AF JOINT is a special insulator designed to protect expansion joints against fire. Every building (and every fire compartment) needs intermediate spaces in order to contain the effect of natural dilatations normally due to temperature and occasionally to load changes. These gaps represent solutions of continuity in the fire resistance and can jeopardize – if the joint is not properly workmanlike protected – the fire prevention of a whole compartment. AF JOINT consists of a highly fire-resistant material which was subjected to a special treatment on both sides, thus allowing the fireproof mattress to resist the temperature of the STD curve for at least 180 min (EI 180) as provided for by the standard UNI EN1366-4.