For Reference Only

The R-value calculations on this site are provided for reference and estimation purposes only. Results are based on published R-values for common insulation and construction materials and model code minimums from IECC 2021 and OBC SB-12. They are not a substitute for professional assessment, engineered drawings, or verification with your local building authority.

Building Code

Code minimums shown in this calculator reflect IECC 2021 climate zone requirements and Ontario Building Code SB-12 where applicable. Your local Authority Having Jurisdiction (AHJ) may have adopted a different code edition or local amendments. Actual R-value requirements vary by jurisdiction, assembly type, and project scope.

Always verify compliance requirements with your local building department before finalizing an assembly for a permit application. This tool is not a substitute for a permit application or building inspection.

Accuracy

R-values used in this calculator are based on published manufacturer data and code reference values for typical installations. Actual performance may vary based on installation quality, settling, moisture, thermal bridging, and other field conditions. We make no warranty, express or implied, regarding the accuracy or completeness of any result produced.

If you find an error in a material value or code reference, please contact us so it can be corrected.

Affiliate Links

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No Professional Relationship

Use of this site does not create any professional, advisory, or contractor relationship between you and the operators of R-Value Calculator. The information provided is general in nature and may not apply to your specific project, materials, or jurisdiction.