The most typical cause of runoff is melted snow and rainwater that is not directed away from the house. Hydrostatic pressure forces the water through gaps or cracks in walls and footings. You can prevent runoff by making sure the ground outside your home slopes away from your house at least one inch (25 mm) vertically for every 12 inches (300 mm) of horizontal travel and that downspouts are not leaking or pooling near the foundation.
This problem shows signs as water moves through cracks in the walls or floors. Here, growths of mold and algae suggest a damp surface.
Groundwater swells when the water table has exceeded its high point. Soil surrounding your home is unable to hold the extra water, causing a consistent runoff problem. If you have a wet basement due to groundwater swelling, your basement will be wet for a long period after each storm and there may be water bubbling up from the joints between the wall and floor. Many homes are not constructed with protection from high groundwater, and it is very expensive to install a system to combat the problem.
Combating a Wet Basement
No matter if your basement is finished or you use it as just a storage room, it is important for the structural integrity of your home to combat a wet basement problem as soon as you discover it. Solutions to tackling a wet basement are plenty. The first step is trying to figure out the type of problem you are encountering. Then, check the grading around your home, downspouts for any leaks or pooling, and cracks in the driveway. Fix all of the problems you encounter as well as patching cracks in the basement walls and floors, as water in the home can cause mold problems as well as a wet basement.
Applying a Concrete Sealer
Sealers are available for coating basement walls and floors. They offer a quick waterproofing measure and can be decorated. They are easy to apply, provided you follow the manufacturer's guidelines. They can be applied to damp surfaces but any standing water should be removed.
Fitting a Polyethylene Membrane
An alternative to epoxy coatings is to use a polyethylene membrane. Although it holds back water, it may be necessary to install channels and a sump pump to collect and remove water from behind the membrane. Seek professional advice on whether this is required. Measure the surface area you need to cover and make sure you buy enough membrane for your needs.
Excerpted from Do It Yourself Home Improvement
© Dorling Kindersley Limited 2009