Prep first
Before you start
- Find the source first: look for leaks, missing exhaust fans, an unvented dryer and crowded closets.
- Smell for mold where you can't see it, since hidden mold can sit behind cabinets, wallpaper and under carpet.
- Gather your gear and the supplies listed below before you start.
- Don't run the central air if you suspect mold in the system, since it can spread mold through the building.
A musty smell in a house is a moisture problem first, and mold grows wherever that moisture stays. Mold can hide behind cabinets, behind wallpaper or under carpet, so the smell is often stronger than the mold you can see. Before you clean anything, find the water, because mold never grows without moisture.
Getting rid of a musty or mildew smell in the whole house starts with the water, not with air freshener. Scrub the mold off hard surfaces with mild detergent and water, then dry everything within 24 to 48 hours. Keep humidity between 30 and 50 percent so the mold has less reason to come back.
8 items
What you'll need
Tap an item to get it on Amazon, or tick what you already have.
- N-95 or higher respiratorProtects your lungs while you clean, and it should be fitted to your face. (opens Amazon)
- Long glovesKeep the mold and detergent off your hands while you scrub. (opens Amazon)
- Goggles without vent holesProtect your eyes during the scrub. (opens Amazon)
- Mild non-phosphate detergentCleans mold off hard surfaces when mixed with water.
- Damp clothsWipe the mold away, then use a clean damp cloth for the rinse.
- DehumidifierDries the air to between 30 and 50 percent humidity once the moisture source is fixed. (opens Amazon)
- Box fansRun one in an open window blowing outdoors, and use others to dry wet materials. (opens Amazon)
- HygrometerAn inexpensive humidity meter shows where the humidity really sits.
As an Amazon Associate we earn from qualifying purchases.
7 steps
Step by step
Step 1 of 7
Find the moisture and hidden mold
Mold never grows without moisture, so start by finding and fixing the leak, missing exhaust fan, unvented dryer or other water source. If the room smells musty but you see no mold, check behind cabinets and wallpaper and under the carpet.
Tip. Condensation on windows, walls or pipes is a sign of high humidity.
Step 2 of 7
Gear up and open the room
Put on your long gloves, goggles and respirator before you touch anything. Turn off central air and heating to reduce the spread of spores, then open windows and set a fan in one window blowing outdoors.
Careful. Goggles must have no vent holes, and the respirator must be an N-95 or higher that fits you.
Step 3 of 7
Throw out moldy porous materials
Remove absorbent or porous materials that have gone moldy, such as ceiling tiles and carpet. Bag them as you go so they don't spread through the rest of the room.
Careful. Removing wallpaper over mold can release a lot of spores, so consider an experienced professional for that job.
Step 4 of 7
Scrub the mold off hard surfaces
Wipe the mold off hard surfaces with a damp cloth and a solution of water and mild non-phosphate detergent. Work in small sections and keep wiping until the visible mold is gone, then let the area dry.
Step 5 of 7
Wipe again to pick up the detergent
Go over each cleaned section with a clean damp cloth so no detergent is left behind. Rinse the cloth often, since a dirty cloth just moves the mold around.
Step 6 of 7
Dry everything within 48 hours
Aim to dry the room within 24 hours, and never wait longer than 48. Run dehumidifiers and fans until the humidity sits between 30 and 50 percent, since mold can start on damp surfaces in about 2 days.
Step 7 of 7
Recheck the room for a few days
Look and sniff at the cleaned areas regularly over the next few days. If mold reappears within that window, the moisture problem is still there, so go back to finding the source.
What makes the job easier
Products that help
A hygrometer is the most useful product here, because it shows whether the room sits between 30 and 50 percent. Pair it with a dehumidifier sized for the space.
OdoBan Odor Eliminator & Disinfectant Concentrate
MOLD ARMOR Rapid Clean Remediation
How we picked these: each product is made for this kind of odor or surface, its maker doesn't warn against using it on musty house smell, and its directions fit the steps above.
Finished? How does it look?
Nice work. Let it dry completely before you use it again.
How to tell it's really done →A faint smell often fades as everything dries and airs out; give it a day before a second round.
Find the guide for your stain →Heavy grime or a lingering smell usually needs a second round once it's fully dry.
See what to do for what you're seeing →When to call a professional →How to tell it's done
A clean room has no visible mold, no musty smell, and surfaces that feel dry to the touch. Check that the humidity sits between 30 and 50 percent, and if the smell lingers after the room is dry, go back and look for the water or hidden mold.
If there is a stain too
Related guides
A smell usually has a stain or a spill behind it. These guides cover the cleanup in detail:
What changes for yours
Adjust for the room
Bathroom
Showers keep a bathroom damp, so moisture control matters most in this room. Run the exhaust fan during and after every shower, or open a window if you don't have a fan.
If mold keeps reappearing, clean more often and make sure the bathroom fan vents outdoors.
Basement
Basements are mold-prone when water seeps through the concrete and leaves them wet or damp, so check the walls and floor for moisture before anything else. Summer ventilation can push basement humidity up, so watch it closely in warm months.
