Design Tools for Assemblies

Many sources are available for identification and selection of tested fire-resistance rated assemblies, including testing laboratories, evaluation reports, manufacturer's technical literature and industry publications. Fire-resistance rated wood-frame assemblies can be found in listings contained in such publications as:

▶ American Wood Council Design for Code Acceptance (DCA) 3 - Fire Resistance-Rated Wood-Frame Wall and Floor/Ceiling Assemblies

▶ Underwriters Laboratories (UL) Fire Resistance Directory

▶ Intertek Testing Services’ Directory of Listed Products

▶ Gypsum Association’s Fire Resistance Design Manual

Fire-resistance rated assemblies may also be selected from one of the prescriptive assemblies provided in IBC Section 721 based on ASTM E 119 or UL 263 test results, or by calculating an assembly’s capacity using IBC Section 722. AWC DCA3 is also helpful in determining the fire-resistance rating of wood-frame wall and floor/ceiling/roof assemblies, and is available free at www.awc.org.

To permit use of “non-listed” assemblies, IBC Section 722.6 also recognizes a methodology for calculating the fire endurance of load-bearing and non-load-bearing wood assemblies (floor, wall, ceiling and roof assemblies) through a calculation methodology called Component Additive Method (CAM). CAM was developed in the early 1960s by the Fire Test Board of the National Research Council of Canada and validated through full-scale wood-framed assembly fire tests.

CAM calculates fire endurance to equal the sum of:

▶ the contribution of the fire exposed membrane,

▶ the time to failure of the framing members, and, if applicable,

▶ additional protection due to the use of cavity insulation or reinforcement of the membrane.

Section 722.6 contains the procedures by which fire-resistance ratings of wood assemblies can be established using this calculation method. AWC’s publication DCA 4 – Component Additive Method (CAM) for Calculating and Demonstrating Assembly Fire Resistance provides a history of the method and an in-depth explanation of its use and application.