One-part, neutral-curing silicone sealants exhibiting superior performance in applications where sealing openings in walls and floors are needed to control the spread of fire, smoke, toxic gasses, and water during fire conditions. It reacts with atmospheric moisture to form a tough durable seal that will adhere to most building substrates without the use of primers. It does not contain asbestos or PCBs. May also be used to seal vertical and horizontal joints between metals, masonry, concrete and other common construction materials. It is specially designed for use in static or dynamic joints. The low-modulus (+ 50% allowable joint movement) characteristic minimizes strain on the substrate surface and the elastomeric quality allows excellent recovery from extension and compression cycling.