Proper Basement Drainage

Basements often flood when the ground is improperly graded.

Homes with inadequate drainage systems often develop moisture problems in the basement. Damp, wet basements are prime for mold growth and structural damage often occurs when moisture is present for extended periods of time. Most problems with basement drainage can be solved by taking a moment to look around your home for problem areas. Once you have identified the cause of excess moisture, you can take steps to install proper basement drainage systems or remedy the cause of moisture seeping into your basement from outside areas.

Causes

The foundation of your home can be damaged by surface water that runs into your basement or by water leaking in from the roof. Your basement may be especially damp if a dirt floor is in place instead of concrete, which causes high humidity when water evaporates through the soil and moves through your home. Leaking roofs and improperly graded soil are also common causes of poor basement drainage. Inspecting your home on a regular basis for drainage problems can help you diagnose the cause of poor basement drainage.

Effects Of Moisture

If your basement does not have adequate drainage in place, excess moisture can cause a myriad of problems. When your basement is damp from leaking water, the humidity level is higher than the recommended level of 30 to 50 percent, which causes your home to feel uncomfortably damp. Standing water or water leaks for prolonged periods may eventually cause mold growth. When mold begins to grow, it breaks down the structure it is growing on such as drywall or wood. This can result in repairs that may be costly. Mold growth is a health hazard for those living inside your home. Even though most basements are unoccupied spaces, mold spores can become airborne and cause serious health effects such as wheezing or difficulty breathing.

Diagnosis

To be sure your home has proper basement drainage, go outdoors and inspect the ground around your home. The ground must be sloped away from your home, so that water from rain and snow run away from your home's foundation. Poor final grading of your lot is a common cause of excess basement moisture. Your gutters and downspouts may become filled with leaf litter and debris, causing water to run inside your home. If your home does not have drain tile beside the footing, water may run into your basement, as well. Sump pumps are designed to pump excess water out of the basement when water levels are high. Homes without a sump pump often have problems with flooding, especially during the rainy season when moisture is abundant.

Solution

Since improper grading causes poor basement drainage, it may be necessary to have your lot regraded to direct water away from your home. Clean all gutters and downspouts removing leaf litter so water does not back up into your home. If your downspouts drain water close to your home's foundation, purchase downspout extensions that will carry water farther from your home. Placing 6 inches of gravel over your dirt floor basement will help keep water vapor from causing moisture problems in your basement. Install a sheet of plastic over the gravel as a vapor barrier. For homes with serious basement drainage problems, the Environmental Protection Agency or EPA recommends installing either a drain pipe or sump pump to remove excess moisture from around the footer of your home. Be sure to place a cover on your sump pump to keep dangerous gases and pollutants from entering your home.

References

• EPA: Moisture Control: 1.1 Site And Foundation Drainage
• NDSU: Keep Your Home Healthy; Kenneth Hellevang; 2004