The time, in minutes, contributed to the fire resistance rating by the noncombustible protection of...

The applicable standard is ASTM E119 , making option B correct. IBC Section 703.6 establishes a performance method for determining the number of minutes contributed by noncombustible protection applied to mass timber.

The methodology requires two otherwise identical assemblies to be evaluated using the procedures of ASTM E119 or UL 263 . Test Assembly 1 is tested without the protective covering. Test Assembly 2 incorporates the representative noncombustible protection, including its actual configuration, attachment details, joint treatment, accessories, and other relevant installation conditions. The protection contribution is then calculated by subtracting the fire-resistance time of the unprotected assembly from that of the protected assembly.

ASTM E119 is specifically designed to evaluate fire endurance of building construction and structural assemblies under standardized fire exposure. ASTM D3498, by contrast, is an adhesive specification referenced by the IBC for sealing certain mass timber interfaces. The other standards listed are not the prescribed comparative fire-resistance test for this determination.

References/Topics: 2021 IBC Sections 703.6 and 722.7.1; ASTM E119; UL 263; determination of noncombustible protection time contribution.

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