How many TFIFRM thickness determinations are required for a W-shape column?

For determining the thickness of spray-applied fireproofing on a W-shape column, the guidelines specify that a minimum of 24 thickness determinations are required to ensure accuracy and compliance with safety standards. This number helps account for variations in the coating application and provides a more representative sample across the surface of the column.

Having 24 measurements allows for a statistical approach to ensure that all areas receive the intended level of fire resistance, thus enhancing the structural integrity during a fire event. By taking multiple measurements, you can identify any inconsistencies in the application process and make necessary adjustments, ensuring that the fireproofing meets code requirements effectively.

The other options reflect numbers that are either insufficient or not aligned with the standard practices for thickness determination in fireproofing applications. Therefore, the requirement of 24 thickness determinations is based on best practices and ensures that the fireproofing is both effective and compliant with regulations.