Dealing with condensation in camper vans

Why condensation happens inside vans

Condensation forms when warm humid air touches a cooler surface and drops water as it crosses the dew point. In vans, metal skin, window glass, and structural ribs often sit far colder than cabin air. At night, breathing, cooking, and even drying damp clothes add moisture. The result can be fogged windows, wet bedding, and mildew in hidden corners.

Several variables drive the problem. Relative humidity indicates how close air is to saturation at a given temperature. Dew point is the temperature where water begins to condense. If interior surfaces fall below that temperature, expect water. Thermal bridging makes this worse, since bare metal conducts exterior cold directly inside, chilling panels and fasteners.

Moisture sources add up quickly. Two sleeping adults can release more than a liter of water overnight through respiration. Open pot cooking, unvented fuel heaters, and wet gear contribute even more. Without steady airflow to replace humid air with drier outside air, moisture accumulates.

Moisture sources you can control

• Keep lids on pots and vent while cooking
• Avoid unvented propane or butane heaters inside
• Hang wet gear in a ventilated area or outside when possible
• Wipe shower spaces immediately after use and run a fan

Cold surfaces and thermal bridges

• Cover structural ribs and posts with insulating materials
• Use thermal break tapes or pads under furring and mounts
• Add insulated window covers to reduce cold glass exposure

Dew point explained simply

Warm air can hold more moisture than cold air. When warm interior air hits a cold surface, it cools, loses capacity, and drops water. The fix is twofold: move moist air out and keep interior surfaces warmer with insulation and thermal breaks.

Field proven ways to prevent moisture buildup

A reliable approach starts with ventilation. A roof fan set to exhaust, paired with a cracked window on the opposite end of the van, creates crossflow that carries moisture out. Run this during cooking and while sleeping. In still, wet weather, a steady low fan setting prevents stale damp air from lingering.

Insulation and air management are the next levers. Quality insulation reduces heat loss and keeps surface temperatures closer to the air temperature, cutting condensation risk. Pair insulation with thermal breaks so metal is not exposed to the interior. Seal unintended air gaps that can channel cold air behind panels where moisture might hide.

Heating helps by raising air temperature and promoting evaporation, but the type matters. Unvented fuel heaters create water vapor as they burn. Vented diesel heaters and electric heat do not add moisture and can keep the shell comfortably above dew point. With a heater on low and a fan moving air out, nights stay clearer and bedding stays dry.

Carry a small hygrometer to guide decisions. Target indoor relative humidity below 50 percent when possible. In rainy or coastal climates, a compact compressor dehumidifier can help when shore power is available. Desiccant packs assist in cabinets and storage nooks but do not replace ventilation.

Ventilation that actually works

• Exhaust out through a roof fan and draw in from a cracked window away from the fan
• Use higher fan speeds during showers and cooking, then taper to low overnight
• Keep airflow paths open behind cabinetry so dead zones do not develop

Insulation and thermal break strategy

• Insulate large panels consistently for even surface temperatures
• Interrupt metal to interior contact with thermal break materials
• Fit snug window covers with reflective cores for both summer and winter

Heating without adding moisture

• Favor vented diesel heaters or electric heat sources
• Keep gentle circulation so warm air reaches corners and under beds
• Do not rely on open flame heaters inside the living space

Night and morning routines that keep mold away

Simple routines matter. Before bed, stow damp items outside the sleeping area and run the fan while the cabin is warm from cooking. Crack a window opposite the exhaust fan to establish a light draw. Close off unneeded openings so airflow follows a clear path across the space.

In the morning, do a quick reset. Squeegee or towel windows, then wring and hang towels to dry where air flows. Lift bedding to release trapped moisture and ventilate the mattress with a slatted base or breathable spacer mesh. Open closet doors for a few minutes to equalize temperature and humidity inside.

Seasonal tactics help. In winter, prioritize insulation continuity and thermal breaks, then use steady low heat with controlled ventilation. In humid summers, airflow becomes king. Keep shades off glass during the day so sun warms the surface above dew point, and vent more aggressively at night when temperatures drop.

Before bed checklist

• Move wet gear to a ventilated spot
• Run the fan on low with a window cracked
• Pre warm the shell if using a vented heater

Morning reset

• Wipe windows and corners where condensation collects
• Air out bedding and under mattress space
• Open cabinets briefly to avoid cool damp pockets

Seasonal tactics

• Winter: continuous insulation and low gentle heat with steady venting
• Summer: maximize airflow, especially overnight and during rain
• Coastal: add dehumidification when power is available

A build planned around moisture control makes all of this easier. Thoughtful fan placement, real thermal breaks behind the finish, and insulated window covers reduce day to day chores and protect the shell long term.

To make that plan real, consider a professional build that bakes in ventilation, insulation, and moisture aware layouts from the start. Our team designs cabins that resist cold bridging, channel airflow where you need it, and stay dry in varied climates. We guide material choices and component placement to keep humidity low and comfort high.

Ready to explore options that fit your travel style? See our Recreational vans, dive into tailored layouts on Custom build vans, or review platforms on Mainstream vans.

Strong builds, clear windows, dry gear. Tell us how you roam, and we will map out a cabin that manages condensation all year while keeping your travels comfortable and safe.

At OZK Customs in Northwest Arkansas, we craft vans for long range adventure, work on the road, and family travel. From ventilation to insulation and power, every system is tuned so the interior stays dry and ready for the next day. Reach out for a plan that fits your routes and your calendar.