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Arizona REScheck Requirements (2026)

Key facts:

  • No Statewide Code — Home Rule by City/County

  • Climate Zones 2B–5B

  • 2018–2024 IECC Depending on Jurisdiction

  • 5 ACH50 Max in Zone 2, 3 ACH50 in Zones 3B–5B

 

Arizona has no statewide residential energy code — it's a home-rule state, so every city and county adopts and amends its own version of the IECC on its own timeline. Phoenix is on the 2024 IECC (effective August 1, 2025), Scottsdale is on the 2021 IECC, Mesa adopted the 2024 ICC code family effective January 8, 2026, and Pima County/Tucson moved to the 2024 IECC under Ordinance 2026-6. REScheck is accepted where a jurisdiction requires energy-code compliance documentation — Scottsdale's own permit checklist names it directly — but always confirm the specific edition and requirement with the jurisdiction issuing your permit before you run the report.

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Arizona jurisdictions require REScheck documentation for residential permit applications under whichever IECC edition that specific city or county has adopted — and unlike most states, there's no single statewide code year to look up. Requirements vary by municipality, climate zone, and project type, so the same house built in Scottsdale versus Phoenix can face two different prescriptive ceiling R-value targets even though both cities sit in the same climate zone.

 

Arizona's Home-Rule Energy Code Landscape

Arizona is a home-rule state — there's no mandatory statewide residential energy code, and the U.S. Department of Energy lists Arizona's code status as "Applicable by County or Jurisdiction" rather than a fixed statewide edition. Each city and county adopts, amends, and updates its own version of the IECC independently, on its own schedule. That means the correct code edition for a project depends entirely on which building department is issuing the permit.

Jurisdiction  ·  Current Edition  ·  Effective Date

  • Phoenix:  2024 IECC (Ordinance G-7397)   —   August 1, 2025

  • Scottsdale:  2021 IECC, with local amendments   —   In effect (2021 cycle)

  • Mesa:  2024 ICC code family (includes IECC)   —   January 8, 2026

  • Pima County / Tucson:  2024 IECC (Ordinance 2026-6)   —   2026 (confirm exact date with Tucson-Pima Joint Code Committee)

  • Unincorporated Maricopa County:  2018 IECC — adopted but voluntary, not mandatory   —   N/A — not enforced

 

⚠ Arizona has no central registry of which edition every city or county is enforcing, and adoption dates keep moving — Tucson's 2024 IECC rollout alone shifted at least once. Always confirm the current edition and effective date directly with the building department issuing your permit before running REScheck or submitting a compliance path.

 

Arizona Climate Zones

Arizona spans four IECC climate zones because of its elevation range, from the low desert floor to the high country around Flagstaff. Climate zone assignment is county-based and doesn't change with code edition — only the numeric requirements tied to each zone change when a jurisdiction updates editions.

Zone  ·  Counties  ·  Profile

  • 2B:  Maricopa, Pima, Pinal, La Paz, Yuma   —   Hot-Dry — covers Phoenix, Tucson, Mesa, and the large majority of the state's population

  • 3B:  Mohave, Cochise, Graham, Greenlee, Santa Cruz   —   Warm-Dry

  • 4B:  Gila, Yavapai   —   Mixed-Dry — includes the Prescott area

  • 5B:  Apache, Coconino, Navajo   —   Cold-Dry — includes Flagstaff and the high country

 

Blower Door and Air Leakage Requirements

Arizona's air-leakage limit depends on which climate zone the project sits in, not which city — this split has held constant since the IECC first introduced mandatory blower door testing and still applies under the 2018, 2021, and 2024 editions. Zone 2B — which covers Phoenix, Tucson, Mesa, and nearly all of Arizona's population — gets the more lenient limit. Zone 3B and colder get the tighter one.

