Under-Deck Drainage Roundup | Professional Deck Builder .
Feb 27, 2015 . 's RainEscape includes plastic trough sheets and downspouts, as well as a special flashing tape and caulk. The trough sheets are stapled to the top of the joists and drape between them. Water falls between the deck boards into the troughs, and drains to downspout funnels at the end of each joist bay