SPF (sprayed polyurethane foam) is applied to substrate as a liquid using a hose and nozzle. SPF first appears as paint, but when sprayed a combination of two substances join together and immediately begin to cure. Due to its chemical nature, SPF then expands into rigid foam up to 30 times its volume. As SPF expands it creates a durable, air-tight barrier system stopping leaks, cracks and holes from reducing building strength and energy efficiency.