10.036 Frequency of Testing Thickness for SFRM

Q IBV 1704.10.3.1 references ASTM E605 for thickness testing and E605 uses a frequency of testing, “at one bay or 10,000 sq. ft. of floor area”, but 1704.10.3.1 call for four tests on floor decking per 1,000 sq. ft. and 25% of the other proteced elements per floor. Is this a contradiction, and which frequency should be used?

— Unknown

A 5/08 – Response prepared by Terry Egland, a principal at Testing Engineers, Inc. and a registered engineer in California

The IBC uses E605 for thickness determination but has wording that supersedes E605 on the rate of testing. E605 conducts thickness testing at a rate of one bay per floor or one bay for each 10,000 sq. ft., whichever provides the greater number of tests. On the other hand, IBC 1704.10.3.1 would have the inspector take the average of “not less than four measurements for each 1,000 sq. ft. of sprayed area for floor decking and 25% of the other protected elements per floor. With such a conflict we refer to IBC 102.4 “Where differences occur between provisions of this code and referenced codes and standards, the provisions of this code shall apply.”

A sample Operating Procedure follows:

Sprayed fire-resistive material (SFRM) thickness, applied to the listed members whall be determined in accordance with ASTM E605.

For every 1,000 sq. ft. of SFRM applied, four measurements shall be taken in accordance with ASTM E605 and averaged for determination of the thickness.
NOTE:  The number of tests per square footage differs from ASTM E605.

Thickness shall be determined on 25% of the members on each floor in accordance with ASTM E605.
NOTE:  The number of tests per floor may differ from ASTM E605.