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Insulation R-value
Total assembly R-value by stacking layers. Common insulations, sheathing, and finish materials covered. Useful for IECC compliance sanity-checks.
inR = 12.3
inR = 0.6
inR = 0.3
Assembly R-value
R-13.2
Sum of (R/in × thickness) across all layers.
Excludes air-film + framing-effect adjustments. For IECC Manual U/F-factor compliance, use a Building Energy Codes Program-approved REScheck or COMcheck output. This is a ballpark.
R-per-inch reference values
- Closed-cell spray foam: R-6 to R-7
- Open-cell spray foam: R-3.5 to R-4
- Polyiso rigid: R-6 to R-6.5
- XPS rigid: R-5
- EPS rigid: R-3.8 to R-4.4
- Fiberglass batt: R-3.1 to R-4.3
- Mineral wool batt: R-3.7 to R-4.2
- Cellulose: R-3.7
- OSB / plywood sheathing: R-1.25/in
- Drywall: R-0.45/in
Built by Forward
Forward runs R-value calcs, HVAC load, ventilation CFM, and the full NEC/IBC/IMC/IPC catalog over text. Project lookups against Procore + Autodesk + OneDrive.