Basement Moisture

Summary: Moisture in the basement causes mold, mildew and wood rot and decreases the energy efficiency and comfort of your home.

All basement moisture problems are caused by poor or improper drainage of rain and runoff water outside the house.

It is impossible to have a dry basement without eliminating the source of moisture.

And if you want to create a comfortable basement living space you’ll need to insulate your basement for energy efficiency.

But moisture in basements can reduce some or all of the interior insulating materials R values.

So, whether you are building a new home or a home addition, or fixing an existing moisture problem on an existing house the secret to moisture control in basements is to fill in the low areas and grade the entire area so that water drains away from the house.

Slope the earth away from all sides of the house. Here are simple construction details in animation for a moisture-resistant basement from BuildaBetterHome.org

Note: Absolutely NO part of the upper area of the foundation wall should be below the surrounding grade.

Install gutters and make sure that the downspouts are diverting water far enough away from your house.

If necessary, construct drainage swales to direct rainwater around and away from the foundation.

Right Way

Wrong Way

Grading the earth is easier if you are building a new home.

If you are trying to fix a basement moisture problem on an existing home, there are no shortcuts. Dig out around the house and do it right.

For more information on moisture in basements here are two excellent sources:

1. Moisture Control in Basements

2. BuildaBetterHome.org

Carl Heldmann