Fire-Resistive Construction, Part 3
By Ronald L. Geren, RA, CSI, CCS, CCCA

Editor’s Note: This is the final part of a three-part series
In some cases, ratings for these items are not required, provided they comply with specific requirements. For example, windows and doors within fire-resistance-rated exterior walls need not be rated provided the total area of the openings does not exceed the allowable area based on distance from the property line. Another example is steel electrical boxes. Electrical boxes, 16 square inches or less in area, are permitted in fire-resistance-rated assemblies provided that no more than 100 square inches are within 100 square feet of wall area. They must also be separated from boxes on the other side by either a distance of 24 inches, listed putty pads, approved insulation, solid fire blocking, or other listed methods.

Many assemblies, both proprietary and generic, have been tested, and the reports are readily available. Chapter 7 of the IBC includes prescriptive requirements for some common assemblies, as well as provisions for calculating fire resistance to allow some flexibility. The Gypsum Association publishes GA-600, Fire Resistance Design Manual, that provides ratings for wall, floor, roof, column, and beam protection utilizing wood or metal studs and gypsum board. Another excellent resource is UL's annual Fire Resistance Directory. This 3-volume set provides fire resistance ratings for hundreds of assemblies, including penetrations and joints.

Fire resistance is a key element of the building code's intent to provide "safety to life and property from fire." If you're a designer, specifier, product representative, or contractor, you need to be aware of the requirements for fire resistance. Most jurisdictions will insist that tested or listed assemblies be used and specifically identified in the contract documents. Care must be taken in selecting and specifying materials and products used in fire-resistance-r ated assemblies. Skilled labor must be utilized when constructing fire-resistance-rated assemblies, including the penetrations, which require more attention than just applying "red putty" around the item. In the end, the assembly you design, specify, provide, or install, may be the one thing that prevents a tragic event. Just recall the aftermath of September 11, 2001. The fire resistance of the World Trade Center was heavily scrutinized at all levels, and although the event far exceeded what anyone could have imagined, the outcome may eventually have a significant impact on fire-resistive construction in all future construction, big or small.

Ronald L. Geren, RA, CSI, CCS, CCCA is the specification writer and code reviewer for the Phoenix Office of Gould Evans He is a 1984 graduate of the University of Arizona, and has held various technical and managerial positions for military, state, and private agencies. To comment on this article, suggest other topics, or submit a question regarding codes, contact the author at ron.geren@gouldevans.com