How do I keep my house from smelling musty?

Control moisture and the smell stays away

A musty smell is the smell of damp. The key to mold control is moisture control.^[1] So keeping a house from smelling musty means keeping water out, and drying quickly what gets in. Air fresheners, candles and baking soda cover the smell without touching the cause.

If the smell is already there, start with how to get rid of a musty smell in your house, then use this page to keep it from returning.

Hold humidity in the right range

The target is simple. If possible, keep indoor humidity below 60 percent (ideally between 30 and 50 percent) relative humidity.^[1] A small humidity meter lets you see the number instead of guessing, so put one in the basement, the bathroom and any closet that smells. Basements and rooms with little air movement are where the meter matters most.

When the number runs high, use an air conditioner or dehumidifier when needed, along with ventilation.^[1] Run the bathroom fan or open a window when showering, and use exhaust fans or open windows whenever cooking, running the dishwasher or dishwashing.^[1]

Vent and drain water away from the house

Much of the moisture in a house comes from outside or from appliances. The EPA's prevention list covers the main ones:

• Vent appliances that produce moisture, such as clothes dryers, stoves, and kerosene heaters to the outside where possible.^[1]
• Clean and repair roof gutters regularly.^[1]
• Make sure the ground slopes away from the building foundation, so that water does not enter or collect around the foundation.^[1]
• Keep air conditioning drip pans clean and the drain lines unobstructed and flowing properly.^[1]

Stop condensation and dry things quickly

If you see condensation or moisture collecting on windows, walls or pipes, act quickly to dry the surface and reduce the moisture source. Condensation can be a sign of high humidity.^[1] Cover cold surfaces, such as cold water pipes, with insulation.^[1]

Speed matters after a leak, a spill or a wet towel. If wet or damp materials or areas are dried 24-48 hours after a leak or spill happens, in most cases mold will not grow.^[1] Wet carpet, a soaked box in the basement and a damp towel on the floor all count. Dry them, move them or throw them out.

Small habits that help

• Leave a gap between furniture and outside walls so air can move.
• Keep closet doors open now and then and do not pack closets tight.
• Wash and fully dry bath mats, towels and shower curtains.
• Replace the furnace and air conditioner filter as the manufacturer directs.
• Do a monthly sniff-check of the trouble spots: under sinks, the basement, the laundry corner and the garage wall.

Stop and call a pro if

• The smell keeps coming back after you dried and cleaned. The water source is still there, probably out of sight in a wall, a floor or a crawl space.
• Humidity stays high even with a dehumidifier running. That points to a leak, groundwater or a ventilation problem. See how to keep a crawl space dry and how to prevent mold in a basement.
• The smell is strongest at the vents. EPA says a suspected mold-contaminated HVAC system calls for caution before you take further action, so have it checked rather than running it to clear the air.^[2]
• You find a stain that grows or a patch of mold bigger than about 10 square feet. The EPA says you can usually handle less than that yourself.^[2] Beyond it, EPA points to its remediation guide, and a remediation company is the usual route. Read what professional mold remediation involves.
• A leak soaked drywall, carpet or insulation. Materials that stayed wet may need to be removed, and a restoration company can dry and treat them.

Getting help in Virginia

For prices and when it makes sense to hire, see how much odor removal costs in Virginia and when to hire an odor removal company. More guides are in restoration answers and the restoration directory.

If the musty smell is stubborn or you cannot find where it starts, describe the problem once and local pros can quote it.