Side-by-side specs
| Spec | Rigid Foam Board | Spray Foam |
|---|---|---|
| R-value per inch | R-3.6 (EPS) to R-6.5 (polyiso) | R-3.5 (open) to R-7 (closed) |
| Cost per sq ft | $0.40–$2.00 (DIY) | $1.00–$5.00 (installed) |
| Air sealing | Only at sealed seams | Built-in |
| Best for | Continuous exterior insulation, basement walls, slab edge | Cavity insulation, crawl spaces, rim joists, complex geometry |
Rigid Foam Board
Pros
- Lower material cost per R-value
- Predictable thickness and R-value
- Good DIY option for basement walls and exterior continuous insulation
- Easy to cut and patch
Cons
- Seams need taping/foaming to air-seal
- Won't fill irregular cavities
- Polyiso loses R in very cold conditions
Spray Foam
Pros
- Air seals and insulates in one step
- Conforms to any shape
- Highest installed R-value per inch
- Adds rigidity
Cons
- Higher installed cost
- Requires licensed installer
- Harder to modify later
Which should you pick?
- Insulating a basement wall yourself: Go with Rigid Foam Board. Foam board on the inside, taped seams, then framing — proven DIY.
- Insulating a vaulted ceiling with skylights and wiring: Go with Spray Foam. Spray foam handles the obstructions; boards won't.
- Adding continuous insulation outside the wall sheathing: Go with Rigid Foam Board. That's what rigid boards are designed for.
Frequently asked questions
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- Batt vs. Blown-In Insulation
- See all insulation comparisons
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Local pricing and licensed contractors for Spray Foam in these metros.
Spray Foam in Rochester, NYSpray Foam in Buffalo, NYSpray Foam in Raleigh, NCSpray Foam in Philadelphia, PASpray Foam in Orlando, FLSpray Foam in Minneapolis, MNSpray Foam in Oklahoma City, OKSpray Foam in Madison, WI
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