Interior Basements

Solved! What’s Up with the Musty Smell in My Basement?

Understand where that nasty odor is coming from and banish it for good with this four-part plan.
Musty Smell in the Basement? 4 Steps to Freshness


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Q: Lately, I notice a musty smell whenever I go into my basement. What’s causing the odor and most how do I get rid of it?

A: That unpleasant, musty smell—some people describe it as akin to a wet dog—in is the calling card of mold and/or mildew. The spores of these ubiquitous fungi drift through the air until they find the damp, dark, and warm environment that allow them to multiply and thrive—conditions common to basements.

Although the majority of mold species found inside homes aren’t harmful to humans, some people are allergic to the spores and develop symptoms that include a stuffy or runny nose, headache, fatigue, coughing or wheezing, and itchy or runny eyes after spending time in a mildewed or moldy room. Stachybotrys chartarum, commonly called black mold, is linked to more serious symptoms, including chest tightness and difficulty breathing, a burning sensation in the nose and throat, dizziness, headache, and trouble concentrating. Luckily, however, black mold isn’t nearly as common as less toxic types.

The musty smell in your basement from unfettered mold and mildew growth also presents potential harm to your home’s structure.

These fungi feed on organic materials, which include wood, many types of fabric, paper, and even some glues. Given enough time, mold can heavily stain your walls, floors, and ceilings; decay wood studs and drywall; damage carpets; and eat away at wallpaper. Mold that’s reached this level requires the services of a professional trained in mold remediation, but you can easily deal with a simple case of funky mildew smell and mild mold staining yourself.

RELATED: 12 Big Mistakes That Lead to Mold and Mildew Growth

Simply banishing the odor won’t eliminate the issue, though; mold and mildew spores can start to multiply in as little as 24 hours if conditions are perfect, so to really conquer the stink, you must tackle the problem at the root by following these next four steps.

Here's What Causing That Musty Smell in the Basement

Look for leaks in the basement that might lead to mold and mildew growth.

Discovering the source of humidity in your basement is the key to vanquishing mold and mildew (and may alert you to other issues as well). Two common and easily handled problems are condensation dripping off an uninsulated pipe or water leaking through a basement window.

  • Many basements have exposed pipes running along the ceiling or down the walls. If you spot water “sweating” off these pipes, insulate them with foam pipe wrap, available at home improvement center for less than $10. The lengths of rubbery foam are pre-cut so you can easily slip them right over pipes. However, if the pipe is actively leaking, not just sweating, call a plumber without delay to repair it.
  • If your basement has windows, look for water running down the glass or puddling underneath the window when it rains. If you spot water, remove leaves and other debris that could be clogging the outside window wells. Fill the wells with gravel to help reduce the chance of clogs. Replace old weather stripping and caulk, as well, to seal any small leaks around the window frames.

If you see water coming through a crack in the basement wall or seeping up from the foundation, the problem is a serious one outside the scope of the typical homeowner’s DIY abilities. Contact a contractor who specializes in basement repairs and waterproofing.

Lower the humidity level to under 60 percent with a dehumidifier.

Due to its underground position, your basement tends to stay cooler than the upper levels of your home during the warmer months. That can be a problem, though, when warmer air from upstairs circulates into the basement. As the warmer air rapidly cools in the basement’s lower temperature, water vapor condenses into a film of moisture that settles on the basement walls, as well as any furnishings or other items stored in the space. Moisture from the soil can also seep into a basement through the foundation, increasing indoor humidity further.

The preferred level of indoor humidity for most people is between 30 and 50 percent, while mold thrives with humidity of 60 percent or higher. Test your basement’s level with a hygrometer (available at Amazon), which shows the relative humidity of a room at a glance. Then, consider purchasing a dehumidifier to make things more comfortable for you, and less hospitable to mold and mildew.

Among the several types of dehumidifiers available, a compressor dehumidifier is best suited to basements. These devices reduce air humidity by sucking the room air over chilled coils, causing the moisture to condense into a storage tank. A good choice an average-size basement is the Frigidaire 70-Pint Dehumidifier with Effortless Humidity Control (available at Amazon).

RELATED: The Best Dehumidifiers for Any Basement

Musty Smell in Basement? Here's How to Clean Up

Clean up all mold or mildew spores present.

Once you’ve gotten excess humidity under control, clean away the odor-producing mold and mildew.

  • Start by getting rid of any moldy or soggy cardboard boxes or other papers you’ve been storing in the basement. Mold thrives on paper products. Pack away salvageable holiday decorations and other items in large plastic containers with securely fitted lids.
  • Wash and dry any garments on the hottest settings safe for the fabric to remove mildew and mold spores.
  • Trash seriously stinky upholstered furniture, but try to save a lightly affected piece with spot treatment. First vacuum the piece (discarding the filter and bag when you’re done), then wipe it down thoroughly with a clean sponge dipped in a mixture of equal parts water and rubbing alcohol. Let it air dry completely outdoors in a sunny spot for several hours—UV rays of direct sunlight kill mold spores.
  • Next, tackle any spots of mold on the walls, ceiling, or floors with bleach. Mix four parts of water to one part of household bleach and take a stiff cleaning brush to the surface. Once the mold spots are gone, wipe the surfaces with clean water on a clean sponge and then let air-dry.

Neutralize the musty smell in the basement.

To remove any lingering musty smell, try the old-fashioned yet effective remedy of setting out a few small bowls of baking soda around the room; baking soda absorbs and neutralizes odor molecules well. Alternately, set out a few bowls of white vinegar, which also neutralize odor molecules. For more resistant smells, it’s hard to beat the moisture-and-odor-absorbing qualities of DampRid, which contains salt crystals. A four-pound tub, large enough for up to 1,000 square feet, should cost you less than $10 at Amazon.