Everbuild fire foam b1 handheld aerosol everbuild evfire firefoam b1 handheld is a quick setting fire rated one part polyurethane foam it expands on application to yield up to 50 times the can contents and meets the extremely stringent requirements of the test criteria bs476 part 20 class b1 fire rated up to 4 hours in certain joint configurations once cured the foam can be cut sawn or plastered over after approximately one hour everbuild evfire fire foam b1 handheld aerosol 750ml