Thinsulate vs Foam Board Insulation for a Van
Thinsulate vs foam board for van insulation: R-value per inch, fit around ribs and curves, moisture, weight, sound and which goes where in a camper build.
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Use both: foam board where surfaces are flat and you want the most R per inch (floor and roof panels), and Thinsulate where it has to follow ribs and curves (walls, doors, wheel arches). DOE lists XPS at R-5.0 and polyiso at R-5.6 to R-8 per inch; Thinsulate SM600L's listings give about R-3.5 to R-5.45 per inch.
Side by side
| Thinsulate SM600L | Foam board (XPS or polyiso) | |
|---|---|---|
| R per inch | About 3.5 to 5.45 (listings disagree) | XPS 5.0; polyiso 5.6 to 8 (DOE) |
| Fit | Flexible, follows curves | Rigid, flat surfaces only |
| Moisture | Hydrophobic (listing) | XPS resists moisture well (DOE) |
| Weight | About 0.15 lb per sq ft (listing) | Varies by board |
| Sound | Sold as an acoustic absorber | Little |
Heat
Heat flow through a layer falls as R rises (HyperPhysics' conduction relation), and DOE notes R-values add up. Two inches of XPS gives about R-10; 1.5 inches of Thinsulate about R-5.2 by the lower listing.
Fit and gaps
A rigid board leaves gaps against curved metal, and gaps lose heat. Thinsulate fills irregular cavities; Second Skin's listing calls it conformable.
Who should use which
- Foam board: floors, flat roof sections, under the bed.
- Thinsulate: walls, doors, curved roof edges, around wheel wells.
More in best van insulation and how to insulate a van.
Frequently asked questions
Is Thinsulate better than foam board for a van?
For curved walls and doors, yes. For flat floors and roof panels, foam board gives more R per inch by DOE's figures.
What R-value is foam board?
DOE lists XPS at R-5.0 per inch, polyiso at R-5.6 to R-8 and EPS at R-3 to R-4.
Can you use foam board on van walls?
On flat sections, yes, but rigid board leaves gaps against ribs and curves, which a flexible material fills better.
Does Thinsulate absorb moisture?
Its sellers describe it as hydrophobic. Check 3M's data sheet for the current figures.
Which is quieter, Thinsulate or foam?
Thinsulate SM600L is sold as an acoustic absorber; rigid foam does little for road noise.
Sources
- Energy Renovations: Insulation, A Guide for Contractors to Share with Homeowners (PNNL-20972), U.S. Department of Energy
- Heat Conduction, HyperPhysics (Georgia State University)
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