How to Get Your Deck to Drain

Use slope when you build a deck onto your home. If the deck sits at the top of a hill or gentle slope that occurs naturally in the landscape by your house, you can slope the deck approximately ¼-inch per every foot of deck with the slope aiming down from the house. With this set-up, the water automatically flows off the front of the deck and away from the home’s foundation.

Remove the railings and flooring planks from the deck by removing the screws and nails that hold the components in place if the deck has no slope and water pools on the surface. If the wood is wet when you remove it, set the pieces in the sun to dry as you work.

Create slope to the deck by sanding down the joists from one side to the other, away from the house, creating a slope of approximately 1/8-inch for every foot. Check the slope of the joists by setting the end of a wood board of the same length as the joist at the higher end of the joist with a level on top, holding the board up at the other end until it sits level and then measuring the distance between the end of the level board and the low end of the joist to figure the slope. A deck that’s 8-feet across should have 1-inch of distance between the lower end and the board.

Roll a vinyl membrane, such as those sold as shower pan liners, out along the exposed studs of the deck. Staple the membrane to the first stud and let it hang down to create a trough 3 to 4 inches deep between the studs before stapling it to the next stud. Continue this pattern all the way across the deck, using more than one piece of vinyl if necessary.

Install a gutter at the low end of the deck using by screwing the gutter to the deck with the provided screws. Place the gutter so that the membrane troughs that direct the water end just above the top of the gutter. Attach a downspout at one end of the gutter and aim it away from the house.