Deck Flash Post and Ledger Board Flashing is a flexible polyethylene waterproof flashing with a super grip rubberized asphalt self-sticking adhesive. Use to block moisture from damaging posts, apply to post at grade allowing at least 1″ above grade, deck joists and ledger boards. Prevents wood rot and decay caused by water accumulating under the deck boards and extends the life of the deck. Can be applied with temperatures of 35 F (Fahrenheit) and above. Can be used as a corrosion barrier between ACQ, CA-B, or ACZA treated lumber and metal surfaces. Easily installs by cutting to desired length, center over joist, remove paper and firmly press into place. This product re-seals around decking screws insure water proofing. Thickness: 40 Mm.