CertaSeam™ Roof Tape is composed of two waterproofing materials - an aggressive rubberized asphalt adhesive backed by a layer of slip resistant film. During application, the release paper on the back is easily removed allowing the tape to bond tightly to the roof deck. A roll of CertaSeam is 4 inches wide and comes in a 75 foot length with one roll covering a 25 square foot area. The rubberized asphalt layer in CertaSeam Roof Tape seals around fasteners protecting the roof from leaks caused by water back-up behind ice dames or from wind-driven rain. The membrane forms water-tight overlaps and in addition to asphalt shingles it also protects under slate, tile, cedar shakes or metal. CertaSeam Roof Tape uses the same trusted techology of Grace Vycor™ Ice & Water Shield® roofing underlayment which has a proven track record of more than 45 years protecting roofs. There is no need for heat or special adhesives when installing CertaSeam since the self-adhesive membrane bonds firmly...See Moreto the roof deck without them. CertaSeam meets certain FORTIFIED Roof requirements. See Less