How to Get Rid of a Musty Smell in Your House (Fix the Cause, Not the Scent)

To get rid of a musty smell in your house, find and fix the moisture causing it, then dry the area and keep indoor humidity below 60 percent, ideally between 30 and 50 percent, as the EPA recommends. Wash or air out fabrics that hold the odor, clean small areas of mildew on hard surfaces with detergent and water, and ventilate. Sprays and candles only hide the smell while the cause keeps growing.

That damp, earthy “old basement” smell usually comes from mold and mildew growing somewhere moist. You may not see it yet. The smell is a clue to where to look.

What you need

• An inexpensive humidity meter (hygrometer)
• A flashlight
• Laundry detergent and dish soap
• Microfiber cloths and a scrub brush
• Fans, and a dehumidifier if humidity stays high
• Gloves, and an N-95 respirator and goggles if you’ll be cleaning visible mold, as the EPA suggests

Step 1: Find the moisture source

Walk through the house and follow your nose. Check these common spots:

• Under sinks in the kitchen, bathroom and laundry: look for drips, swollen cabinet floors or stains.
• Around toilets, tubs and showers: failing caulk and grout let water behind tiles.
• Basements and crawl spaces: damp walls, condensation on cold pipes, water after rain.
• Windows: condensation running onto sills and frames in cold weather.
• Closets on exterior walls: cold walls plus little airflow.
• The washer, dishwasher and fridge drip pan.
• HVAC system: clogged condensate drain lines or a damp air handler.
• Carpets that once got wet and didn’t dry completely.

Fix leaks first. The EPA’s mold guidance is clear that cleaning without fixing the water problem means the mold will come back (EPA: A Brief Guide to Mold, Moisture and Your Home).

Step 2: Measure and lower humidity

A hygrometer shows whether the air itself is the problem. The EPA recommends keeping indoor relative humidity below 60 percent, ideally 30 to 50 percent.

Ways to bring humidity down:

• Run bathroom and kitchen exhaust fans during and after showers and cooking. Make sure they vent outdoors.
• Vent the clothes dryer outside, and avoid drying lots of laundry indoors without ventilation.
• Use a dehumidifier in basements and other damp rooms. Empty or drain it regularly and clean it per the manual. See does a dehumidifier help with mold for sizing.
• Use air conditioning in humid weather.
• Open windows when it’s drier outside than inside.

If windows fog up from the inside in winter, read our guide to condensation on windows.

Step 3: Dry and clean

The EPA advises drying water-damaged areas and items within 24 to 48 hours to prevent mold growth. Once the area is dry:

1. Hard surfaces: scrub visible mold or mildew with detergent and water, then dry completely. That’s the EPA’s basic method.
2. Porous materials like ceiling tiles, drywall, insulation and carpet padding that are moldy may need to be removed and replaced.
3. Small areas only. The EPA says a moldy area under about 10 square feet can usually be cleaned yourself. For larger areas, mold in the HVAC system, or after sewage or flood water, get professional help.
4. Don’t paint or caulk over mold. Clean and dry first.

The EPA does not recommend chlorine bleach as a routine part of mold cleanup. If you do use bleach on a non-porous surface, use it only as the label directs, with windows open, and never mix bleach with ammonia, vinegar or other cleaners. Detergent and water are enough for most surface mildew.

Step 4: Deal with fabrics and soft items

• Clothes, curtains and bedding: wash in the warmest water the care label allows and dry completely. Sun-drying outdoors helps. Our guide to mold on clothes covers stubborn cases.
• Rugs and upholstery: vacuum, air them out on a dry day, and have them professionally cleaned if the smell lingers. Items that stayed wet for a long time may need to go.
• Books and paper: air them in a dry room with a fan. Badly moldy paper is hard to save.
• Cushions and mattresses that were soaked and smell moldy are generally not worth saving.

Closets and basements

In closets, leave a gap between clothes and the wall, keep the door open sometimes, and don’t store damp items. Plastic bins can trap moisture; make sure things are fully dry before packing them. In basements, keep gutters and downspouts directing water away from the foundation, insulate cold pipes, and run a dehumidifier during humid months.

Masking vs fixing

Safety notes

• Wear gloves and eye protection when cleaning mold, and consider an N-95 respirator for visible growth, as the EPA suggests.
• Ventilate while you clean, and follow every product label.
• Never combine cleaning products, and keep them out of reach of children and pets.
• If someone swallows, inhales or gets a cleaning product in the eyes, call Poison Control at 1-800-222-1222 (US) or emergency services.
• If anyone in the household has breathing symptoms or allergies that seem linked to the home, talk to a doctor.

Bottom line

A musty smell is a moisture problem. Track down the source, fix leaks, dry everything within a day or two, and keep humidity between 30 and 50 percent. Clean small mildew patches with detergent and water, wash fabrics, and call a professional for large areas. For a hidden source you can’t find, see how to get rid of mold smell.

FAQ

Does a musty smell always mean mold?

Usually it means mold or mildew growing on something damp, but stale air, a dry drain trap or wet fabrics can smell similar. Moisture is the common thread.

Should I test my house for mold?

The EPA generally doesn’t recommend sampling to identify mold types; if you can see or smell it, the advice is to fix the moisture and clean it up.

Will an air purifier fix a musty smell?

It may reduce some airborne particles, but it won’t stop growth on damp surfaces. Fix the moisture first.

Why does my house smell musty only in summer?

Humid outdoor air raises indoor humidity, especially in basements. A dehumidifier or air conditioning usually helps.