Membrane Waterproofing for Wood Substrate

Clean the Floor

• You can waterproof a wood substrate floor beneath a shower or bathtub by installing a vinyl membrane to the floor’s surface. Before installing the membrane over a wood substrate floor, clean the floor surface of all dust and debris. Use a wet mop to pick up the loose dirt and allow the wood substrate to dry for a few hours before laying down the membrane.

Placing the Membrane

• Once the wood substrate dries, lay the vinyl membrane out over the area of the floor where the shower pan or the bathtub will be placed so the vinyl is roughly centered over the section. Smooth the vinyl membrane out as much as possible to remove wrinkles and bubbles from the surface and tape the edges of the vinyl down to the floor. If the membrane must be installed next to a wall, smooth the side of the membrane by the wall up the wall surface and tape it in place on the wall.

Cutting Around the Drain

• When installing membrane waterproofing over wood substrate, cut a hole in the membrane over the area in the floor where the drain for the shower or bathtub lies. Find the drain by moving your hand across the membrane and then make a cut into the membrane in the center of the hole. Trim the membrane in the area of the drain to leave only about 1/8-inch of liner overhanging the drain’s edge.

Securing the Membrane

• Before securing the rest of the membrane, create a waterproof seal around the drain by applying waterproof sealer beneath the edge of the membrane. Spread the sealer about an inch around the hole for the drain and press the membrane down into place on the wood substrate. Hold the membrane in place for approximately five minutes to get a good hold and then attach the rest of the membrane to the substrate by driving a nail through the membrane every two to three inches. Cover all nail heads with waterproof sealer.