When the joists cantilever past a beam, separate pieces are installed on each side of the beam, with each sloped to direct water to a gutter on the inner face and reinstallation of decking on an existing home. Products that are installed above the joists include DEK Drain and RainEscape. DEK Drain.

While composite decking does not need much work in the way of maintenance, you should still care for your deck. While composite decking is designed to resist water and the rot associated with wood decking, you should still do what you can to minimize standing liquid. Rework the deck to promote drainage. Redirect

The RainEscape deck waterproofing system, shown below, is an example of a membrane-and-downspout system. A number of recently introduced under-deck ceiling systems use corrugated aluminum or plastic panels designed to catch water that drains through decking and channel it away from

Another possibility would be an IRMA type roof construction - basically a roofing membrane under foam board insulation with a walkable stone or paver (usually) surface on top. However, unless deck surface could be tilted a bit for drainage you would not get away from the stangant water issue, plus

RainEscape Drainage System. A unique under-deck drainage system a network of troughs and gutters keeps rain, spills and snow melt from dripping through elevated deck boards, creating a dry patio area on the ground level below. Protect Joist and Beam Tape

The wood on my deck is too tight, so water isn't draining. I don't want to drill drainage holes if i don't have to. If, on the other hand, the decking material is a composite, the boards should have been installed with the proper spacing from the start, and your best bet is to take them up and re-install with the

Water drainage systems allow you to comfortably use the space under a high deck. The one shown here, RainEscape by the company, is simple to install, as long as you are careful to seal every possible leak with the system's special tape. RainEscapes installs on top of the joists, prior to installing decking.