R-value requirements vary by state because insulation needs are driven by climate. The International Energy Conservation Code (IECC) assigns each area to a climate zone, and each zone has minimum R-value requirements for new construction.
The IECC uses 8 climate zones across the US. Zone 1 (southernmost Florida, Hawaii) needs minimal insulation. Zone 7–8 (Alaska, northern Minnesota) needs maximum insulation. Most of the continental US falls in Zones 2–6.
Florida (most), Hawaii, southern Texas, southern Louisiana, Arizona (low elevation): Attic R-30, Walls R-13 to R-15, Floors R-13. States: FL (most), HI, TX (far south), AZ (Phoenix area).
Most of Texas, Georgia, Alabama, Mississippi, South Carolina, California (inland): Attic R-38, Walls R-15 to R-20, Floors R-19. States: TX, GA, AL, MS, SC, AR, LA (north), CA (Central Valley).
Virginia, North Carolina, Tennessee, Kentucky, Missouri, Kansas, Colorado (lower elevation), Maryland: Attic R-38 to R-49, Walls R-20, Floors R-19. States: VA, NC, TN, KY, MO, KS, MD, DE.
Ohio, Indiana, Illinois, Pennsylvania, New York, Michigan, Wisconsin, Minnesota, Montana, Idaho, Colorado (mountain): Attic R-49, Walls R-20+, Floors R-30. States: OH, IN, IL, PA, NY, MI, WI, MN, MT, ID, CO, ND, SD, NE, IA.
Northern Minnesota, Alaska: Attic R-49 to R-60, Walls R-25+, Floors R-38. States: MN (northern), AK.
The zone your project is in determines which products you need. We stock the full range — R-11 through R-49 — and can confirm the right R-value for your state when you call. No guessing required.
We supply wholesale fiberglass and mineral wool insulation with next-day delivery across all 50 states. Call us or request a quote online.
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