Waterproofing Options for Concrete Foundations

Stopping water from infiltrating basement walls requires choosing the right waterproofing system and installing it properly By Bill Palmer and Paul Newman

Other than burning down, probably the worst thing that can happen to a residential structure is a foundation problem. The foundation is literally what the house is built on, what keeps the building where it was built, transferring the dead loads and the live loads into the ground.

The source of the vast majority of foundation problems is water. Wet soil beneath a foundation can swell or lose strength.

And that's only the first reason to keep the foundation dry. Then there's the little problem of wet damp basements and crawl spaces that can breed mold and make below-ground interior spaces generally unpleasant. The problem is that typical concrete is not waterproof. Although uncracked (and what concrete is uncracked?) it will typically keep out liquid water, water vapor can still penetrate quite easily. Keeping water drained away from concrete foundations and preventing it from moving through the concrete are essential to a successful structure.

Accomplishing our goal, then, of draining any water away and ensuring a dry interior space below grade can be relatively simple or fairly involved depending on geographic location, climate, topography, soil/water table conditions, and depth of the foundation. There are three components of any system designed to keep water out. These are, from the bottom up:

Drains to move water away from the bottom of the foundation

Wall treatment to prevent moisture from moving through the wall and to route water down to the drains

Ground surface treatment adjacent to the building to direct surface water away

And remember that since this will mostly be underground when the building is complete, doing it right the first time is critical, because coming back to fix it is an expensive undertaking. A leaky foundation in a residential building can damage finishes and furnishings, even the structure itself. In a commercial building, water can ruin expensive equipment and disrupt vital work. It all adds up to lost money, wasted time, upset customers and sometimes litigation.

Acknowledgment: Portions of this section were reprinted from the March 1995 issue of Journal of Light Construction by permission of the publisher, Builderburg Partners Ltd., Richmond, Vt.