Analytical methods for determining fire resistance of timber members

Abstract

The fire resistance ratings of wood members and assemblies, as with other materials, have traditionally been obtained by testing the assembly in a furnace in accordance with ASTM International (ASTM) Standard E119 �Standard test methods for fire tests of building construction and materials�, International Organization for Standardization (ISO) Standard 834 �Fire-resistance tests-Elements of building construction�, and similar standards. In the U.S., these ratings are published in listings, such as Underwriters Laboratories Fire Resistance Directory, Gypsum Association�s Fire Resistance Design Manual, American Wood Council�s Design for Code Acceptance publications, and those in building codes. The ratings listed are limited to the actual assembly tested and normally do not permit modifications such as adding insulation, changing member size, changing interior finish, or increasing the spacing between members. Code interpretation of test results sometimes allows the substitution of larger members, thicker or deeper assemblies, smaller member spacing, and thicker protection layers, without reducing the listed rating.