How to get rid of a musty smell in a room

A musty smell in a room is almost always a moisture problem wearing the disguise of a smell problem. That stale, earthy, slightly damp odour comes from moisture sitting somewhere it should not: in fabrics, in walls, behind furniture, under a rug. To get rid of a musty smell in a room for good, find where the moisture is coming from, dry the room out, and keep the air moving. Candles, sprays and diffusers can make the room smell nicer for an hour. They cannot fix the cause.

Why rooms smell musty

The smell usually means moisture has lingered long enough for mildew or mould to start growing, often somewhere you cannot see. The most common reasons are ordinary:

• Condensation, especially in cold weather: warm, moist air from breathing, cooking, showers and drying laundry meets cold windows and walls and turns back into water.
• Poor ventilation: rooms kept closed, windows rarely opened, extractor fans not used or not working.
• Drying clothes indoors without opening a window, which releases a surprising amount of water into the air.
• Furniture against cold walls, especially outside walls, where air cannot circulate and condensation collects behind wardrobes, beds and sofas.
• Damp fabrics: rugs, curtains, upholstery and bedding that absorb moisture and never quite dry.
• Leaks and building damp: a slow plumbing leak, a damaged gutter, rising damp or water getting in through a wall, roof or window frame.

The first five are about how a room is used. The last is about the building, and no amount of airing will solve it.

Step 1: find the source

Before you clean anything, look.

• Check the windows in the morning. Water pooling on glass and sills means condensation is a daily event.
• Pull furniture away from the walls, especially outside walls, and look behind and underneath. Dark spots, a damp feel or a stronger smell point to the problem area.
• Look at corners, ceilings and the tops of walls, particularly near windows and in rooms above or next to bathrooms.
• Sniff the soft furnishings. Rugs, cushions, curtains and mattresses can hold the smell long after the cause has gone.
• Look for signs of a leak: staining, bubbling paint, peeling wallpaper, damp patches that grow after rain, or a meter that moves when nothing is running.

A cheap hygrometer, which measures indoor humidity, can help. Readings that stay high for long periods suggest the room needs more ventilation or drying.

Step 2: dry the room out

• Ventilate every day, even briefly in winter. Opening windows for ten or fifteen minutes, ideally on opposite sides of the home, swaps damp indoor air for drier outside air far faster than leaving a window slightly open all day.
• Use extractor fans while cooking and showering, and leave them on for a while afterwards.
• Keep doors closed on bathrooms and kitchens while they are steamy, so the moisture does not spread into other rooms.
• Dry laundry outside when you can, or in one room with the window open or a fan running.
• Wipe condensation off windows and sills each morning.
• Leave a gap between furniture and walls so air can circulate.
• Keep the room evenly and moderately warm if you can. Cold rooms collect condensation; rooms that are heated hard for a few hours and then left cold often suffer most.

A dehumidifier helps a great deal in a persistently damp room, but these habits matter whether you have one or not.

Step 3: deal with what holds the smell

Once the room is drying out, the smell will often linger in fabrics.

• Wash curtains, cushion covers, throws and bedding according to their care labels, and dry them thoroughly before putting them back.
• Air rugs and mattresses, outdoors on a dry day if possible.
• Vacuum thoroughly, including under furniture, behind radiators and along the edges of the floor.
• Clean hard surfaces with an ordinary household cleaner.
• Bicarbonate of soda (baking soda) sprinkled on carpets and upholstery and vacuumed off after a while can help absorb lingering odours. Bowls of it, or of charcoal, help a little in small enclosed spaces. They absorb odour, not damp.

What about mould?

If you find mould, the priority is the moisture that caused it, because mould returns quickly to the same damp spot. For a small patch on a hard surface, a cleaning product made for mould, used exactly as its instructions say, with the window open and gloves on, is the usual approach. Do not mix cleaning products, and do not try to scrub mould off porous materials such as plasterboard, wallpaper or fabric that may need replacing instead.

If mould covers a large area, keeps coming back, or appears with signs of a leak or structural damp, it needs proper investigation. Renters should report it to their landlord or managing agent in writing as early as possible; homeowners should consider a builder or damp specialist. What landlords are responsible for, and how quickly, depends on where you live, so check the rules in your area.

Why air fresheners don’t solve it

Scented candles, plug-ins and sprays add a smell on top of the musty one. They can make a room pleasant for an evening, and there is nothing wrong with enjoying them. But masking the smell does nothing about the damp producing it, and in a room that is already short of fresh air, layering on more fragrance usually just makes the air heavier. Fix the moisture first. Then the room will smell of nothing in particular, which is what a clean room should smell like.

Keeping it away

• Air the room every day, briefly and properly.
• Use extractor fans and keep steamy rooms’ doors shut.
• Keep furniture a few centimetres off outside walls.
• Dry laundry outside or with ventilation.
• Watch the windows: a lot of morning condensation is an early warning.
• Act on leaks and damp patches quickly.

The same principles apply in smaller spaces too. A wardrobe that smells stale is usually a room problem in miniature, and our guide to getting rid of a musty smell in a wardrobe covers it. Airing the bed each morning, as we suggest in should you make your bed every day, is part of the same habit. And if the room is in a rental, small changes still make a difference to how it feels, as in how to make a rental feel like home.