New! Presenting a DCI Breathable/Water-Proof Underlayment! Max. Protection! SmartRoofDeck UnderLayment- SRD-30” Vented Roll Size and Coverage: 30” x 164 feet yields, 402 square feet of SRD-30 Underlayment It ventilates attic areas while waterproofing above deck areas from condensation (That covers over 12 sheets of plywood!)