Camper van ventilation: preventing condensation

Two people produce about 1-2 litres of moisture per night through breathing and perspiration. Cooking, showering and wet clothes add another 1-3 litres per day. This moisture needs somewhere to go. Without ventilation, this moisture settles on the coldest surfaces: windows, metal walls and corners behind cabinets. This leads to: • Mould growth on walls and furniture • Rust on the body panels (invisible behind insulation) • A damp, musty atmosphere • Health problems from mould spores Good ventilation removes humid air and brings in dry outside air. Combined with insulation (which keeps surface temperatures above the dew point), this is the key to a dry, healthy camper van.

A roof fan is the most important ventilation tool in your camper van. The two most popular brands are: **MaxxFan Deluxe (40×40 cm opening)** Most popular with self-builders. 10 speed settings, rain-resistant (can stay open in rain), built-in thermostat on the Electric model. Power consumption: 0.1A on speed 1 to 2.7A on speed 10 at 12V. Price: €250-€400. **Fiamma Turbo-Vent (40×40 cm opening)** Large 10-blade fan, variable 12V motor, optional thermostat (Polar Control). Slightly cheaper than MaxxFan. Price: €150-€300. Placement: mount the roof fan above the cooking area or in the centre of the camper. Heat and moisture rise, so above the kitchen is most effective. One roof fan is the minimum. For a longer van (L3 or larger), consider a second ventilation point, such as a tilt-and-turn window on the opposite end.

In addition to active ventilation (roof fan), you need passive ventilation openings for constant air circulation, even when the fan is off: • Place ventilation openings low in the camper (bottom of wall or floor) so cool, dry outside air can flow in while warm, humid air exits through the roof fan. • Use insect screens on all openings. • Ventilate cabinets and dead corners — drill small holes (15-20 mm) in the top and bottom of enclosed cabinets so air can circulate. Without this, mould forms behind and inside cabinets. • Leave a gap of 10-15 mm between the back of furniture and the outer wall for air circulation. For vehicle inspection, ventilation openings are mandatory in the living space. The exact requirements depend on your installation (gas requires additional ventilation). With a gas installation, additional requirements apply: the gas compartment must have a ventilation opening of at least 100 cm² at the bottom, with a direct connection to the outside.

Even with good ventilation and insulation, you may still experience condensation. Here are proven solutions: 1. Run the roof fan while cooking — cooking steam is the biggest source of moisture. Set the fan to extract (blowing air out), not intake. 2. Dry wet clothes outside or in a sealed space with ventilation to the outside — not in the living area. 3. After sleeping, drive for 10-15 minutes with the heater on and a window open — this dries out the camper quickly. 4. Use a moisture absorber (e.g. CaCl₂ granules) in enclosed cabinets and under the bed as a backup, but don't rely on it as your only measure. 5. Insulate all metal surfaces — every uninsulated piece of metal becomes a condensation point. Pay extra attention to wheel arches, door posts and window frames. 6. Cook with a lid on the pan — this reduces steam release by 70-80%. 7. Consider a hygrometer (humidity meter) — keep relative humidity below 60%. Above 70%, mould growth becomes inevitable.