deck flash barrier 3″ x 75′ roll. When applied to the top of deck joists, deck flash barrier creates a waterproof membrane that prevents wood rot and decay caused by the accumulation of water under the decking boards. deck flash barrier’s new super grip adhesive can now be installed at temperatures down to 25 f. deck flash barrier self-seals around screws and nails, blocking a primary pathway for water infiltration into deck joists thus preventing wood rot, deck flash barrier creates a physical barrier that prevents corrosion of the metal surface caused by contact with acq ca-b, and acza treated lumber. Deck flash barrier can be used to protect metal flashing, joist hangars, the deck plates, sill plates and anywhere treated lumber is used.