Myth or Fact: Is Drying Laundry Indoors Overnight Without Ventilation Bad for Your Home?
One load of wet washing releases about two litres of water into the air. Here is what researchers found, and how to dry clothes indoors without inviting mould.
By Sophie LaurentDesign & Garden Editor
In winter, the drying rack moves inside. It goes in the bedroom, next to the radiator, or in the living room overnight with the windows shut to keep the heat in. The warning you may have seen online is blunt: never dry laundry indoors overnight without opening a window.
Drying clothes indoors is often unavoidable in cold, wet weather, and it is not a problem in itself. The problem is doing it in a sealed room, night after night.
How much water are we talking about?
More than most people think. Researchers at the Mackintosh Environmental Architecture Research Unit at the Glasgow School of Art studied laundry habits across a wide mix of homes in the west of Scotland. They found that an average load of washing releases around 2 litres of moisture into the air as it dries. Draped on airers by radiators in poorly ventilated rooms, it can account for up to a third of the moisture in the air (Glasgow School of Art).
The same study of 100 homes, reported by the BBC, found that 87% of households dried their washing indoors in colder weather, and that 75% had moisture levels that could support dust mites. The researchers also found a strong association between drying laundry indoors and mould spores (BBC News).
Why overnight in a closed room is the worst case
At night the windows are shut, the heating may switch off, and walls and window panes cool down. Warm, moist air meets those cold surfaces and the water condenses. Repeat that every night and you get black spots in window corners, behind furniture and inside wardrobes.
UK government guidance on damp and mould explains that they mainly affect the airways and lungs, and that children, older adults and people with certain health conditions are at greater risk (GOV.UK). The US Environmental Protection Agency puts it simply: the key to mould control is moisture control (US EPA). It recommends keeping indoor humidity below 60%, ideally between 30% and 50%.
How to dry clothes indoors without the damp
- Pick one room and close the door. A bathroom with the extractor fan running is ideal, because it stops the moisture spreading through the house.
- Give the moisture a way out. Open the window a little, or open the trickle vents if you have them.
- Use a dehumidifier. In a closed room it collects the water the clothes release, and many models have a laundry setting.
- Don't dry clothes directly on radiators. Local councils in the UK advise against it in their damp guidance (South Kesteven District Council).
- Spin well. A faster final spin leaves less water in the fabric to begin with.
- Check your dryer. A vented tumble dryer should vent outside, and a condenser dryer still needs a ventilated room.
The bottom line
Drying clothes indoors is fine. Doing it in a sealed bedroom every night is what causes trouble. Give the moisture a way out with a window, a fan or a dehumidifier, and keep an eye on your window corners. Condensation every morning is your home telling you the air is too wet.
Sources
- The Glasgow School of Art, Research highlights health and economic problems caused by our indoor drying habits (2012)
- BBC News, Indoor laundry drying "poses a health risk" (2012)
- GOV.UK, Understanding and addressing the health risks of damp and mould in the home
- US Environmental Protection Agency, A Brief Guide to Mold, Moisture and Your Home
- South Kesteven District Council, How can I reduce damp and mould?
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