Damp matress

Sounds like the mattress is sweating. You have a warm humid interior and colder side walls to the caravan, so condensation is forming. The mattress needed chance to air before the van was closed up.

When you store over winter take all bedding materials, towels etc out and into the house. Hinge all bed bases, mattresses and seats up, making sure they do not touch the van sides. Open all cupboard doors to allow air circulation.

Do not bother with a dehumidifier or small heater on a timer, just make sure you can get some air circulation through the van.

Colin

I am guessing that your caravan is relatively new ?, on older caravans, i have a 2008 Coachman there is an additional board that sits approx 1 inch from the outer wall of the caravan, this is to stop what your are now experiencing, it stops bedding etc coming into contact with the outside wall which gets very cold especially during the Autumn and Winter months, and helps to alieviate the damp you are now experiencing.

Hello Rufs, it's not just older caravans that have that feature, my 2022 Coachman has it fitted. It also lets the warm air from the radiators under the bed and settees to circulate through the living areas.

Ok! maybe Coachman are a tad more upmarket ?I have seen new caravans without this feature which seems to me to be a cost cutting exercise that could cost you money further down the line.

If you have Alde heating having a board 25mm approx off the walls is part of heating cycle it allows heated air to rise up the wall should also enter overhead lockers  then drop down as will have cooled to start cycle over again try to keep moisture down by not allowing kettle etc to boil longer than needed & have windows open on ventilation setting to get air flow

Good idea in winter caravanning is to keep all bedding away from outside walls