Climate Zone  ·  Max Air Leakage (ACH50)

  • 2B (Maricopa, Pima, Pinal, La Paz, Yuma):  5 ACH50

  • 3B–5B (Mohave, Cochise, Graham, Greenlee, Santa Cruz, Gila, Yavapai, Apache, Coconino, Navajo):  3 ACH50

 

Testing is done per RESNET/ICC 380, ASTM E779, or ASTM E1827, same as every other IECC state — there's no visual-inspection alternative once a jurisdiction has adopted a code cycle that mandates testing.

 

Prescriptive Insulation Requirements by Climate Zone

This is the one place where Arizona's home-rule setup actually changes the numbers you're targeting, not just the paperwork. The 2021 IECC bumped ceiling insulation up one full tier nationwide — R-38 became R-49, R-49 became R-60 — and the 2024 IECC reverted ceilings back to the pre-2021 levels. Wall and floor requirements didn't move between cycles. So a Scottsdale project (2021 IECC) and a Phoenix project (2024 IECC) in the exact same climate zone target different ceiling R-values, even though every other component matches.

Zone  ·  Wood Frame Wall  ·  Floor  ·  Ceiling (2018 & 2024 IECC)  ·  Ceiling (2021 IECC only)

  • 2B:  R-13, or R-0+10 continuous   —   R-13   —   R-38   —   R-49

  • 3B:  R-20, or R-13+5ci, or R-0+15ci   —   R-19   —   R-38   —   R-49

  • 4B:  R-30, or R-20+5ci, or R-13+10ci, or R-0+20ci   —   R-19   —   R-49   —   R-60

 

Fenestration: U-factor 0.40 max in Zone 2B, 0.35 max in Zone 3B and 4B. SHGC 0.25 max in Zones 2B and 3B (Zone 4B and colder have no SHGC requirement). Confirm your specific project's edition before finalizing window schedules — a 2021-cycle jurisdiction and a 2024-cycle jurisdiction in the same zone will both accept these fenestration numbers, since only ceiling insulation shifted between cycles.

 

Is REScheck Accepted in Arizona?

Yes, where the jurisdiction requires energy-code compliance documentation — but acceptance is jurisdiction-by-jurisdiction, not a single statewide yes. Scottsdale's own single-family submittal checklist lists "1 copy ResCheck energy code compliance" as a required document. Phoenix's 2024 IECC amendments define three compliance paths — Prescriptive, Performance, and the Total UA Alternative under R402.1.4 — and REScheck is the standard software nationwide for running that Total UA calculation, though Phoenix's own amendment document doesn't brand-name REScheck specifically, so it's worth a quick confirmation call to Phoenix Planning & Development (602-262-7811) before you submit.

 

⚠ Unincorporated Maricopa County adopted the 2018 IECC but labeled it voluntary rather than mandatory — meaning REScheck acceptance there is genuinely uncertain and depends on what the reviewing office decides to require. Don't assume; confirm with that specific office first.

 

Common Arizona Permit Requirements

  • Manual J load calculations

  • Manual S equipment sizing

  • Window and door schedules with U-factor/SHGC labels

  • Duct leakage testing

  • Blower door testing (5 ACH50 in Zone 2B, 3 ACH50 in Zones 3B–5B)

  • Insulation specifications by assembly

  • REScheck or equivalent Total UA documentation, where required

 

Common REScheck Failure Reasons in Arizona

Most Common Errors

  • Wrong climate zone selected — Arizona spans four zones (2B–5B), and defaulting to "desert Southwest" without checking the actual county is a frequent mistake

  • Ceiling R-value pulled from the wrong code cycle (R-38 vs. R-49 in Zone 2B/3B, R-49 vs. R-60 in Zone 4B)

  • Missing or incorrect SHGC entry in Zones 2B and 3B

  • Window U-factor entered above the 0.40/0.35 ceiling for the zone

 

Mechanical and Envelope Issues

  • Duct leakage testing omitted or submitted late

  • Blower door result submitted against the wrong ACH50 threshold for the zone

  • Incorrect wall assembly R-value when using a continuous-insulation combination instead of cavity-only

 

Major Cities and Jurisdictions in Arizona

Phoenix

2024 IECC, effective August 1, 2025, under Ordinance G-7397. Zone 2B. Three compliance paths: Prescriptive, Performance, and Total UA Alternative.

