Drying laundry indoors with the windows shut

A load of washing holds a surprising amount of water, and drying it indoors releases all of it into the room's air. With the windows shut — in winter especially — that moisture condenses on the coldest surfaces: windows, external walls, behind furniture. Given time, the black spots that follow are mould, and they are a health nuisance as well as a decorating one.

Why it backfires

Air can only hold so much water vapour; warm air holds more than cold. Laundry-filled indoor air hits its limit fast, and the excess condenses where the surfaces are coldest — which is exactly where air circulation is worst (corners, wardrobes against outside walls). Mould spores then find their perfect home: damp, still, unventilated.

The fix

Dry indoors deliberately or not at all: one room, window on trickle or open a crack, door shut, radiator off in that room (heating damp air wastes energy), and a dehumidifier if you have one — it pays for itself in drying speed and mould prevention. Outdoors on a line beats everything when weather allows. If a room already shows mould, clean it with a proper mould cleaner per the label, and change the conditions that grew it — cleaning alone just relocates the harvest.

Keep it from happening

Use extractor fans when bathing and cooking and let them run a few minutes after; keep a small gap on trickle vents; leave wardrobe gaps so outside walls can breathe; and add "check behind furniture on outside walls" to the seasonal checklist. The pattern behind all of it: houses stay healthy by exchanging air, and anything that traps moisture — laundry, long showers, sealed windows — needs an exit plan.