Digging a big hole in the ground for a foundation is an open invitation for water intrusion. Some people live with this reality every time it rains. In other cases, basements can stay pretty dry until a 50- or 100-year flood event comes along. Regardless of the age of the home or the location, there are a few principles that apply to every home.
Preventing water intrusion starts on the exterior. Proper grading of the soil around the home and good drainage for surface water runoff are critical. When performing a home inspection, I stress the significance of the grade near the foundation. In a perfect world, the land adjacent to the foundation should slope away and downward approximately 6” in the first 10 feet. Sometimes this can be done by simply adding topsoil.
Where the topography does not allow for proper grading, sometimes a swale can be constructed to help divert water away from the home. A swale is simply a shallow ditch that helps channel water away from the building. If a swale isn’t feasible, installation of a perimeter drain system, or French drain, may be required. This type of system requires excavation and burial of a perforated pipe on either the exterior or interior of the foundation. When the installation occurs inside the basement, a sump pump system is generally included.
Another big offender in the list of causes for moisture in the basement is improper installation of gutters and downspouts. Occasionally I inspect a home with no gutters at all. Rain dripping against the foundation is never a good thing. Not only can the constant dripping cause water to work its way in through cracks in the foundation, the water also splashes onto siding and trim and usually results in deterioration and rot. If your home already has gutters and downspouts, you’re a step ahead of the game. Just make sure you have long enough downspout extensions so water gets directed several feet away from the foundation.
Foundation cracks can be another contributing factor to water infiltration. Just about every type of foundation has imperfections that can become openings for water. Older stone foundations develop cracks and gaps in the mortar. Newer concrete foundations routinely develop small cracks from differential settlement. Spot repointing in masonry and sealing up concrete cracks should become part of your regular maintenance and upkeep.
A little effort goes a long way in keeping your basement dry. Next time we get a good rainstorm, put on your foul weather gear and take a walk around your home. Think about some adjustments that could be made to your grading, gutters and downspouts or foundation that could help keep water away from your home. If in doubt, call in a professional landscaper or dry basement contractor. They almost always can come up with a solution to help keep your basement dry.