RESNET® Announces Standards Actions Newly Approved Interim Addendum: MINHERS Interim Addendum 83i, Concrete Masonry Unit Insulation Grading & R-Values Standard ANSI/RESNET/ICC 301-2019, which provides the inspection and calculation criteria for the RESNET HERS® Index rating, does not currently contain a Grade I insulation grading protocol for concrete masonry unit (CMU) wall assemblies that are insulated by filling interstitial cores with flowable foam insulation. This has been confirmed by RESNET SDC 300 in two separate interpretations: IR 301-2019-035 and more recently, IR 301-2022-044. The absence of inspection criteria results in those insulated assemblies being limited to an installation of Grade II or Grade III. To provide these assemblies the same opportunity to achieve Grade I, Interim MINHERS Addendum 83i, adds installation and inspection criteria to the RESNET HERS standards that will allow grading of CMU wall assemblies. The interim addendum also adds criteria in Appendix C to clearly specify “Modeling Assumptions” for thermal properties for various materials, including these concrete masonry unit (CMU) wall assemblies, to improve the consistency and accuracy of rating software simulation of the wall assemblies’ performance. The interim protocols can be used immediately. These insulated CMU assemblies can be simulated using Grade I only where they meet the stated criteria and use the applicable R-values in Appendix C. See Addendum 83i for specifics. Homes where the assemblies cannot be visually inspected in accordance with the new criteria, would be limited to Grade II or Grade III. The interim protocols are required to grade these assemblies Grade I for ratings of homes with Building Permit Dates on or after December 20, 2024. These interim protocols will remain in effect until RESNET’s adoption of the final Addendum 83. It is anticipated that the final protocols will also apply to ratings once they are using Standard ANSI/RESNET/ICC 301-2022. For homes pursuing ENERGY STAR certification, please see the December 18, 2024, “CMU Block Wall ENERGY STAR Policy Updated” notice regarding their temporary allowance for this assembly.
