Waterproofing basement walls can be a difficult procedure, but there are a few tips to make the project more successful. Before beginning any work on the interior walls, make certain that rainwater runoff is sufficiently drained away from the basement area. Patch all cracks and holes in the basement walls must before applying a waterproof coating. If possible, cover the entire wall with a thin layer of hydraulic cement to further seal out moisture. An application of crystalline waterproofing material followed by two coats of waterproof paint usually produces the best results.
Successfully waterproofing basement walls often requires certain preventive measures to be taken outside of the structure. Check that all stormwater runoff is directed away from the basement area by installing roof gutters and downspouts. A downspout extension pipe may be needed to empty the gutters away from the structure. Another way to divert runoff is to gently slope the soil away from the basement area. It may also be necessary to install a French drain system alongside the foundation to collect excess water.
The specialized coatings used for waterproofing basement walls work best on clean, smooth surfaces. Old paint should be scraped, sanded, or removed to provide the best possible seal. Holes and cracks must be filled with an epoxy patch material before applying coating. Force the repair material into the void with a putty knife to prevent air pockets. Allow the repairs to cure completely before applying the waterproof coating.
Applying a thin layer of hydraulic cement to the entire surface will help seal out moisture when waterproofing basement walls. This material expands as it dries and covers tiny holes and irregularities in the surface. Hydraulic cement may be used alone or with a crystalline waterproofing material. This specialized material is a penetrating sealer that works its way into the pores of the wall to block out moisture. Crystalline waterproofing material works best when applied to uncured hydraulic cement.
After all of the walls have been properly prepared, apply two coats of latex waterproof paint to the entire surface. Latex waterproofing paints generally adhere better to moist surfaces. Lightly mist the walls with water before and after each coat of waterproof paint. Use a stiff brush to spread the paint in a circular motion and allow at least 24 hours of drying time between each coat. Use extra paint at the corners and base of the walls to avoid gaps in coverage.