US BUILDING DEPARTMENT CODE REFERENCE · UPDATED OCTOBER 2026
50-State IECC Energy Code & Design Temperature Schedule
Verify your state's baseline residential energy code, IECC climate zones, prescriptive insulation R-values, fenestration limits, and 99%/1% outdoor design temperatures.
| State | Adopted Residential Energy Code | Zones | Ceiling | Wood Wall | Window U | SHGC | 99% Win / 1% Sum | Order |
|---|---|---|---|---|---|---|---|---|
| Alabama (AL) REScheck & Manual J accepted statewide. | 2015 IECC (Alabama Residential Energy Code) | 2A, 3A | R-38 | R-13 | 0.35 | 0.25 | 23°F / 94°F | Order → |
| Alaska (AK) High-latitude heating loads govern. | 2018 IECC / Alaska BEES | 7, 8 | R-49 | R-20+5ci | 0.30 | 0.40 | -18°F / 73°F | Order → |
| Arizona (AZ) Phoenix/Tucson enforce strict SHGC <= 0.25 and AED solar checks. | 2018 / 2021 IECC (Adopted by Municipality) | 2B, 3B, 4B, 5B | R-38 | R-13 | 0.40 | 0.25 | 36°F / 108°F | Order → |
| Arkansas (AR) REScheck UA trade-off accepted statewide. | 2014 Arkansas Energy Code (2009 IECC base) | 3A, 4A | R-38 | R-13 | 0.35 | 0.30 | 20°F / 96°F | Order → |
| California (CA) CA requires Title 24 CF1R for energy; ACCA Manual J is accepted for HVAC sizing. | CA Title 24 Part 6 (CEC Software Required) | 3B, 3C (CA Zones 1–16) | R-38 | R-21 | 0.30 | 0.23 | 38°F / 92°F | Order → |
| Colorado (CO) Denver & Front Range cities strictly enforce 2021 IECC + Manual J/S. | 2021 IECC (Statewide Minimum / Local 2024 IECC) | 4B, 5B, 6B, 7 | R-60 | R-20+5ci or R-13+10ci | 0.30 | 0.40 | 1°F / 92°F | Order → |
| Connecticut (CT) REScheck-Web 2021 IECC & Manual J required for permits. | 2021 IECC (2022 CT State Building Code) | 5A | R-60 | R-20+5ci | 0.30 | 0.40 | 7°F / 88°F | Order → |
| Delaware (DE) REScheck & Manual J accepted in New Castle, Kent & Sussex counties. | 2018 IECC | 4A | R-49 | R-20 or R-13+5ci | 0.32 | 0.40 | 15°F / 90°F | Order → |
| District of Columbia (DC) Dedicated DC code profile in REScheck-Web. | 2017 DC Energy Conservation Code | 4A | R-49 | R-20 or R-13+5ci | 0.32 | 0.40 | 18°F / 93°F | Order → |
| Florida (FL) ACCA Manual J + S required statewide; prescriptive FL REScheck supported. | Florida Building Code 8th Ed. (2023 Energy Conservation) | 1A, 2A | R-38 | R-13 | 0.40 | 0.25 | 40°F / 93°F | Order → |
| Georgia (GA) REScheck + Manual J widely required across Metro Atlanta and statewide. | 2015 IECC with Georgia State Supplements | 2A, 3A, 4A | R-38 | R-13 | 0.35 | 0.25 | 23°F / 93°F | Order → |
| Hawaii (HI) Tropical solar heat gain (SHGC <= 0.25) is primary check. | 2018 IECC with Hawaii Amendments | 1A | R-30 | R-13 | 0.50 | 0.25 | 61°F / 89°F | Order → |
| Idaho (ID) REScheck & Manual J required for residential permits. | 2018 IECC with Idaho Amendments | 5B, 6B | R-49 | R-20 or R-13+5ci | 0.30 | 0.40 | 6°F / 95°F | Order → |
| Illinois (IL) Statewide 2021 IECC mandate with Illinois amendments. | 2021 IECC (Illinois Energy Conservation Code) | 4A, 5A | R-49 | R-20 or R-13+5ci | 0.30 | 0.40 | 0°F / 90°F | Order → |
| Indiana (IN) REScheck & Manual J accepted in all Indiana counties. | 2020 Indiana Residential Code (2009/2018 IECC base) | 4A, 5A | R-49 | R-20 or R-13+5ci | 0.32 | 0.40 | 4°F / 89°F | Order → |
| Iowa (IA) REScheck-Web 2012/2018 IECC & Manual J accepted. | 2012 IECC (Statewide Residential) | 5A, 6A | R-49 | R-20 or R-13+5ci | 0.32 | 0.40 | -5°F / 90°F | Order → |
