Steel Design Series SDS-6

Part 6 – ULC and cUL Thin-Film Intumescent Coatings
Fire Rated Designs

George Frater, Canadian Steel Construction Council

Part 6 (SDS-6) contains a summary of fire-rated designs using thin-film intumescent coatings, an alternative fire-protection method to spray-applied fire-resistive materials (SFRM – summarized in CISC Steel Design Series Part 1, SDS-1). Tables of ULC and cUL fire-rated designs are provided for floor assemblies, and wide-flange and hollow structural section (HSS) columns.

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Description

Part 6 (SDS-6) contains a summary of fire-rated designs using thin-film intumescent coatings, an alternative fire-protection method to spray-applied fire-resistive materials (SFRM – summarized in CISC Steel Design Series Part 1, SDS-1). Tables of ULC and cUL fire-rated designs are provided for floor assemblies, and wide-flange and hollow structural section (HSS) columns.

Intumescent coatings are paint-like materials applied to structural steel with a typical thickness of 1 mm to 3 mm. When a fire occurs, the coating changes dramatically from a relatively thin film to a meringue-like insulating ash with a thickness of 50 to 100 mm or more. It is the intumescent ash that insulates and protects the steel from fire. Intumescent coatings are traditionally more expensive then SFRM but provide many benefits, including lighter weight per surface area protected, durability, aesthetic appeal for exposed steel, and good adhesion.