such as egress deficiencies aren't a serious life safety hazard in buildings that have reliable fire protection systems.

It's often easier to install a fire protection system properly than it is to correct existing deficiencies, especially where the "deficiency" is historically significant. And installing fire alarms and sprinklers in buildings constructed before such technology became widespread is widely perceived as a means of preserving the structure for posterity. However, such systems should be installed carefully to avoid damaging the buildings fabric and to minimize the aesthetic impact on its architectural and historic features.

Additional requirements for protecting historic buildings can be found in NFPA 909, Protection of Cultural Resources, Including Museums, Libraries, and Historic Properties, and NFPA 914, Recommended Practice for Fire Protection in Historic Structures.

W. E. Kofffel, is president of Koffel Associates, with offices in Maryland, Connecticut, and Tennessee.

Copyright National Fire Protection Association Sep/Oct 1999
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