How to Get Rid of Musty Basement Smell
If you see visible mold growth (not just smell mustiness), see our mold removal guide before cleaning. Mold requires PPE and specific treatment methods.
What You'll Need
- 1
- 1
- Spray bottle
- Several boxes
- 1-2 bags
Step-by-Step Method
Place a hygrometer in the basement. Anything above 60% relative humidity supports mold and mildew growth. Target 30-50%.
Check for: condensation on pipes (insulate them), water seepage through foundation walls or floor, poor drainage around the foundation outside, dryer venting into the basement instead of outside.
Place a dehumidifier in the basement and set to 45-50% relative humidity. Run continuously. Empty the reservoir regularly or connect a drain hose to a floor drain.
Spray moldy or musty surfaces with undiluted white vinegar. Let sit 10 minutes. Wipe clean. For concrete floors, mop with vinegar-water solution.
Place open boxes of baking soda and bags of activated charcoal around the basement. Replace monthly.
- Do not seal basement walls without fixing the moisture source first (moisture gets trapped behind sealant and makes the problem worse)
- Do not use carpet in basements with humidity issues
- Do not store cardboard boxes on concrete floors (they absorb moisture and grow mold)
- Use plastic storage bins instead of cardboard boxes in basements.
- Ensure downspouts direct water at least 4-6 feet away from the foundation.
- Keep items off the floor on shelving or pallets to allow air circulation underneath.
Frequently Asked Questions
Excess humidity. Basements are underground, surrounded by moist soil, and often have poor air circulation. When relative humidity exceeds 60%, mildew and mold grow on any organic surface (wood, paper, fabric, drywall). A dehumidifier keeping humidity at 45-50% eliminates the problem at its source.
Sources & Methodology
Indoor humidity guidelines from ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers). Mold and mildew require relative humidity above 60% for active growth.
Last reviewed: March 20, 2026