| Kansas (KS) Johnson/Sedgwick counties require REScheck & Manual J. | 2018 / 2021 IECC (Adopted Locally) | 4A, 5A | R-49 | R-20 or R-13+5ci | 0.32 | 0.40 | 5°F / 97°F | Order → |
| Kentucky (KY) REScheck & Manual J accepted statewide. | 2018 Kentucky Residential Code (2012/2015 IECC) | 4A | R-49 | R-20 or R-13+5ci | 0.32 | 0.40 | 10°F / 91°F | Order → |
| Louisiana (LA) REScheck-Web v4.2.0 includes official 2021 Louisiana Energy Code. | 2021 Louisiana Residential Building Energy Code | 2A, 3A | R-38 | R-13 | 0.40 | 0.25 | 30°F / 94°F | Order → |
| Maine (ME) MUBEC requires 2021 IECC compliance via REScheck. | 2021 IECC (Maine MUBEC) | 6A, 7 | R-60 | R-20+5ci | 0.30 | 0.40 | -6°F / 84°F | Order → |
| Maryland (MD) REScheck + Manual J/S required across MD counties. | 2021 IECC (Maryland Building Performance Standards) | 4A, 5A | R-60 | R-20+5ci or R-13+10ci | 0.30 | 0.40 | 15°F / 91°F | Order → |
| Massachusetts (MA) REScheck-Web supports 2023 MA code for additions/alterations & non-HERS paths. | 2023 Massachusetts Stretch / 2021 IECC | 5A | R-60 | R-20+5ci | 0.30 | 0.40 | 7°F / 88°F | Order → |
| Michigan (MI) REScheck & Manual J accepted by all Michigan townships. | 2015 Michigan Uniform Energy Code (2015 IECC) | 5A, 6A, 7 | R-49 | R-20 or R-13+5ci | 0.32 | 0.40 | 4°F / 87°F | Order → |
| Minnesota (MN) REScheck & Manual J widely used for MN residential permits. | 2020 Minnesota Residential Energy Code (2018 IECC base) | 6A, 7 | R-49 | R-20+5ci | 0.30 | 0.40 | -14°F / 88°F | Order → |
| Mississippi (MS) REScheck & Manual J accepted statewide. | 2018 IECC (Adopted Locally) | 2A, 3A | R-38 | R-20 or R-13+5ci | 0.32 | 0.25 | 24°F / 94°F | Order → |
| Missouri (MO) St. Louis & Kansas City metros require REScheck & Manual J. | 2018 / 2021 IECC (Adopted by City/County) | 4A, 5A | R-49 | R-20 or R-13+5ci | 0.32 | 0.40 | 6°F / 94°F | Order → |
| Montana (MT) REScheck & Manual J accepted statewide. | 2021 IECC with Montana Amendments | 6B | R-49 | R-20+5ci | 0.30 | 0.40 | -15°F / 90°F | Order → |
| Nebraska (NE) Omaha & Lincoln require REScheck + Manual J. | 2018 IECC (Statewide Residential) | 5A | R-49 | R-20 or R-13+5ci | 0.30 | 0.40 | -3°F / 93°F | Order → |
| Nevada (NV) Clark County (Las Vegas) & Washoe (Reno) accept REScheck & Manual J. | 2021 IECC (Southern & Northern NV Amendments) | 3B, 4B, 5B | R-49 | R-20 or R-13+5ci | 0.30 | 0.25 | 28°F / 106°F | Order → |
| New Hampshire (NH) REScheck required for NH state energy code compliance. | 2018 IECC with NH Amendments | 5A, 6A | R-49 | R-20+5ci | 0.30 | 0.40 | -3°F / 87°F | Order → |
| New Jersey (NJ) NJ UCC requires REScheck + Manual J/S for residential permits. | 2021 IECC (NJ Uniform Construction Code) | 4A, 5A | R-60 | R-20+5ci | 0.30 | 0.40 | 13°F / 90°F | Order → |
| New Mexico (NM) REScheck & Manual J required statewide. | 2021 New Mexico Energy Conservation Code | 3B, 4B, 5B | R-49 | R-20 or R-13+5ci | 0.30 | 0.40 | 16°F / 94°F | Order → |
| New York (NY) REScheck-Web includes dedicated NYC profile & 2018/2021 IECC for NYS. | 2020 ECCCNYS (2018 IECC base) / NYC Energy Code | 4A, 5A, 6A | R-49 | R-20 or R-13+5ci | 0.30 | 0.40 | 6°F / 87°F | Order → |
| North Carolina (NC) Raleigh, Charlotte & all NC counties accept REScheck + Manual J. | 2018 NC Energy Conservation Code (with 2024 updates) | 3A, 4A, 5A | R-38 | R-15 or R-13+2.5ci | 0.32 | 0.25 | 20°F / 92°F | Order → |
