Everbuild pyro mate firesil everbuild prywe pyro mate silicone is a neutral cure elastic silicone sealant which conforms to bs 476 part 20 en1366 4 2006 for fire retardancy and has a fire rating of up to 4 hours in certain joint configurations acoustic rated to bs en iso 140 3 tested for air permeability to en13141 1 ventilation for buildings performance testing for components products for residential ventilation conforms to iso 11600 class f 25lm when tested to iso 9047 8339 and 1056