How does the insulation calculator work?
The insulation calculator works out how much insulation material you need for your van. The tool accounts for windows, doors and cutting waste per material type, so you know exactly how many rolls or panels to order.
Surface area calculation
The gross wall area is calculated as: (2 × length × height) + (width × height). These are the two side walls plus the rear wall — the front wall (bulkhead) is excluded because it is usually not insulated. The area of windows and doors is subtracted based on the percentage you specify. Optionally, the floor and ceiling are included.
Cutting waste per material
Each insulation material has a different waste percentage. Mineral wool (rock or glass wool) is flexible and has only 5% waste. PIR and XPS rigid boards are stiff and break at irregular shapes: 12%. Armaflex (rubber foam) sits in between at 8%. Reflective foil is easy to cut to size: 5%. The total including cutting waste determines how much you actually need to buy.
Calculating rolls and panels
The number of rolls or panels is calculated by dividing the total area including cutting waste by the area per roll or panel, then rounding up. This way you always order enough material without buying too much.
Frequently asked questions
How much cutting waste should I allow for?
This depends on the material and the shape of your van. Flexible materials like wool and Armaflex have 5–8% waste. Rigid boards (PIR, XPS) have 10–15% waste due to the irregular shapes around wheel arches, ribs and cable pass-throughs. When in doubt, add a little extra.
Which insulation material is best for a camper van?
There is no single 'best' material. Armaflex is popular for its thin profile and built-in vapour barrier. PIR boards insulate best per centimetre (low lambda value). Rock wool is cheap and fire-resistant but needs a vapour-tight finish. A combination is often used: PIR on large flat surfaces and Armaflex in cavities.
Should I insulate the floor and ceiling?
Yes — for a comfortable interior climate, insulating both the floor and ceiling is important. The roof loses the most heat (warm air rises). The floor prevents cold from below, especially in winter. Without full insulation, you get cold bridges and condensation.
How much waste should I calculate?
Add 10-15% extra for insulation material and 5-10% for boards. With complex shapes (wheel arches, curves) it can go up to 20%.
What material is best for the walls?
Birch plywood (3-4mm) is the most popular choice: light, strong and easy to finish. Cork and fabric are alternatives if you want to save weight.