| North Dakota (ND) REScheck & Manual J accepted statewide. | 2018 IECC with ND Amendments | 6A, 7 | R-49 | R-20+5ci | 0.30 | 0.40 | -19°F / 89°F | Order → |
| Ohio (OH) REScheck & Manual J accepted across Columbus, Cleveland, Cincinnati & statewide. | 2019 Residential Code of Ohio (2018 IECC base) | 4A, 5A | R-49 | R-20 or R-13+5ci | 0.30 | 0.40 | 5°F / 89°F | Order → |
| Oklahoma (OK) OKC & Tulsa require REScheck & Manual J. | 2015 / 2018 IECC (Oklahoma Uniform Building Code) | 3A, 4A | R-38 | R-20 or R-13+5ci | 0.32 | 0.25 | 14°F / 98°F | Order → |
| Oregon (OR) Manual J required for HVAC sizing; REScheck supported for UA verification. | Oregon Residential Specialty Code (ORSC) / 2021 IECC | 4C, 5B | R-49 | R-21 | 0.27 | 0.40 | 23°F / 89°F | Order → |
| Pennsylvania (PA) PA UCC third-party code agencies require REScheck + Manual J. | 2018 IECC (PA Uniform Construction Code) | 4A, 5A, 6A | R-49 | R-20 or R-13+5ci | 0.30 | 0.40 | 9°F / 89°F | Order → |
| Rhode Island (RI) REScheck & Manual J accepted statewide. | 2021 / 2024 IECC (RI State Building Code) | 5A | R-60 | R-20+5ci | 0.30 | 0.40 | 9°F / 86°F | Order → |
| South Carolina (SC) Charleston, Greenville & Columbia require REScheck + Manual J/S. | 2009 / 2018 SC Energy Standard | 3A | R-38 | R-13 or R-20 | 0.35 | 0.25 | 24°F / 94°F | Order → |
| South Dakota (SD) Sioux Falls & Rapid City accept REScheck & Manual J. | 2018 / 2021 IECC (Adopted by Municipality) | 5A, 6A | R-49 | R-20+5ci | 0.30 | 0.40 | -11°F / 91°F | Order → |
| Tennessee (TN) Nashville, Knoxville, Chattanooga & Memphis accept REScheck + Manual J. | 2018 IECC with Tennessee Amendments | 3A, 4A | R-49 | R-20 or R-13+5ci | 0.32 | 0.40 | 16°F / 93°F | Order → |
| Texas (TX) REScheck + Manual J + S accepted across Austin, DFW, Houston, San Antonio & statewide. | 2018 / 2021 IECC (Statewide Minimum 2015/2018; Austin/Dallas/Houston 2021) | 2A, 2B, 3A, 3B, 4B | R-38 | R-20 or R-13+5ci | 0.35 | 0.25 | 26°F / 99°F | Order → |
| Utah (UT) REScheck + Manual J required along Wasatch Front and statewide. | 2021 IECC with Utah Amendments | 3B, 5B, 6B | R-49 | R-20 or R-13+5ci | 0.30 | 0.40 | 9°F / 96°F | Order → |
| Vermont (VT) REScheck-Web 4.2.0 officially supports 2024 VT RBES. | 2024 Vermont RBES (Supported in REScheck-Web 4.2.0) | 6A | R-60 | R-20+5ci | 0.28 | 0.40 | -9°F / 85°F | Order → |
| Virginia (VA) Fairfax, Loudoun, Richmond & Tidewater require REScheck + Manual J/S. | 2021 Virginia Energy Conservation Code (2021 IECC) | 3A, 4A, 5A | R-49 | R-20 or R-13+5ci | 0.30 | 0.40 | 18°F / 92°F | Order → |
| Washington (WA) Manual J required for heat pump sizing; UA envelope reports supported. | 2021 Washington State Energy Code (WSEC-R) | 4C, 5B | R-49 | R-21 | 0.30 | 0.40 | 24°F / 86°F | Order → |
| West Virginia (WV) REScheck & Manual J accepted statewide. | 2015 IECC (WV State Building Code) | 4A, 5A | R-49 | R-20 or R-13+5ci | 0.35 | 0.40 | 10°F / 89°F | Order → |
| Wisconsin (WI) REScheck & Manual J accepted for Wisconsin residential permits. | Wisconsin UDC (SPS 322 Energy Conservation) | 6A, 7 | R-49 | R-20 or R-19+5ci | 0.30 | 0.40 | -7°F / 88°F | Order → |
| Wyoming (WY) REScheck & Manual J accepted across Wyoming jurisdictions. | 2018 / 2021 IECC (Adopted Locally) | 6B, 7 | R-49 | R-20+5ci | 0.30 | 0.40 | -9°F / 88°F | Order → |