The Dangers of Damp—Identify Sources of Moisture in Your Basement or Crawl Space, and Learn How to Fix Them


Water is the enemy of your home. But it’s not just full-on flood, standing-water-in-your-basement water that homeowners need to worry about. Moisture and dampness can be just as damaging if left unchecked, and can result in health-damaging mold and mildew or structural issues.

Because they are underground and tend to be dark, basements and crawl spaces are the top problem-areas for moisture in most homes. How do you know if you have an issue? Look for these signs:

  • Musty, unpleasant odors

  • Indoor air that feels damp or humid

  • Water stains, dampness, or seeping water around the base of the walls

  • Condensation on walls and floors

  • Efflorescence, a white or grayish powdery substance on unfinished basement walls

  • Wood rot: This is the most serious issue. Check for two types, and if you spy either contact a professional:

    • Wet rot: Look for discoloration, and a soft, spongy feel; you may also see fungus growth

    • Dry rot: Examine exposed wood for a white film, called mycelium

If you notice any of these red flags, start checking for the source of moisture. Cracks in the foundation, gaps around doors or windows, and leaking pipes are all prime culprits. Once you’ve found the source, try these simple, low-cost, do-it-yourself fixes:

Regulate Indoor Humidity: Too much moisture in the air can cause or exacerbate moisture problems. The fix could be as easy as investing in a dehumidifier; make sure that the unit you buy is the right size for your space, and either run a line to a drain to dispose of water or empty the collection bin regularly to make sure the unit can keep removing water from the air. Check that clothes dryers and ventilation fans are vented directly outside and are free of obstructions. Avoid hanging clothes to dry, which will just increase the humidity, and keep windows and doors closed when it’s humid outside.

Inspect the Foundation: Cracks—even small ones—in the foundation can allow moisture and water to seep into your home. You can seal small cracks that don’t affect the structural integrity of your home on your own. Save on expensive caulk by first filling cracks with Mortite Caulking Cord and then filling the crack with a caulk made for use with concrete.  If cracks are wider than ½”, it’s time to call in a professional to do a thorough inspection.

Check Grading. Soil along the foundation should slope away from the foundation wall a minimum of 1 inch per foot for 4 to 6 feet. If the soil around your foundation is level or slopes towards the house, water can collect along the basement wall and cause moisture or water issues. If you water your lawn regularly, take care to turn sprinkles away from your home to avoid directing any additional water towards your home.

Do a Gutter Check. Check for missing gutters and downspouts, which can direct rainwater towards your home’s foundation. Make sure all downspouts are connected and are long enough to direct water away from your house. Next, look up: there should be one downspout per 50 linear feet of roof.  

Seal Windows and Doors: Water and moisture can make its way into your home through small gaps around windows and exterior doors. Check basement windows to see if the seal around the window has deteriorated. To replace, remove damaged caulk and weatherstripping with a putty knife and wipe the window and frame with a damp cloth to get rid of any remaining gunk; apply caulk around all exterior molding. Inside, apply Frost King Poly Foam Weatherseal around the edge of the window. This highly compressible self-stick tape squeezes down to fill even very narrow gaps to create a tight seal.

If you have exterior doors in your basement, check that the weatherstripping around the door is intact and replace if necessary. Moisture can also leak under the door, so you may need to install a door sweep, like Frost King’s Aluminum Drip Cap and Door Sweep, to keep out any wetness.

Insulate Cold Water Pipes: When warm air in your crawl space or basement meets exposed pipes that carry cold water, droplets of water can form and cause the pipes to sweat. Fortunately, there’s an easy, do-it-yourself solution to eliminate this problem: just insulate the pipes to stop the dripping. Frost King Rubber Pipe Insulation Tape and Mortite No Drip Tape stops condensation on cold water pipes permanently. Watch this video to learn how to pick the right insulation for your pipes.

If these measures don’t help, you may need to take more drastic action. Next steps can include installing a sump pump and drainage system to pump out water.  

Disclaimer: The information provided in this blog post is for educational and informational purposes only. Homeowners should always consider safety precautions before starting any home improvement project.  While we strive to offer accurate and helpful advice, Frost King does not assume responsibility for any actions taken based on the information provided or for any consequences resulting therefrom.