The American Society of Home Inspectors has some pretty surprising statistics about wet basements:

• Most new homes will develop a leak somewhere in the basement within 10 to 15 years of being built.
• Over 60 percent of basements in existing homes have a moisture problem.
• Around 38 percent of basements with moisture problems develop mold and fungus growth.
• Older homes were built with waterproofing methods that are now outdated and no longer work.

Finding the source of the moisture is the first step toward solving the problem, but it’s a lot easier said than done.

Causes of a Wet Basement

The most common culprits of a wet basement are groundwater, rain and melting snow accumulating around the home’s foundation. From there it will seep through cracks and around joints.

Condensation is another cause of a moist basement. You’re probably familiar with condensation as the water droplets that appear when the outside cooler temperatures meet the warm glass of a window in a heated room.

This same principle applies when moist, warm air hits the cold concrete foundation or cold water pipes. The condensation can puddle, drip and accumulate.

Finding the Leak

John D. Wagner, of This Old House, offers an innovative and easy way to tell if the moisture in the basement is being caused by condensation or if it is intruding from outside. Tape a piece of foil to a wall where you’ve found moisture. Leave it affixed to the surface for a day. If the outer surface of the foil is damp, suspect condensation. If the underside of the foil is wet, water is most likely intruding from the outside.

If the cause of the moisture still isn’t apparent, do some sleuthing. Look for water damage at the area of the floor where it intersects with the wall, and in the ceiling. Any discoloration or flaking of paint is evidence of moisture intrusion.

The most common evidence of a leak in your basement is the odor or appearance of mold. If you can’t see mold, but the air smells musty or earthy, there is mold present somewhere. Find it and you’ll find the source of the leak.

Check for evidence of scaling – salty looking deposits on stone, stucco and concrete surfaces.

Other evidence of a water leak in the basement include:

• Rotting wood.
• Buckled floors.
• Rusty nails or screws.
• Rusted metal on the feet of appliances.
• Lifting tile floors.

Fixing the Problem

Fixing a wet basement may be a simple task, such as airing out the basement to rid it of condensation. Or, it may be a costly and time-consuming procedure. Depending on the cause of the leak, rectifying the wet basement situation may entail:

• Redirecting surface water in the yard by re-grading the soil or installing drains.
• Cleaning or replacing the gutters and downspouts.
• Filling cracks with epoxy.
• Installing dehumidifiers, flashing and additional downspouts.
• Installing a sump pump.

Dampness in the basement can cause a lot of damage to the home’s structure and integrity, and, if mold develops, the air could become unhealthy to breathe. If you can’t find or repair the leak on your own, call a professional.