A column requires a mil thickness of 65 mils for TFIFRM. What is the lowest allowable mil thickness for an individual thickness determination?

In this context, the question refers to the evaluation of spray-applied fireproofing on a column, where a specified thickness of 65 mils is required for proper fire protection. The minimum allowable thickness for individual measurement would generally be determined based on a specific percentage of the required thickness in order to ensure that the fireproofing maintains its effectiveness.

The lowest allowable thickness for an individual determination is often set as a practical threshold. This threshold typically ranges around 80% of the specified required thickness. For a requirement of 65 mils, calculating 80% yields 52 mils (0.8 x 65 = 52), which is the threshold below which the fireproofing would not meet the necessary standard.

Therefore, the correct choice reflects that 52 mils is the nearest value that allows for a valid thickness determination, ensuring the fireproofing would still provide adequate fire resistance while upholding industry standards and guidelines.