# Why Does My Apartment Smell Musty?

Source: https://smallspacepicks.com/blog/why-does-my-apartment-smell-musty
Published: 2026-09-13
Publisher: Small Space Picks

A musty smell is almost always moisture that has nowhere to go. Small apartments trap it easily: fewer windows, shared walls, closets packed against exterior walls and bathrooms without strong fans. The good news is that most causes are fixable without touching the building itself, and a few inexpensive habits stop the smell coming back.

## Find where the smell is strongest

Walk the apartment with the windows closed after it has been shut up for a few hours, and notice where the smell is strongest. Closets on exterior walls, under-sink cabinets, the bathroom, behind furniture pushed against cold walls and the area around the washing machine are the usual suspects. A smell that follows you everywhere often points to overall high humidity rather than one spot.

A cheap digital hygrometer tells you more than your nose. Indoor relative humidity that sits above about 60 percent for long periods lets mould and mildew grow on fabrics, walls and grout. Place the hygrometer in the room that smells worst for a day and compare it with a room that smells fine.

## Common causes in apartments

Drying laundry indoors, long hot showers with a weak extractor fan and cooking without a lid all add litres of water to the air every day. In a small home that moisture condenses on the coldest surfaces, usually window frames, exterior walls and the backs of wardrobes, where it feeds mildew you cannot see.

Drains are the other classic source. A sink, shower or floor drain that is rarely used can dry out its water trap, letting sewer air into the room, and a slow drain with built-up gunk smells sour. Leaks under the sink, a dripping washing machine hose or a damp patch from the apartment above also create persistent smells and should be reported to your landlord quickly.

## Fixes that do not risk your deposit

Lower the humidity first. Run the bathroom fan for 20 minutes after showering, crack a window while cooking, and dry laundry near an open window or with a dehumidifier running. A compact dehumidifier in the worst room often brings humidity down to 40-50 percent within days, which is the range where mildew struggles.

Give air a path. Pull furniture a few centimetres away from exterior walls, leave closet doors open for part of the day, and avoid packing clothes tightly. Moisture absorbers in closets and under sinks help in spaces where a dehumidifier will not fit. Run water in unused drains weekly to keep their traps full.

## Cleaning away the smell for good

Once the moisture is under control, clean the source. Wipe mildew from hard surfaces with a household cleaner suitable for the material, wash musty fabrics hot if the care label allows, and let everything dry completely before putting it back. Fragrance sprays only cover the problem and fade within hours.

Tell your landlord in writing about leaks, water stains, persistent mould or a broken extractor fan. These are building issues, and documenting them protects your deposit if damage is discovered later.

## When a musty smell means something bigger

A smell that returns within days of cleaning, visible black spots that spread, bubbling paint or a soft patch in drywall point to moisture inside the wall or floor, which a renter cannot fix alone. Photograph the area with dates and send the pictures with your written maintenance request.

If anyone in the home has asthma or allergies that worsen in a particular room, mention it to your landlord and doctor. Persistent damp is a habitability issue in many places, and building owners are usually responsible for leaks and structural moisture.

## Related buying guides

- https://smallspacepicks.com/best/small-dehumidifiers-for-apartments
- https://smallspacepicks.com/best/air-purifiers-for-small-apartments
- https://smallspacepicks.com/best/closet-organizers-for-renters