After major storm events, GAF Extended Dry-in Membrane helps to provide premium, long-term protection against damaging roof leaks and may be left exposed for up to 12 months, if necessary, until your new GAF roofing system is installed. In addition, it may be used as a leak barrier in your new GAF roofing system, as long as the new roofing system is installed within one year of membrane installation. For use only on roofs with slopes of 2:12 or greater.