How to Build a Waterproof Exterior Wall

Smooth the exterior wall of a basement block wall with an electric concrete grinder. Wash the wall with a pressure washer and allow to dry thoroughly. Do this to ensure a waterproof coating applied will adhere to the blocks when you‘re ready for the coating of plasticlike material or asphalt and rubber to be applied.

Rent a trencher to dig a ditch along the foundation wall. Install perforated PVC pipe that is 5 inches in diameter in this ditch to channel rain away from the foundation walls into the soil. Add gravel over the pipe and pack dirt on top of the gravel.

Apply a high-quality waterproofing that is rubbery, such as hot asphalt that contains rubber, so the water barrier over the exterior blocks will not crack.

Check the interior wall space for waterproofing steps needed. Break open a couple of places along the basement interior wall with a handheld jackhammer if the concrete floor is already in place. The interior block wall -- before the concrete floor is poured against it-- should have a PVC perforated pipe along its bottom that is placed on top of house footing. Use pipe that is 3 inches in diameter.

Drill weep holes along the bottom of the interior wall into the block cavities with an electric drill. Place these weep holes every 5 inches or so about 3 inches above the finished floor. Spray a heavy coating of waterproofing material that is asphalt and rubber or plastic, similar to what's used on the house exterior.

Add a plastic sheet on the entire wall as a vapor barrier with a second sheet over the first, ensuring trapped moisture will travel downward to the floor level and not remain on the wall surface. Staple the upper edges of both sheets of plastic to wooden house framing. Picture the wall's moisture as traveling to the floor and seeping down to the horizontal drain and on into the dirt.

Add gravel on top of the interior PVC drain pipe to hold it in place. Place this pipe to channel rain water coming into the blocks during a rainstorm, for example, directly into the ground. Install metal grid over the gravel added on top of the drain system and pour concrete flooring.

Finish the basement interior walls with a specialized basement wall system for living space. Keep in mind that wood framing and paper on drywall supports mold growth, and mold is a known health hazard. Install factory-engineered panels, as one choice, that is constructed of rigid foam insulation. Use engineered panels that are clad with cement board under a vinyl surface.