Van insulation calculator
A high-roof van has around 30 m² of steel to insulate. This turns your van's real interior dimensions into a shopping list per surface — area with waste, boards or rolls to buy, kilograms added to the payload, and what each choice is worth in R-value.
Pick your van and the numbers below fill themselves from a database of 159 variants.
The cargo box behind the cab: between the walls, floor to ceiling. Pick a van above and these fill themselves.
Insulation per surface
Floor
Walls + rear doors
Ceiling
Insulation to buy
34.7 m²
Shell area
30.9 m²
Added weight
25.2 kg
Estimated cost
≈ 256 €
| Surface | Area | To buy | Packs | Weight | Cost | R-value |
|---|---|---|---|---|---|---|
| FloorPIR / polyiso board · 25 mm | 6.9 m² | 7.7 m² | 3 boards | 5.4 kg | 54 € | 1.32 m²K/WR-7.5 |
| Walls + rear doorsXPS board · 25 mm | 17.1 m² | 19.2 m² | 26 boards | 14.1 kg | 144 € | 0.94 m²K/WR-5.3 |
| CeilingXPS board · 25 mm | 6.9 m² | 7.7 m² | 11 boards | 5.7 kg | 58 € | 0.94 m²K/WR-5.3 |
Buy areas include cutting waste: 12 % for rigid boards, 8 % for Thinsulate, 5 % for wool and foil. Prices are EU street prices (checked Aug 2026), linear in thickness — your supplier's quote wins.
These are the bare shell areas — windows, roof fans and doors are not subtracted, and neither are the ribs and cavities. The VanPlot editor's Shell build-up computes the exact areas with every opening you cut out, and puts the weight straight into your payload.
Insulate your real van in the editor — free →Planning figures, not certification. Standards are summarised for builders; your inspector, your van's plate and your own measurements always win.
How this is calculated
- Surfaces from the van's interior box: floor = length × width; walls = two sides (length × height) plus the rear-door aperture; ceiling = length × width. Pick a van and the box comes from the 159-variant database.
- Buy area = surface × (1 + waste factor for the material); packs = buy area ÷ the material's board or roll size, rounded up.
- Weight = surface × thickness × bulk density; cost = buy area × thickness × the material's price per m² and 10 mm. R-value = 0.18 m²K/W for bare steel and air films + thickness ÷ λ; shown in SI and imperial (× 5.678).
Sources
- Manufacturer datasheets — λ values for XPS, PIR, sheep wool and 3M Thinsulate SM600L
- Build A Green RV — measured insulation tests and moisture chamber results
- FarOutRide — van insulation guide and quantity calculator
Questions builders ask
How much insulation do I need for a camper van?
A high-roof long-wheelbase van (Ducato L3H2, Sprinter 144) has about 30 m² of shell to insulate: ~7 m² floor, ~17 m² walls and rear doors, ~7 m² ceiling. With 12 % cutting waste that is roughly 35 m² of board — about 47 XPS boards (1250 × 600 mm) or 13 PIR sheets (2400 × 1200 mm). A mid-size van is closer to 20 m².
What is the best insulation for a van?
By warmth per millimetre: PIR/polyiso board (λ ≈ 0.022, R-6.5 per inch), then XPS (λ ≈ 0.033, R-4.4), then sheep wool and Thinsulate (λ ≈ 0.04, R-3.4 to 3.8). Boards suit the flat floor and large fields; wool and Thinsulate fill the ribs and curves. Reflectix on its own is about R-1 per inch — a radiant barrier, not insulation.
How much does van insulation weigh?
Little compared with furniture: 25 mm XPS over 31 m² weighs about 26 kg, 25 mm PIR about 24 kg, 50 mm sheep wool about 28 kg. The plywood lining on top usually weighs more than the insulation under it.
Keep reading
Plan the whole van, not just this number
VanPlot is a 3D layout planner for camper conversions. Place real components in your real van and watch weight, axle loads, power and cost update live — this calculator is one panel of it.
Who makes this
I'm Vladimir. I'm planning my own conversion, and none of the tools I tried could tell me whether a layout would fit or what it would do to the rear axle, so I made this one. I work on it alone. If something's wrong or missing, write to me — the address goes to my inbox.
Vladimir Šterjoski