Select the right R-value for your project using current IECC 2021 requirements, real-world performance data, and Owens Corning product recommendations.
R-value (thermal resistance) measures a material's resistance to conductive heat flow. Higher R-values indicate greater insulating effectiveness. R-value is measured under steady-state conditions per ASTM C518 at a 75°F mean temperature — the conditions under which Owens Corning products are rated.
Important note on installed performance: Fiberglass batt R-value assumes correct cavity fill, proper batt compression, and no voids or gaps. A correctly installed R-19 batt in a 2×6 cavity will outperform a poorly installed R-21 batt. Continuous insulation layers (FOAMULAR® XPS) are less installation-sensitive because they eliminate cavity gaps.
R-value does not account for air infiltration. In climate zones with significant heating/cooling loads, air sealing should be addressed before or alongside insulation upgrades. The EcoTouch® batt system is compatible with common blower-door-tested air sealing approaches.
| Material | R-value / inch | Product |
|---|---|---|
| Fiberglass Batt | R-3.1 to R-3.8 | EcoTouch® |
| XPS Rigid Foam | R-5.0 | FOAMULAR® |
| EPS Rigid Foam | R-3.6 to R-4.2 | — |
| Mineral Wool Batt | R-3.0 to R-3.3 | — |
| Spray Foam (open) | R-3.5 to R-3.7 | — |
| Spray Foam (closed) | R-5.5 to R-6.5 | — |
Values per ASTM C518 at 75°F mean. Competitor values are industry typical ranges; verify current third-party data before specification.
Based on IECC 2021 residential prescriptive requirements. Commercial and mixed-use requirements vary — contact us for ASHRAE 90.1 guidance.
| IECC Zone | States (Examples) | Attic Min. | Wall (2×4) | Wall (2×6) | Floor | OC Recommendation |
|---|---|---|---|---|---|---|
| Zone 1 | Hawaii, Southern FL | R-30 | R-13 | R-20 | R-13 | EcoTouch® R-30 + R-13 wall |
| Zone 2 | FL, TX Gulf, AZ | R-38 | R-13 | R-20 | R-13 | EcoTouch® R-38 + R-13 |
| Zone 3 | TX, GA, NC, NV | R-38 | R-20 | R-20 | R-19 | EcoTouch® R-38 attic + R-20 wall |
| Zone 4 | TN, VA, KS, OR, WA | R-49 | R-20 | R-21 | R-19 | EcoTouch® R-49 + R-21 (2×6 preferred) |
| Zone 5 | OH, IN, CO, WI, NY | R-49 | R-20+5ci | R-21+5ci | R-30 | EcoTouch® R-21 + FOAMULAR® 1" CI |
| Zone 6 | MN, ND, MT, NH | R-49 | R-20+5ci | R-21+5ci | R-30 | EcoTouch® R-21 + FOAMULAR® 1" CI |
| Zone 7 | AK (Fairbanks), Canada | R-49 | R-20+5ci | R-21+5ci | R-38 | EcoTouch® R-21 + FOAMULAR® 2" CI |
| Zone 8 | AK (Arctic) | R-49 | R-21+5ci | R-21+5ci | R-38 | Custom — contact technical team |
Highlighted rows indicate jurisdictions where continuous insulation is prescriptively required. Local jurisdictions may have adopted more stringent amendments; always verify with the AHJ.
EcoTouch® R-38 (10.25") for most Climate Zones 2-4; R-49 (15.25") for Zones 5-7. Verify ventilation requirements — IECC requires a ventilation channel above attic insulation in vented assemblies.
Request Attic Spec PackageEcoTouch® R-13 fits 2×4 (3.5" cavity); R-19 or R-21 for 2×6 (5.5" cavity). Do not compress batts to fit a shallower cavity — compression reduces effective R-value proportionally.
Request Wall Spec PackageFOAMULAR® XPS at 1" (R-5) to 4" (R-20) provides a thermal break across the structural layer, eliminating the thermal bridging through studs that reduces a 2×6 wall's nominal R-21 to an effective R-14.
Request CI Spec PackageOur technical team can provide a full wall and attic assembly calculation showing effective R-value, thermal bridging corrections, and IECC compliance documentation for your specific climate zone.
Request Free Technical Consultation