Suppose the roof framing of a building has 24 columns and 42 beams. How many members must be tested for SFRM thickness?

In order to determine the number of members that must be tested for Spray-Applied Fire-Resistive Material (SFRM) thickness, it's important to understand the testing requirements laid out in the relevant codes and standards. These standards typically prescribe that a specific percentage of structural members need to be tested to ensure proper fireproofing application.

In this scenario, there are a total of 24 columns and 42 beams. The testing approach often focuses on representative samples that cover both types of members, with an emphasis on ensuring that both columns and beams are adequately assessed.

The correct answer indicates a testing requirement that likely aligns with this approach, considering the overall number of structural elements present (24 columns + 42 beams = 66 total members). From the total, the testing protocols might outline that a certain number of these representatives should be sampled—hence arriving at the number indicated in the correct answer.

Thus, the answer reflects a systematic and methodical approach to ensuring the fireproofing is adequately applied across various structural components to maintain the building's integrity during a fire event.