Douglas Fill and Fix Foam is an easy to use, polyurethane based expanding foam for general construction and home improvement applications. It's ideal for filling large, irregular or awkward gaps where the foam will expand to completely fill the cavity. This foam can also be used for fixing window and door frames and boards, insulating between brickwork and cladding, around ductwork and through cavities carrying pipes and cables. It can be used as a joint backing material and is suitable for use with all types of sealants. The 750ml can is a convenient size for most tasks.