What is the lowest allowed thickness for a tube column needing 1" of SFRM?

The lowest allowed thickness for a tube column requiring 1 inch of Spray-Applied Fire-Resistive Material (SFRM) is indeed 1 inch. This thickness requirement is established by building codes and standards to ensure that the fireproofing material adequately protects the structural integrity of the column in case of a fire.

The specification of 1 inch is derived from the need to provide sufficient insulation against heat, preventing the steel column from reaching critical temperatures that could lead to failure. While materials may have varying performance characteristics, the specified thickness guarantees a standard level of protection, facilitating consistent building practices and ensuring safety during a fire event.

Other thickness options listed, such as ¾ inch, 1-¼ inch, and 1-½ inch, do not meet the required minimum thickness necessary to achieve the desired fire-resistive performance, thus making 1 inch the appropriate choice for compliance with fire protection standards.