Condensation and Mould in Campervans: Causes and Cures

Open a campervan that's been closed up for a week in a British autumn and you'll often find condensation running down the windows and a faint musty smell. That moisture is the fuel for mould, which not only stinks but is genuinely unpleasant to live with and can damage interior panels. The good news is that the causes are well understood and easy to fix.

Where the moisture comes from

A surprising amount of water vapour is produced in a small space:

• Breathing: two people sleeping in a van produce around a litre of moisture overnight.
• Cooking: boiling a kettle and cooking on the hob release steam directly into the air.
• Gas: burning gas produces water vapour as a by-product of combustion.
• Drying clothes, wet coats and dog walks all add their share.

In a house, that moisture has room to disperse. In a van, it hits a cold window or panel, cools and condenses back into liquid water.

The cures — ventilation first

Ventilation is the cheapest and most effective fix:

• Keep a roof vent or window cracked open overnight, even in winter.
• Use the extractor or hob lid while cooking and for a few minutes after.
• Open windows fully when you arrive on site so the van can breathe out.
• On a wet day, ventilate more, not less.

Beyond airflow, absorb the moisture: moisture traps with silica or calcium chloride cost £5-£15 and work well in cupboards and under the bed. A small 12V or mains dehumidifier is the heavy-duty option for a damp winter.

Cleaning mould safely

If mould has taken hold, don't just paint over it — the spores will come straight back through the paint. Treat the surface with a mould and mildew cleaner or a dilute white vinegar solution, scrub, then dry the area thoroughly before anything is sealed again. Wear gloves and keep the van ventilated while you work.

Preventing the return

• Never store damp bedding or towels in the van.
• Take wet coats and boots outside or dry them before stowing.
• Check the mattress base and the area under the seats — the coldest, most humid spots.
• Address any actual leaks quickly, because leaks and condensation together are a fast route to rot.

Tip: in winter, a couple of moisture traps plus a cracked vent will keep a parked van dry far better than a fully sealed one.

Keeping moisture out is the best way to avoid the damp damage covered in our damp check guide. A dry, fresh-smelling van is also a far better advert when you come to sell — see the standard on motorhomes for sale.