How-to · 4 min read · Updated 6 November 2026
Drying clothes indoors without causing mould: a practical guide
How much moisture washing adds
Every kilogram of wet washing has to lose its water somewhere. Research by the Mackintosh School of Architecture found that drying a load indoors can release up to about 2 litres of water, and that indoor drying can account for a large share of the moisture in a home during the colder months. For a family drying several loads a week on radiators and airers, that is many litres of water each week being added to air that is already damp from showers, cooking and breathing.
That moisture spreads through the house and condenses on the coldest surfaces it finds, usually windows, external wall corners and the backs of wardrobes. It is a big reason homes that are mould-free in summer get black spots by January.
Best and worst places to dry washing
| Location | Mould risk | Notes |
|---|---|---|
| Outside on a line | Very low | Even on cool, breezy days washing dries well |
| Vented or heat pump tumble dryer | Low | Condenser models need emptying; vented ones must vent outside |
| Utility room or bathroom, door shut, fan on or window open | Low to medium | Contain the moisture and remove it at source |
| Room with a dehumidifier running, door shut | Low to medium | Dehumidifier collects the water and speeds drying |
| Airer in a living room | Medium to high | Moisture spreads through the house |
| Directly on radiators | High | Blocks heat and releases moisture fast, often into bedrooms |
| In a bedroom overnight | High | Adds to moisture from breathing in a closed room |
Step-by-step: drying indoors the right way
- Use the highest spin speed the fabrics allow, so less water goes on the airer
- Choose one room and keep its door shut
- Run the extractor fan or open the window a few centimetres
- Or run a dehumidifier in the room on a laundry setting
- Space items out on an airer rather than piling them up
- Keep the airer away from walls and furniture
- Empty the dehumidifier tank and wipe any condensation from windows afterwards
- Avoid putting damp items away in wardrobes before they are fully dry
Dehumidifiers and heated airers compared
A dehumidifier in a small closed room is one of the most effective ways to dry washing without adding moisture to the house, because it removes the water and collects it in a tank. Compressor dehumidifiers tend to be efficient in warmer rooms, while desiccant models work better in cold rooms and garages. Many households find that running one on laundry days costs less than running a tumble dryer.
Heated airers dry clothes faster but still release all the moisture into the room, so they need the same ventilation as an ordinary airer. Using one in a bathroom with the fan running, or alongside a dehumidifier, gives the best of both.
Tumble dryer tips
Vented tumble dryers must have their hose run outside through a wall or window vent, not left blowing into a utility room. Condenser and heat pump models collect water in a tank or plumb it into a drain, but they still release some warmth and moisture, so a little ventilation helps. Clean the lint filter every time and the condenser unit as the manual recommends, or drying times and moisture escape both increase.
Landlords and flats with no outdoor space
Many flats have no balcony or garden and no space for a dryer, so tenants often have little choice but to dry indoors. Government damp and mould guidance says landlords should not blame mould on lifestyle and should look at whether the home has adequate ventilation and heating. Providing a working extractor fan, trickle vents, space for a dryer or a dehumidifier, and a clear explanation of how to use them is usually cheaper than repeated mould treatment between tenancies.
Common mistakes on laundry day
- Draping wet towels and clothes over bedroom radiators overnight
- Drying washing in the living room with every window shut
- Leaving a full load in the drum for hours, which smells and adds time to drying
- Putting slightly damp clothes away in wardrobes on external walls
- Running a dehumidifier with the room door wide open, so it tries to dry the whole house
- Forgetting to clean the lint filter and condenser in a tumble dryer
- Blocking trickle vents with airers and curtains
Small changes such as a faster spin, one dedicated drying room and a closed door make a noticeable difference to condensation within a week or two.
Frequently asked questions
Is it bad to dry clothes on radiators?
Drying clothes on radiators releases moisture quickly, blocks heat from reaching the room and can make condensation and mould worse, especially in bedrooms. If you have no alternative, do it in one room with the door shut and a window open or a dehumidifier running, and keep it to rooms where nobody sleeps.
Does a dehumidifier stop mould from drying washing?
A dehumidifier running in a closed room with the washing removes much of the water the clothes give off, so far less moisture spreads to other rooms. It is one of the most effective options for homes without outdoor space. It does not replace working extractor fans and will not help with a leak or penetrating damp.
Can I dry clothes in the bathroom?
A bathroom can be a good place to dry washing if it has a working extractor fan or an openable window, and the door is kept shut so moisture does not spread. Make sure the fan runs for long enough, and wipe down any condensation afterwards to protect sealant and grout from mould.
laundry condensation dehumidifier how-to
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