A beam requires a mil thickness of 65 mils for TFIFRM. What is the lowest allowable average mil thickness for the beam?

The requirement for a beam to have a thickness of 65 mils for the specified fireproofing application means that this measurement is essential for the material to effectively provide the necessary fire resistance based on performance criteria. In the context of spray-applied fireproofing, the average thickness typically needs to meet or exceed specific minimum requirements to ensure reliability and safety in fire protection.

In this scenario, the lowest allowable average mil thickness should match the required thickness. If the average thickness were to be less than the required thickness of 65 mils, it could compromise the fireproofing effect, essentially rendering it inadequate in a fire event. Therefore, having an average thickness of 65 mils aligns with maintaining the integrity and performance of the fireproofing system.

The other choices present thicknesses below 65 mils, which would not provide the level of fire resistance mandated for the beam's protection. For any successful application of fireproofing, adherence to the specified thickness is crucial, making 65 mils the proper choice as the lowest allowable average mil thickness for that beam.