What is fireproofingin construction?

Start with the rating hours on the architectural code summary, then find the listed UL design referenced in the spec or on the drawings. Each design publishes thickness as a function of the member's W/D ratio, weight per foot divided by heated perimeter, so a light beam might need 1-7/8 inch where a heavy girder reaches the same rating at 1 inch. Never apply one thickness across the whole frame; sort members into thickness bands before pricing.

Because the cost driver is sprayed surface area, not weight. A light beam has nearly the same perimeter as a heavy one of the same depth, so a job full of light framing carries far more sf per ton, and a per ton plug will underprice it. Measure profile perimeter times length for each member, keep the thickness with the quantity, and the number defends itself at bid review.

After spray is complete, mechanical, electrical, and fire protection trades hang supports from the steel and knock material off, and inspectors will flag bare spots before ceilings close. Most fireproofing subs carry a patching allowance, commonly a few percent of the base sf or a return trip crew cost, and GCs backcharge trades that cause damage beyond it. Carry it as a visible line in the estimate so it is not a fight during the job.