JoistTape Self-Adhesive Joist Barrier Tape adheres to the top-side of deck joists prior to installing deck boards. Also for use around deck support posts as well as over ledger boards. This self-adhesive joist barrier tape is a malleable polyethylene water-resistant lumber flashing material, utilizing a rubberized asphalt mastic adhesive. When this tape is installed over joists, it produces a water resistant barrier which helps prevent joist decomposition and wood rot. Joist rot is caused through trapped moisture which remains in contact with treated and untreated wood deck framework and the above decking material. Wood decay can easily also take place when deck anchoring screws penetrate the deck boards, piercing the joist sub-framing underneath. The application of joist barrier tape will also seal around decking screws combating the invasion of water and moisture. The tape has a super grip rubberized asphalt adhesive and is a self-sealant around deck screws which will obstruct the primary pathway for water infiltration into deck joists. JoistTape water-proof barrier tape can maximize the lifetime of your brand new patio or renovation project. Once this tape is applied between ACQ, CA-B or ACZA treated lumber-as well as metal surfaces such as galvanized steel and aluminum joists-a physical buffer is in place which reduces the deterioration of wood and corrosion of the steel surface caused through contact with chemical substances in treated wood. Color: Black.