The key to choosing the best basement waterproofing products is to determine the scope of the water problems, and based upon that investigation, to pick the products which match the issues being addressed. For example, different products are used to waterproof exterior and interior foundation walls. Also, waterproofing is relatively easy if the job is simply preventative, but if water is leaking into the basement, then the cause of the leak needs to be corrected before applying any waterproof paint or tar.
Selecting waterproofing products for new construction is much easier, since there is no damage to repair. A reputable building contractor should make certain that the property is graded so runoff goes away from the house, and that downspouts are in place to drain roof water at least 8 feet (2.44 m) away from the foundation. Depending on the depth of the water table in the area, footer drains and tiles may need to be installed at the base of the foundation, and a pump added if necessary. Also, the exterior walls can be treated with a waterproofing tar.
Treating an existing fixture can be much more involved. If the work is simply preventative, and the basement is not experiencing any leaks or moisture, then the best basement waterproofing products include exterior items such as adequate downspouts and window well covers, and interior waterproofing paint. These paints come in both oil and latex bases, and should contain an anti-mold agent. Waterproofing paint can only be applied to bare blocks, stone or concrete, so any existing paint must be removed.
If the basement is experiencing some water leakage, then the first step is to determine why and where the water is coming in. In the majority of homes, water seeps in through the joint where the wall and the floor meet. As water drains along the foundation, it pools into pockets, creating hydrostatic pressure which eventually forces the water through the joint. If this is the case, then the most important basement waterproofers are those which will drain the water away from the foundation. If there are no holes or cracks in the wall, then the only interior product that is needed is waterproofing paint.
Once the exterior issues have been addressed, a carefully examination of the cracks and holes in the interior walls is necessary to determine which basement waterproofing products to use. When cracks are less than 1/8th inch (3.2 mm), then either polyurethane or epoxy fillers will correct the problem. If a crack is larger, then it needs to be cleaned out and patched, preferably with epoxy fillers. These come in a variety of thicknesses, so read the labels to determine which filler is appropriate for the area. In general, the wider the crack, the thicker the epoxy filler should be.
One drawback to using epoxy basement waterproofing products is that they require more drying time. If the crack goes all the way through the wall, then there is a danger that the epoxy could leak out before completely sealing the area. In such a case, it is better to use polyurethane foam filler. Polyurethane fillers expand when water leaks into them, effectively filling the cracks and stopping the water leaks.
After the cracks have been filled, the last step is to apply a waterproofing paint to the interior walls. If the walls are somewhat porous, it might be advisable to use capillary waterproofing products. These paints can go on interior or exterior walls, and penetrate several inches into the concrete. When exposed to water, the paint forms crystals which close off minor cracks and capillaries.