 

Tucson / Pima County

2024 IECC under Ordinance 2026-6. Zone 2B. Adopted through the Tucson-Pima County Joint Code Committee process — confirm the current effective date with that committee, since Tucson's 2024 rollout has already shifted once.

 

Scottsdale

2021 IECC with local amendments. Zone 2B. REScheck explicitly required on single-family submittal checklists.

 

Mesa

Adopted the 2024 ICC code family (which includes the IECC), effective January 8, 2026, for permit applications submitted on or after that date. Zone 2B.

 

Flagstaff and Northern Arizona

Zone 5B — the coldest zone in the state, covering Coconino, Navajo, and Apache counties. Higher insulation and tighter air-sealing targets than the rest of Arizona, plus its own local adoption timeline separate from the Phoenix/Tucson metro cities.

 

Yuma and La Paz County

Zone 2B, same ACH50 and SHGC targets as Phoenix and Tucson. Confirm the locally adopted edition directly — this area isn't covered by the major-city ordinances listed above.

 

Frequently Asked Questions About REScheck in Arizona

Does Arizona have one statewide energy code?

No. Arizona is a home-rule state with no mandatory statewide residential energy code. Every city and county adopts and amends its own IECC edition independently, so the correct code year depends entirely on where the project is permitted.

 

What IECC edition does Phoenix use?

The 2024 IECC, effective August 1, 2025, under Ordinance G-7397.

 

What IECC edition does Scottsdale use?

The 2021 IECC with local amendments — one cycle behind Phoenix, which matters because ceiling R-value targets differ between the two editions in the same climate zone.

 

Why does the required ceiling R-value change between cities in the same climate zone?

Because the code edition changed the number, not the climate. The 2021 IECC raised ceiling insulation one tier nationwide (R-38 to R-49, R-49 to R-60); the 2024 IECC reverted it back down. A 2021-cycle city like Scottsdale and a 2024-cycle city like Phoenix will target different ceiling R-values in the exact same zone.

 

What climate zones does Arizona have?

Four: Zone 2B (Maricopa, Pima, Pinal, La Paz, Yuma — Phoenix and Tucson metro), Zone 3B (Mohave, Cochise, Graham, Greenlee, Santa Cruz), Zone 4B (Gila, Yavapai), and Zone 5B (Apache, Coconino, Navajo — the Flagstaff/high-country area).

 

What is Arizona's blower door requirement?

5 ACH50 maximum in Zone 2B (Phoenix, Tucson, Mesa, and most of the state's population), 3 ACH50 maximum in Zones 3B through 5B. Testing is required per RESNET/ICC 380, ASTM E779, or ASTM E1827 wherever a jurisdiction's adopted code cycle mandates it.

 

Is REScheck accepted in Arizona?

Yes, where the local jurisdiction requires energy-code compliance documentation. Scottsdale names REScheck directly on its permit checklist. Phoenix accepts the Total UA Alternative path that REScheck performs. Coverage is jurisdiction-specific rather than a single statewide yes — confirm with the issuing building department.

 

Is REScheck required in unincorporated Maricopa County?

Uncertain — unincorporated Maricopa County adopted the 2018 IECC but labeled it voluntary rather than mandatory, so whether REScheck (or any energy-code documentation) is required depends on the reviewing office's current practice. Confirm directly before assuming.

 

Are barndominiums and ADUs required to comply?

Yes, wherever the local jurisdiction has adopted an enforceable energy code — conditioned accessory dwelling units and barndominiums are treated as residential construction subject to that jurisdiction's current IECC edition.

 

Is Manual J required alongside REScheck in Arizona?

Wherever a jurisdiction has adopted an IRC edition, Section M1401.3 requires HVAC equipment sizing per Manual S based on a Manual J load calculation — independent of which IECC edition applies for envelope compliance. Given Arizona's cooling-dominated climate, most building departments expect to see it regardless of which specific energy-code cycle is in effect.

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