Waterproof sealant and adhesive for emergency repairs EMERGENCY WaterStop is a gun-grade, wet sealant that combines the best of silicone and polyurethane properties. This single component, Silyl-Terminated-Polymer (STP) is easy to gun and tool in all weather conditions. Seals and bonds to most building materials – even when submerged in water – producing a durable, high performance, high movement elastomeric sealant. The ability to install EMERGENCY WaterStop underwater and in adverse conditions eliminates many weather-related construction delays and makes it possible to dry in buildings being damaged by active water leaks. EMERGENCY WaterStop adheres to most surfaces and is immediately waterproof.