Roof tent condensation, drying and storage
Wake up to damp walls in a roof tent and it's easy to think it leaks. Usually it's condensation, and most of it comes from you. Here's why it happens, how to cut it down, and how to dry and store a tent so it doesn't go mouldy.
Why condensation happens
TentBox says one person can breathe out up to a litre of water overnight. That moisture is in the air inside the tent, and when it meets the colder tent walls it turns back into water. Two people make twice as much.
Thule adds that moisture from wet clothes and kit, and humid air, condenses on cold walls and the floor too, and can collect under the mattress where you won't see it. Highlander Outdoor, a UK retailer, makes the same point for tents generally: moisture inside isn't always a leak.
Reducing it
- Ventilate, even when it's cold. TentBox and Highlander both say ventilation is the main fix. TentBox suggests leaving the windows open so moisture can escape before it condenses.
- Keep wet things out. TentBox says damp clothes and towels make condensation far worse. Bag them and keep them in the car or under an awning.
- Sleep warm rather than sealing up. TentBox suggests a sleeping bag rated for the temperature and the right clothing in winter, so you're not tempted to close every vent. See sleeping warm in a roof tent.
- Get air under the mattress. Some makers sell a mat for this. Thule's anti-condensation mat is spacer mesh that lets moisture escape from under the mattress, and TentBox's ventilation mat improves airflow under its mattresses in cold weather. Check current price with the retailer.
What to look for in a tent's fabric and ventilation specs is in roof tent specs for UK weather.
Drying after a wet trip
Air the tent out as well as you can before you pack up. Then, TentBox says, if it'll be closed for more than 24 hours, it's very important that it's thoroughly dry first. Open it up on a driveway, in a garage or in an enclosed car park until it is, ideally in the sun.
Don't skip the underside of the mattress. Thule warns that moisture collecting there can lead to mould or mildew if the tent isn't dried properly.
If you're looking at a second-hand tent, check for signs it was put away damp: see buying a used roof tent.
Winter storage
On the car
Whether you leave it on or take it off, the same drying rule applies: make sure it's thoroughly dry before it stays closed. Check your tent maker's guidance on longer-term storage.
Hoists and stands
A roof tent is heavy to lift on and off, so some people store it hanging in a garage. Moby Mountain, a Danish maker, sells a tent lift that raises a roof tent under a garage or carport ceiling for storage and lowers it to the ground for cleaning or drying. It lists a 100 kg maximum load and about 260 cm of lift. Check any hoist's rating against your tent's published weight, and your ceiling height, before you buy.
More in Roof tents
Sources
- TentBox: one person can exhale up to 1 litre of water overnight; ventilation is the main fix, windows open even when cold; keep wet clothes and towels out; air out before leaving; thoroughly dry before closing for more than 24 hours, on a driveway, in a garage or car park; damp left undried causes mould (checked )
- Thule anti-condensation mat: spacer mesh under the mattress lets moisture escape; moisture collects under the mattress and can cause mould or mildew if not dried (checked )
- TentBox ventilation mat: improves airflow under the mattress to reduce condensation in cold weather (checked )
- Highlander Outdoor: moisture inside a tent isn't always a leak; ventilation is the main fix (checked )
- Moby Mountain tent lift, Danish maker: raises a roof tent under a garage or carport ceiling for storage, lowers it for cleaning or drying; 100 kg maximum load, about 260 cm lifting height (checked )