ISOCELL AIRSTOP FOAM is a specially formulated high density Pu foam designed for sealing of difficult areas such as pipe penetrations and openings, ideally suitable for masonry construction as well as timber frame; ISOCELL AIRSTOP FOAM is considerably denser than other non-airtight foams available on the market. Due to the composition of ISOCELL AIRSTOP FOAM better insulating properties are achieved then other PU foams. ISOCELL AIRSTOP FOAM can be used with Airstop window tapes around Doors and Windows to offer higher insulation properties and airtightness. Due to expansion and contraction as well as structural settlement particularly around openings such as doors and windows it is not recommended that it is used solely in these areas as a total airtight solution.