Avoiding wet basement can be dirt-cheap

Inspector's Eye

April 15, 2001

One of the most predictable comments made in a home inspection report is that "water runoff is inadequate next to the exterior of the house."

Poor water runoff exists at most houses, but is commonly ignored by homeowners. This is unfortunate, because it is among the leading preventable causes of wet basements and foundation problems.

Most homeowners dutifully maintain their lawn, prune the shrubs, rake leaves and mulch the beds. These are all essential if you want a well-groomed property.

But in terms of their physical effect on the house, none of these counts for much compared to the task of periodically adding topsoil around the home's perimeter to compensate for soil settlement that gradually occurs.

The addition of topsoil builds the soil surface back to where it should have been all along - gently sloping away from the house.

What constitutes poor water runoff may not be clear to some homeowners. Runoff may seem fine as long as any accumulated rainwater disappears within a short time after the rain stops. But where the water goes when it disappears can be important.

If the surface of the ground within a few feet of the house is flat or, even worse, slopes down toward the house, consider runoff to be poor.

Without a properly sloping soil surface, rainwater will not naturally run away from the house, rainwater will collect next to it and, if the rainwater soaks into the ground there, trouble begins.

The water will saturate the backfill around the foundation, often as deeply as the footing at the base of the foundation. This is especially bad if there is a whole lot of water involved. For example, if a home's gutters are clogged and overflowing, more water will saturate the ground. That will cause greater pressure and increase the risk that water will be forced through cracks and pores in the foundation wall and into the basement.

Ideally, the dampproofing installed on the foundation exterior during construction will prevent this, but don't count on it.

Water in basements isn't the only worry.

Saturated backfill may cause clay soils around the house to soak up water and swell, pushing inward on the foundation. This can buckle a foundation wall, requiring a costly repair to stabilize it.

Or water collecting around the base of the foundation may wash soil from under the footings, undermining them and causing potentially serious foundation settlement.

The risk of poor runoff actually causing these problems is very site-specific and may not exist at your home. For example, some houses are on sites with soils so well drained that water buildup around the foundation is virtually nonexistent.

Expansive clay soils don't exist everywhere. Some foundations are strong enough to resist the forces exerted by expansive soils.

But why risk it? We're just talking about adding some dirt.

Inspector's Eye

Dean Uhler has been a home inspector for more than 12 years and is president of Baltimore-based Boswell Building Surveys, Inc. Uhler is a member of the American Society of Home Inspectors (ASHI) and is the treasurer of the Greater Baltimore Chapter of ASHI.

Questions, with name, address and daytime telephone number, about homes and home inspections can be faxed to 410-783-2517, e-mailed to real.estate@baltsun or mailed to Inspector's Eye, Second Floor, 501 N. Calvert St., Baltimore, Md. 21278-0001.

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