Open Cell vs Closed Cell Spray Foam: R-Value and Cost for a Surprise Home
The two foams differ in R-value, price and the surfaces where they work best. Open-cell gives R-3.5 to R-3.7 per inch, and closed-cell gives R-5 to R-7 per inch. R-value per inch is the figure that sets how much depth a surface needs, and the table shows typical prices for each surface with the foam choice noted.
| Job | Typical price | Key variables |
|---|---|---|
| Spray foam, attic floor | $1,100 to $6,800 | open-cell for depth, closed-cell for tight access, thickness |
| Spray foam, attic rafters or roof deck | $1,500 to $9,000 | closed-cell on the deck, roof size, vents |
| Spray foam, existing walls | $3,200 to $8,800 | open-cell in deep cavities, wall area, siding |
| Spray foam, garage walls | $2,600 to $8,900 | foam type, wall height, garage size |
| Spray foam, whole house | $4,000 to $26,000 | mix of open-cell and closed-cell, surfaces covered |