How to Get Rid of a Musty Smell in the Basement (for Good)
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A musty basement smell isn’t a cleaning problem. It’s a moisture problem. Air fresheners just make it smell like a damp basement with a pine tree in it.
Get rid of the moisture and the smell goes with it. Here’s how to find where it’s coming from and fix it for good.
Quick Picks at a Glance
| Product | Best For | Deal |
|---|---|---|
| Basement Dehumidifier (50-Pint) | Drying the air | Check Price on Amazon |
| Hygrometer | Measuring humidity | Check Price on Amazon |
| Concrete Crack Sealer | Small wall cracks | Check Price on Amazon |
| Downspout Extensions | Moving water away | Check Price on Amazon |
| Mold and Mildew Cleaner | Cleaning surface mold | Check Price on Amazon |
Step 1: Measure the Humidity
Get a cheap hygrometer. Basements should stay between 30 and 50% humidity. Over 60% and mold and mildew start growing, which is where that smell comes from.
Step 2: Find the Water
Check walls and floors for damp spots, white chalky residue (efflorescence), water stains, or condensation on cold pipes. Tape a square of plastic wrap to the wall for 48 hours. Moisture under the plastic means water’s coming through the wall. Moisture on top means humid air.
Step 3: Run a Dehumidifier
For most basements, this is the single biggest fix. Pick one sized for the space, set it to around 45 to 50%, and if you can, drain it to a floor drain so you don’t have to empty a bucket.
Step 4: Fix the Outside
Clean gutters, add downspout extensions so water lands several feet from the house, and make sure soil slopes away from the foundation. A lot of basement water starts on the roof.
Step 5: Seal Small Cracks
Hairline cracks in concrete walls can be sealed with a DIY crack sealer. Large, widening or horizontal cracks are structural warnings and need a foundation pro.
Step 6: Clean Any Mold
Small areas of surface mold on hard surfaces can be cleaned with a mold cleaner or detergent and water. Wear gloves and a mask. Porous stuff like old carpet, cardboard and drywall that stayed wet often needs to go. Large areas (more than about 10 square feet) are a job for a remediation pro.
Step 7: Improve Airflow
Move boxes off walls and floors, use plastic bins instead of cardboard, and keep air moving with a fan. Stagnant corners are where the smell lingers.
Keep Reading
Best Dehumidifiers for Basements and Bedrooms · Condensation on Inside of Windows? · Bathroom Fan Not Clearing Steam? · Best Smart Water Leak Detectors
FAQ
What causes a musty smell in a basement?
Excess moisture that lets mold and mildew grow.
What humidity should a basement be?
Between 30 and 50%. Over 60% invites mold.
Will a dehumidifier get rid of musty smell?
It removes the moisture causing it. Pair it with cleaning any existing mold and fixing water sources.
Is a musty basement smell dangerous?
Mold can affect people with allergies, asthma or sensitivities. Fix the moisture and clean mold promptly.
When should I call a professional?
For large mold areas, standing water, or foundation cracks that are wide, growing or horizontal.
