Mixed Fire Caulks

Q: In the past our hospital has used different brands of fire caulk on the same fire wall assembly. The fire caulk is two different brands and different colors and surveyors have stated that we cannot have “mixed” caulk. Where in the Life Safety Code does this say we cannot mix fire caulks?

A: There is no specific Life Safety Code reference that speaks to this, but the surveyors are correct. It has more to do with the UL listing of the fire-stop assembly where the mixed fire caulks are used. A proper fire-stop system is an assembly and must comply with the UL listing that it was tested to. For example; to seal a penetration in a fire-rated wall, the UL listing will identify what type of fire caulk to use, what material it is permitted to be used on (i.e. gypsum board or cement block), and how to apply it. The UL listing is typically specific to the brand of fire caulk material used. This is because the manufacturers pay to have Underwriter’s Laboratory test the assembly and the resulting UL listing is specific to their brand of fire caulk. There is no UL listing for when you mix the different brands of fire caulk on the same assembly. Will it work? Most likely it will, but it does not meet the UL listing of that particular assembly. This is why there is a movement in the industry to have the installers who install fire-stop materials be certified to do so. Education is needed so the installers fully understand how to properly apply the products.