Weatherproof your deck from moisture with our self-adhesive, non-skid deck flashing tape. This butyl-based tape is designed to shield joists and beams and ledger board from moisture that can lead to wood rot and decay and the loosening of screws and fasteners. Today?s high-performance composite deck boards, like those of Trex, are warranted to last 25-50 years. But, research shows that the deck substructure can begin to spilt, rot and decay in as little as 8-10 years. To protect an average size deck measuring 7.2m x 3.6m will require approximately 5 rolls of Trex Protect Joist Tape. For less than a $300 investment, your deck substructure can last as long as the decking it supports.