Worldwide Leader in Firestop Technology - Our family of UL approved Metacaulk® Firestopping Products is specifically designed to fill voids in construction joints and around penetrations in fire-rated walls or floors. Many have intumescent properties and expand when exposed to heat, forming a high-strength insulating char. Metacaulk® products contain a combination of biocides that protect the product in both the cured and non-cured state against mold growth. Our intumescent firestop products comply with required environmental exposure testing of accelerated aging and high humidity, as per UL 1479 Fire Test of Through-Penetration Firestops. In the event of fire, Metacaulk® sealants will restrict the spread of flames, smoke, hot gases and water. Whatever your application, we provide the most cost effective products to fit your every need.