You wake up, reach for the window and your hand comes away wet. The bedding feels clammy, the windows are dripping and there's that faint musty smell that means moisture has been busy all night. If you caravan through an Australian winter, you know the scene.
Condensation is not a leak and it is not bad luck. It is warm, moisture-laden air meeting a cold surface — and in a caravan, every surface is cold at 2 am. The good news is that it is fixable with ventilation, sensible heating and a few daily habits, no rebuild required.
Quick answer
Control airflow, control moisture at the source, and keep surfaces warm. Crack a roof vent overnight, cook with lids on, never dry wet gear inside, avoid unflued gas heaters and keep the van heated to a steady 18-20°C. Do that and the dripping stops.
Why caravans are condensation magnets
A caravan is a small, tightly sealed box. A family of four can release more than 12 litres of water into the air each day just from breathing, cooking and washing. That moisture has nowhere to go, so when the temperature drops at night it condenses on the coldest surfaces — usually single-glazed windows, aluminium walls and the roof.
The problem is worst in Victoria, the ACT, Tasmania and inland NSW, where the gap between warm indoor air and cold exterior panels is biggest. But Queensland and WA vans get it too, especially in humid weather or after the van has been closed up for weeks.
Fix one: ventilate, even when it's freezing
It feels wrong to crack a vent open on a minus-two morning, but a sealed van is a dehumidifier running in reverse. Warm, moist air rises, so roof vents are your best escape route.
- Leave a roof vent cracked overnight — a small, steady airflow beats nothing at all
- Open a window a few centimetres on the opposite side of the van to create crossflow
- Use the rangehood when you cook, and make sure it vents outside, not just recirculates
- Run the bathroom fan after showers and keep the door closed until the steam clears
- Never block vents with gear, pillows or furniture
Fix two: cut moisture at the source
You can't stop breathing, but you can stop making the problem worse.
- Cook with saucepan lids on and avoid long kettle boils
- Dry towels, swimmers and washing outside under the awning, or in park laundry facilities
- If something must dry inside, hang it near an open vent — never against walls or cushions
- Shake out wet shoes and floor mats before they come inside
- Wipe windows down each morning with a microfibre cloth before the moisture soaks into frames
Fix three: heat the van sensibly
Heating helps because warm surfaces don't reach the dew point as easily. But the type of heat matters.
- Use a diesel heater or electric heating to hold a steady 18-20°C rather than blasting hot air in bursts
- Never run an unflued gas heater in a caravan — gas combustion produces water vapour and makes the problem worse
- Close thermal blinds and curtains after sunset to insulate the glass
- Consider an insulated underlay beneath the mattress — the base of the bed is a classic cold spot
Fix four: use a dehumidifier when you can
If the van is on mains power at a caravan park, a small dehumidifier is the most effective tool there is.
- Desiccant units work better in cold conditions; compressor units remove more moisture in warmer weather
- Put moisture absorber tubs in wardrobes, cupboards and under-bed lockers
- A simple digital hygrometer costs about $15 and tells you when you're above the danger zone — keep indoor relative humidity between 30 and 50 per cent
Hidden spaces: where mould actually starts
The windows get the attention, but the damage happens where you can't see it.
- Pull bedding back during the day and lift the mattress occasionally so the base can breathe
- Don't pack cupboards to the brim against exterior walls — leave air space
- Open cupboard doors for a while each day when the van is in use
- During storage, remove damp linen, empty water containers and leave doors and vents slightly open
Real-world tips from a winter touring perspective
- Check seals. Door and hatch seals degrade and let in cold draughts, which makes condensation worse. A $10 roll of seal tape fixes most of it.
- Spot the difference between a leak and condensation. A leak appears in the same spot after rain; condensation appears everywhere on cold mornings. Fix leaks fast — they rot timber and invite mould.
- Clean mould early. Wearing gloves, use a suitable mould cleaner, ventilate the van, then fix the moisture problem — otherwise it comes back.
- Frost on the inside means you're losing heat. If the inside of the glass is icing up, your window is a radiator. Thermal blinds or external window covers make a real difference.
- Don't over-heat. Running the heater flat out in a sealed van just pushes more warm moist air against cold glass. Heat steadily, ventilate constantly.
Powering your dry-out setup
A diesel heater, a dehumidifier and a hygrometer all need reliable 12V power, and most caravan electrical setups weren't built to run them flat out overnight. If your van's battery is struggling to keep up, it's worth looking at your [12V accessories range](https://outcamp.com.au/collections/12v-accessories) — a decent DC-DC charger and the right cabling keep the heater running and the van dry through the coldest nights.
Close
Condensation is not a caravan defect, it's physics — and physics is predictable. Ventilate, manage moisture and keep the van warm, and you'll wake up to dry windows, dry bedding and a van that doesn't smell like a wet towel. Got a trick that works in your van? Drop it in the comments below.
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