Fireproofing, Spray-Applied
CSI Division 07, Thermal & Moisture Protection
A spray-applied cementitious or intumescent coating applied directly to structural steel to insulate it from heat, giving the steel enough time before it loses structural strength in a fire for occupants to evacuate and firefighters to respond, distinct from [[concept-firestopping|firestopping]], which seals openings rather than coating the structure itself.
Why it matters
Unprotected steel loses much of its strength at fire temperatures far lower than most people expect, so the fireproofing's thickness, specified in hours of fire rating, is calculated for the specific structural member's size and the rating the code requires for that part of the building, not applied at a single standard thickness everywhere.
On a real project
A fireproofing subcontractor sprays cementitious fireproofing onto structural steel beams and columns to a thickness verified with a gauge at multiple points on each member, confirming it meets the two-hour rating the code requires for that structure.
Who this matters most to
A specialty fireproofing subcontractor applies the coating. A QA/QC Inspector verifies the applied thickness with a gauge before it's covered by other finishes.
Where this goes wrong
A fireproofing crew sprays a steel column to what looks like an adequate coating by eye but skips the gauge verification the specification requires. The shortfall isn't found until the fire marshal's final walkthrough flags visibly thin coverage at one beam's flange, and the crew has to strip and reapply fireproofing across the whole corridor's steel before occupancy can be granted.