Keep the humidity between 30 and 50 percent with a hygrometer, and run a dehumidifier if the reading stays high. Close doors and windows while it runs.
Closet
Closets get musty when clothing is stored damp or dirty, or when there is a cool outside wall. Remove at least one-third of the clutter so air can move through, then leave the door open or fit a louvered door.
Only store clean, dry clothing in here, since a crowded closet traps moisture.
Dryer and laundry area
Damp towels and unvented clothes drying cause mold in laundry areas. Make sure the dryer vent is connected and runs outside, and vent any other moisture-producing appliance outdoors too.
Brush, shake, sun and air mildewed clothes and towels outdoors first, then wash them at the hottest temperature the label allows. Repeat the wash until the mildew smell is gone, and dry them thoroughly.
Books
Stand the books on their ends and fan the pages so air can get through and dry them. Wipe off any mold with a clean dry cloth, then sprinkle talcum powder or cornstarch on the pages to absorb moisture.
Leave the powder on until the books are fully dry, then brush it off before you shelve them. Keep the room between 30 and 50 percent humidity so the books stay dry on the shelf.
Prevention
Keep the smell from coming back
Keep the humidity between 30 and 50 percent, and check it with an inexpensive hygrometer. Stop using a humidifier if the reading goes above 40 percent, and never let the humidity climb past 60 percent.
Dry any leak or spill within 24 hours, and never let it go past 48. Vent dryers, stoves and other moisture-producing appliances outdoors, and use an air conditioner or dehumidifier when the air is damp.
Make sure the ground slopes away from the foundation and keep gutters clean. Cover cold water pipes with insulation to stop condensation, and recheck cleaned areas regularly.
Vinegar, baking soda, peroxide and more
Do home remedies get rid of the smell?
The mold and the musty smell come from moisture, so no remedy in your cabinet replaces fixing the water. Mild detergent and water handle the cleanup, and most remedies in your cabinet add little to it.
Helps3Skip3Avoid1
What makes it worse
Mistakes to avoid
Don't skip fixing the water
Killing the mold is not enough, because the mold and its smell come back until the water problem is fixed. Cleanup is not finished until the moldy odor is gone and the moisture is under control.
Don't paint or caulk over mold
Covering mold hides it without stopping it from growing. Clean the area and let it dry before you paint or caulk.
Don't leave wet materials sitting
Materials that stay damp can grow mold quickly, so get them dry within 24 hours and never past 48. If something still isn't dry after 48 hours, throw it away.
Don't mix bleach with ammonia
Bleach mixed with cleaners that contain ammonia makes toxic fumes. Check the labels of every cleaner before you start, and keep the two apart.
Don't use bleach as the routine cleaner
Bleach isn't recommended for everyday mold cleanup, so skip it. Use the detergent and water in the steps, and check the room with your nose after each clean.
Troubleshooting
If the smell comes back
Pick what you're seeing:
The smell comes back within a few days
Mold can return in 2 to 3 days when moisture is still present, which means the water problem isn't fixed. Look again for the water source, and check behind cabinets, wallpaper and under carpet.
Water beads on windows, walls or pipes
That condensation is a sign of high humidity, so check the room with a hygrometer. Run a dehumidifier with doors and windows closed until the reading sits between 30 and 50 percent.
When to call a professional
Mold covering more than about 10 square feet, or a lot of water damage, calls for professional-level remediation guidance. Sewage or other contaminated water damage needs an experienced professional, and any contractor you hire should have mold experience. If mold keeps coming back, remove the material and consider a water damage or mold restoration firm.
Questions
What does mildew smell like?
Mildew and mold smell musty or earthy, and that smell is one of the common signs of mold. If you can smell it, you have a problem to find, even when you can't see any mold yet.
What causes a musty house smell?
Common moisture sources include crawl-space water, poor drainage, many indoor plants, a large aquarium and an unvented heater. Any of these can keep the air and surfaces damp enough for mold to grow.
Does a dehumidifier get rid of the smell?
A dehumidifier helps by pulling moisture out of the air, but it won't fix a leak or clean existing mold. Match its capacity to how damp the room is, and go larger rather than smaller. Keep doors and windows closed while it runs, and switch it off to defrost if the room drops below 65 F, since frost forms on the coils.
What if the mildew smell is only in the bedroom?
Work through the same cleanup in that room: look for a leak or damp wall, and check behind cabinets, wallpaper and under the carpet for hidden mold. Then move furniture away from the walls and open closet doors so the air can circulate.
Do I need to kill the mold with a disinfectant?
Dead mold can still cause allergic reactions, so it has to be removed, not just killed. If you do use a disinfectant, ventilate the room and exhaust the air outdoors.
Do I need to test the air for mold?
Testing is generally not necessary, since your eyes and nose usually tell you whether mold is still there. Keep checking the room by sight and smell for a while after cleaning, because a smell that returns means the moisture problem is still there.
Start from the bigger picture
More odor guides
How we know this
Every method, amount and warning here comes from university extension services, industry bodies and product makers. We read them, check every step for unsafe combinations and changed amounts, and write it up so you can follow it.