Musty Basement or Closet Smell
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Quick answer: A musty smell means mold may be growing even if you can’t see it (CDC; EPA). Find and fix the moisture, clean what you can reach, dry the space, and keep humidity down with a dehumidifier. An air purifier won’t solve a mold problem (EPA).
⚠ Safety first:
- Wear an N-95 respirator, gloves and goggles without vent holes; for plain detergent and water, household rubber gloves are fine, but use natural rubber, neoprene, nitrile, polyurethane or PVC gloves with bleach or strong cleaners (EPA).
- Ventilate: open windows and doors, and run a fan that exhausts to the outdoors (EPA; CDC).
- Never mix bleach with ammonia or other cleaners; it makes a poisonous gas (CDC; EPA). If you use bleach, use no more than 1 cup of household laundry bleach in 1 gallon of water and follow the label (CDC).
- If you have asthma, allergies or other health concerns, talk to a health professional before cleaning, or have someone else do it (EPA).
Steps: easiest & free first
- Look and sniff for the sourceFREE · 15 min
Check walls behind furniture, under carpet edges, around pipes and below windows. EPA lists these as common hidden-mold spots. - Empty and air outFREE · 30 min
Pull items away from walls, open the closet or basement door, and move air with a fan. - Clean hard surfacesFREE
Scrub mold off hard surfaces with detergent and water, then dry completely (EPA). - Toss what can’t be savedFREE
Absorbent materials like carpet and cardboard may need to be thrown out if moldy (EPA). CDC says to remove carpets that were soaked and can’t be dried right away. - DehumidifySHOP
Run a dehumidifier and check with a hygrometer, aiming for 30–50% (EPA). - Fix outside waterFREE
Clean gutters and make sure the ground slopes away from the foundation (EPA). - Call a pro for hidden moldPRO
See below.
⚠ When to call a pro: the moldy area is larger than about 10 square feet (roughly a 3 ft by 3 ft patch) or there’s been a lot of water damage; you suspect mold inside walls, behind wallpaper or in the HVAC system (don’t run the HVAC if you suspect it’s contaminated); the water came from flooding, sewage or other contaminated water; or anyone in the home has health or breathing problems (EPA). Hire someone with mold cleanup experience and check references (EPA). EPA says to consider an experienced pro if you suspect hidden mold, since tearing out wallpaper or drywall can release lots of spores. Renting? See what you can fix vs. call your landlord.
Helpful supplies
| Item | Why | |
|---|---|---|
| Dehumidifier | Keeps basement humidity down | Check price [PLACEHOLDER – no affiliate link] |
| Hygrometer | Confirms you’re in the 30–50% range | Check price [PLACEHOLDER – no affiliate link] |
| Plastic storage bins | Keep stored items off the floor and away from damp | Check price [PLACEHOLDER – no affiliate link] |
Generic categories only; check the product label and your home’s needs before buying.