How much insulation does your van need?
Pick your van to estimate the walls, ceiling, doors and floor, minus the windows. Then see how many rolls, boxes, boards or kits to buy, the R-value you’ll get and an example cost. Every area can be edited.
Measure, then pick a material.
The example is a Sprinter 144″ high roof with one window, Thinsulate on the walls and ½ in XPS under the floor. Change anything.
AYour vehicle
We estimate each surface from the inside size of the model you pick.
BSurfaces to insulate
Every number is editable. Untick anything you won’t insulate. The working is shown under each one.
2 × 133 in × 79.1 in − door (51.5 in × 79.1 in) − windows (510 sq in) ÷ 144 = 114.3 sq ft
51.5 in × 79.1 in ÷ 144 = 28.3 sq ft
133 in × 70.1 in ÷ 144 = 64.7 sq ft
70.1 in × 79.1 in ÷ 144 = 38.5 sq ft
70.1 in × 79.1 in ÷ 144 = 38.5 sq ft
Add any extra areas you plan to insulate.
133 in × 70.1 in − wheel wells (36 in × 17 in) ÷ 144 = 60.5 sq ft
Walls, doors and ceiling: 245.8 sq ftFloor: 60.5 sq ft
CMaterials
R-value tells you how well a material slows heat. Higher is better.
DPrices
Example prices so the totals aren’t empty. They are not current prices: type what your supplier charges.
Every wall material in the same 1½ in space
Each row uses the thickest standard product that fits your space, for the same 245.8 sq ft of walls, doors and ceiling, plus 15% extra. R-values are for the material alone: in a van, metal ribs and gaps lower the real result. Costs use example prices.
| Material | Thickness | R-value | Amount to buy | Example cost |
|---|---|---|---|---|
| 3M Thinsulate SM600L | 1½ in | R‑5.2 | 57 linear feet | USD 684USD 12 per linear foot |
| Havelock Wool van batts | 2 inThicker than your space | R‑7.8 | 3 boxes (100 sq ft each) | USD 642USD 214 per box (100 sq ft) |
| Polyiso rigid board | 1½ in | R‑9.6 | 9 boards (4 × 8 ft) | USD 342USD 38 per board (4 × 8 ft) |
| XPS foam board | 1½ in | R‑7.5 | 9 boards (4 × 8 ft) | USD 405USD 45 per board (4 × 8 ft) |
| Closed-cell spray foam kit | 1½ in | R‑9.3 | 1 kit (650 board ft) | USD 900USD 900 per kit (650 board ft) |
| Mineral wool board | 1½ in | R‑6.3 | 6 packs (2 × 4 ft boards) | USD 480USD 80 per pack (2 × 4 ft boards) |
How this works
- Side walls = 2 × inside length × inside height − the side door opening − windows.
- Side door = door width × inside height. Ceiling = length × width. Rear doors = width × height. Floor = length × width − the wheel wells.
- Amount to buy = area × (1 + waste %) ÷ what one roll foot, box, board or pack covers, rounded up. Spray foam: area × thickness = board feet, then ÷ the kit size.
- R-value = R per inch × thickness, using each maker’s published figures. In metric, RSI = R × 0.176.
Door sizes are estimated from the door width and the inside height, and vans have curved walls, ribs and wheel wells, so treat the areas as a starting point. Measure your own van if you can, and type the numbers in. The vehicle sizes come from manufacturer and body-builder spec sheets and measured conversion guides, collected in September 2026; skoolies, box trucks, trailers and truck beds use typical sizes.
The materials
- 3M Thinsulate SM600L: R-3.5 per inch. 60 in wide roll, sold by the foot (5 sq ft per foot); about 1.5 in thick, R-5.2 per layer. Source: 3M Thinsulate spec sheet (via Second Skin) and 3M technical data sheet.
- Havelock Wool van batts: R-3.9 per inch. 2 in batts, 100 sq ft per box. Source: Havelock Wool product page.
- Polyiso rigid board: R-6 per inch. 4 × 8 ft boards (32 sq ft); R-6.0 at 1 in. Source: Rmax Thermasheath data sheet.
- XPS foam board: R-5 per inch. 4 × 8 ft boards (32 sq ft). Source: Owens Corning FOAMULAR 150 data sheet.
- Closed-cell spray foam kit: R-6.2 per inch. Kits rated in board feet (1 sq ft × 1 in); 200 and 650 board-foot kits. Source: DuPont Froth-Pak product pages.
- Mineral wool board: R-4.2 per inch. ROCKWOOL Comfortboard 80, 2 × 4 ft boards; 80 / 48 / 40 sq ft per pack at 1 / 1½ / 2 in. Source: ROCKWOOL Comfortboard 80 product page.
For the floor, XPS and polyiso boards go under the plywood subfloor. 3M’s own data sheet for SM600L lists thickness and weight but no R-value; the R-5.2 figure comes from the 3M Thinsulate spec sheet that its retailers publish. Polyiso’s R-value is measured at 75 °F and can drop in very cold weather. The FOAMULAR 150 data sheet lists boards from 1 in up; for the thinner ½ and ¾ in XPS floor boards, this tool uses the same R-5 per inch, which is on the low side (Owens Corning labels its ½ in board R-3).
Three things that matter as much as R-value
- Moisture and vapour barriersBreathing and cooking put a lot of water in the air, and it condenses on cold metal. Closed-cell spray foam and foam boards slow vapour on their own; with batts or wool, many builders add a vapour barrier on the warm side. Don’t trap water between two barriers.
- Thermal bridgingMetal ribs and screws carry heat straight through. Cover ribs with a thin layer of insulation or a strip of foam before the panels, and use wooden furring strips rather than metal.
- VentilationInsulation can’t fix damp air. A roof fan and a cracked window move moisture out, even in winter. Always ventilate when you use a gas stove or heater, and fit a carbon monoxide alarm.
Sources
- 3M Thinsulate Acoustic Insulation SM600L technical data sheet (42 mm thick; no R-value listed)
- 3M Thinsulate spec sheet, as published by Second Skin (SM600L: 1.5 in nominal, R-5.2, about R-3.5 per inch)
- Second Skin SM600L product page (sold 60 in wide, by the linear foot)
- Havelock Wool van insulation (2 in batts, R-3.9 per inch, 100 sq ft per box)
- Rmax Thermasheath product data sheet (polyiso R-values by thickness, ASTM C518)
- Owens Corning FOAMULAR 150 XPS data sheet (R-5 per inch; 4 × 8 ft boards)
- Owens Corning FOAMULAR NGX ½ in × 4 × 8 ft board, labelled R-3 (Home Depot listing)
- DuPont Froth-Pak 200 closed-cell foam (R-6.2 per inch aged; about 200 sq ft at 1 in; yields measured in lab conditions)
- DuPont Froth-Pak 650 spray foam insulation kit
- ROCKWOOL Comfortboard 80 (R-4.2 per inch; sq ft per pack by thickness)
- US Department of Energy, Energy Saver: insulation and R-values
Prices on this page are examples to edit, not current prices. Check fire ratings and the maker’s instructions for anything you put in a vehicle.
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