Trex® Protectâ„¢ Joist Tape and Beam Tape and Trex® RainEscape® Deck Drainage System are two key decking moisture management systems. Trex Protect helps protect deck frames - wooden joists and beams - from the harmful effects of moisture, and Trex RainEscape uses a network of troughs and gutters to create a useable living space beneath a deck by draining water away.