Joist Tape (Deck Flashing Tape)

Self-adhesive butyl tape applied to the tops of deck joists before decking installation. Prevents water from sitting in fastener holes and causing premature joist decay.

In Detail

Joist tape extends deck joist life by 2–3× by shedding water away from screw penetrations. Products like Trex Protect, G-Tape, and ZIP System Flashing Tape are commonly used. The tape's butyl adhesive self-seals around screw shafts. Apply it to the top edge of all joists, rim joists, and blocking before installing deck boards. Cost: typically $0.10–$0.20 per linear foot.

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