When rehabilitating larger buildings, significant corridors should be preserved where possible. Code required changes should be made in such a manner as to preserve important features and finishes.

PRESERVATION
Tech Notes

HISTORIC INTERIOR SPACES
NUMBER 3

Preserving Historic
Corridor Doors and Glazing
In High-Rise Buildings

Chad Randl

Introduction

Historic office building corridors are often rich in distinctive features and materials. Glass door panels with gold leaf lettering, glass transoms and sidelights, woodwork and wainscoting all provide a physical connection to the way business was conducted in the late 19th century. Moreover, they display a level of detail, and quality of material and craftsmanship that are rare in new construction. Some of the same characteristics that make historic corridors significant and unique, however, may present a challenge to their sensitive rehabilitation.

   A primary difficulty lies in bringing historic features and materials "up to code." Because successive building regulations are rarely applied retroactively, a historic structure may be decades -- or even a century -- out of step with current life safety standards. When such a building undergoes a major rehabilitation or change in occupancy classification, the owner is usually required to bring the structure into compliance with modern codes written primarily for new construction. Among other provisions, current building codes often require that assemblies and materials provide a specified level of fire resistance. Historic doors and glazed transoms and sidelights are common corridor features that are unlikely to meet such resistance ratings.

   Building code enforcement has traditionally favored replacing existing materials and assemblies with new construction of known fire rating. In recent years, however, regulatory and technical solutions have better reconciled historic features with life safety and building code requirements. Rehabilitation provisions and equivalency and performance-based standards give building officials increased flexibility in determining how existing historic construction can meet current requirements. Meanwhile, manufacturers and designers have introduced new materials and assemblies that are more fire resistant. This Preservation Tech Note discusses some of the techniques applied when historic office corridor features are modified to meet modern safety standards. The conversions of two early skyscrapers in Chicago for new functions illustrate ways of complying with fire regulations while retaining original materials and assemblies.

Building Codes and Corridors