ExoAir LEF

Low-Expanding Polyurethane Foam

ExoAir® LEF is a single-component, CFC-free, all-season, high performance, gun-grade polyurethane foam that performs as a thermal barrier. ExoAir LEF is part of the Tremco T3 building envelope transition toolbox.


  • The ExoAir LEF is best suited around window and door frame joints but can also be used as an effective joint filler in hidden applications
  • LEF is most commonly used as a thermal and sound barrier
  • The product can be installed in temperatures ranging from 14 to 95° F (-10 to 35° C)