Camper van insulation: materials, R-value and tips

An uninsulated van is essentially a metal box. In winter it cools down extremely fast, in summer it becomes an oven. Without insulation: • You lose up to 10× more heat than in an insulated van • Moisture from the air condenses on the cold metal walls • Water in pipes freezes in winter • It becomes uncomfortable above 25°C outside temperature Condensation is the biggest danger: moisture creeps between insulation and bodywork causing rust. This is invisible until it's too late. Good insulation with a vapor barrier prevents this.

The four most commonly used materials for camper van insulation: Armaflex (or similar closed-cell rubber): by far the most popular. Easy to work with, vapor-resistant, flexible. Thermal conductivity (λ): 0.033–0.038 W/mK (19 mm = R 0.53). Price: €15-€25 per m². XPS (extruded polystyrene, e.g. Jackodur): rigid boards, high compressive strength, moisture resistant. Ideal for floors. Thermal conductivity (λ): 0.029–0.036 W/mK (30 mm = R 0.86). Price: €5-€10 per m². Rock wool/glass wool: cheap with good insulation value, but absorbs moisture. Only use with proper vapor barrier. Thermal conductivity (λ): 0.032–0.040 W/mK (50 mm = R 1.38). Price: €3-€7 per m². Reflective foil (e.g. Dodo): thin foil with reflective layer. Limited insulation value as sole layer, but good as supplement. Thermal conductivity (λ): >0.040 W/mK, works mainly by reflecting radiant heat.

The required insulation thickness depends on your climate and travel pattern: Summer only in Southern Europe: 10-15 mm Armaflex is sufficient. It's mainly about blocking heat and preventing condensation. Three-season in Western Europe: 19-25 mm Armaflex or equivalent. This is the sweet spot for most camper vans. Four-season including winter: 25-40 mm total insulation thickness. Combine materials: XPS on the floor (20-30 mm), Armaflex on walls and ceiling (19-25 mm). Keep in mind the loss of interior space. With 25 mm insulation on all sides, you lose about 5 cm in width and 2.5 cm in height. Measure this beforehand!

1. No vapor barrier: moisture from the air condenses on the cold metal behind the insulation. Use closed-cell material (Armaflex) or apply a vapor barrier. 2. Forgetting thermal bridges: everywhere metal runs from outside to inside (screws, ribs, window frames) you lose heat. Insulate these points too. 3. Skipping wheel arches: wheel arches are a huge surface area directly exposed to outside air. Insulate them carefully. 4. Not insulating the floor: you lose a lot of heat through the floor, especially when parked on asphalt. Use XPS boards of at least 20 mm. 5. Insufficient ventilation: insulation without ventilation leads to moisture problems. Install a roof vent fan and ventilation openings.