Problem:

Your basement is damp, which can lead to mold and mildew growth, rotting, structural damage, peeling paint, and a number of health problems.

Dampness in your basement comes from either a water leak or high humidity. Each can have a variety of causes. Water can leak in from the outside, through cracks in the foundation or gaps around windows and doors - or it can come from inside the house, from a leaking pipe, toilet, tub or shower. Or the dampness may result from high indoor humidity, which also has a variety of causes. Everyday activities like cooking, showering and drying clothes all increase indoor humidity. Moisture may be migrating through the concrete foundation and evaporating. Or condensation may be forming on the cold concrete walls and floors during the hot months. These are all common problems that could lead to dampness in the basement.

Recommendations:

• The first step is to find evidence of the problem, which can lead to the cause. Is there standing water on the floor? Is there water damage on the ceiling or the wall, which could point to a water leak? Does the problem occur in a large area, like an entire wall or a whole room? Then it may be caused by excess humidity. See the sections below for help on stopping leaks and reducing humidity.
• If you think there may be mold growth in your home, read the EPA's Brief Guide to Mold in Your Home. Call a mold remediation contractor to remove the mold, which can cause health issues.
• Correct any moisture issues before remodeling your basement. Use the tips below and consult the EPA's guidelines for controlling moisture.

Stop Water Leaks

• If there are water stains on the ceiling or wall, you may have an indoor leak. Call a plumber to investigate and repair the leak.
• If there's standing water on the basement floor after a heavy rainfall, your problem likely comes from a leak in the foundation. Try these remedies:
  • Clean out the rain gutters and make sure the downspouts lead at least 3 feet away from the foundation.
  • Check the ground next to the foundation to see if it slopes away from the house. If it doesn't, you will need to re-grade the ground so it slopes down, away from the foundation.
  • Check your sump pump (if you have one) to make sure it's working properly.

Reduce Indoor Humidity

• Use ventilation fans when cooking and during baths or showers and for 15 minutes afterwards. Make sure that the fans are exhausting the air to the outside, and not into the attic. Check the ductwork to ensure that it's not blocked or disconnected.
• Use a dehumidifier in the basement during hot humid months to reduce condensation on the walls. For best results, seal air leaks in the building and the ducts. This will reduce the amount of humid outdoor air that enters the basement.
• Seal air leaks in the building shell and seal air ducts to reduce humidity levels in your home.
• Your clothes dryer is a large source of humidity. Make sure it's vented directly to the outside. Inspect the vent duct to ensure that it's clear of obstructions such as lint, and that it's attached securely to the dryer. If the vent duct is damaged or has holes that leak air, replace it with a metal duct. For your safety, clean the vent duct at least once a year. Use these safety tips for dryer vents from The Consumer Products Safety Commission.
• Have an HVAC contractor inspect your heating and cooling system to make sure it's operating correctly and properly sized to remove the humidity from your home. Have them check your ductwork for proper sizing, air leaks and to see if enough air is flowing to each room.
• If you have a dirt floor in your basement, cover it with a plastic sheet to reduce the amount of water vapor that evaporates up through the floor.

Home Energy Problems & Solutions:

• Reduce High Energy Bills Energy Efficiency, Home Improvement Tools
• Drafty Rooms Air sealing, Heating and Cooling Contractor
• Peeling Paint Control moisture, Building Science Specialist
• Mold, Mildew or Musty Odors Reducing Indoor Humidity
• Dust Sealing air leaks, Change Filters
• Hot or Cold Rooms Room over a garage, ENERGY STAR ceiling fans
• Damp Basement Stop water leaks, Ventilation Fans
• Moisture on Windows Control Moisture, ENERGY STAR Labeled Windows
• Dry Indoor Air in Winter Home Sealing, Diagnostic Equipment
• Cold Floors in Winter Basement floor, Floor over a crawlspace
• Ice Dams Roofing Contractor, Diagnostic Equipment