Arizona Building Code Editions by City: A Phoenix-Metro Comparison

The exact code edition your home is built to depends entirely on which side of a jurisdiction line your lot sits, because the state leaves code adoption to each city and county rather than setting one rule for everyone. The code authors at the authority having jurisdiction (AHJ) put it plainly: codes are adopted locally in Arizona and are predominantly the International Codes (I-codes). In the Phoenix metro that produces a striking spread of nearly a decade, from the 2024 codes in Phoenix down to the 2015 codes still in force in Paradise Valley. This page lines up the ten jurisdictions Jematell Homes builds in so you can see the differences at a glance, then explains why they exist and what they cost you.

The comparison table

The "edition" column is the residential and building code cycle (IRC and IBC). The "NEC" column is the electrical code, which often runs a cycle behind the I-codes because the National Electrical Code publishes on a different schedule. Every edition listed below is confirmed against each jurisdiction's own published adoption.

Two extra notes belong with the table. Cave Creek keeps the 2018 residential energy code for houses even though it moved to the 2024 codes for everything else, so a single-family build there follows a lighter energy path than the 2024 cycle would suggest. Maricopa County adopts the 2018 energy code as voluntary, not mandatory, so a rural county build is not forced into the energy paperwork a city requires. Those two wrinkles change what a homeowner actually pays for insulation and duct testing, so they are worth catching early.

Why the editions differ

The reason is structural, not an oversight. The I-codes are written by the International Code Council on a three-year cycle (2018, 2021, 2024), but adoption is a local political act. A city council or board of supervisors has to vote to adopt the new cycle, edit it for local desert conditions, and set an effective date. The code authors confirm this:

Codes are adopted locally in Arizona and are predominantly the I-codes.

Some jurisdictions move fast and some move slowly. Phoenix and Fountain Hills jumped to the brand-new 2024 cycle in 2025. Cave Creek followed on January 1, 2026. Scottsdale sits a cycle back on 2021. Maricopa County, Carefree, Casa Grande, and Apache Junction are all still on 2018. A town that updates every cycle stays current; a town that updates every second or third cycle falls a few years behind by design. None of them are out of compliance, because there is no state floor forcing a single edition. The local AHJ has the final word, and its adopted edition is the law inside its lines.

The electrical code drifts its own way. The NEC is on a three-year cycle too (2017, 2020, 2023), but a jurisdiction often adopts a slightly older NEC than its I-codes because the books pair up by what was current at adoption time. That is why Phoenix runs the 2024 I-codes with the 2023 NEC, and Scottsdale runs the 2021 I-codes with the 2020 NEC.

What it means for a builder or homeowner

The edition gap is not academic. It changes framing details, wiring rules, and energy specs, and those changes hit your plans and your budget.

• A plan set is not portable across the line. A custom-home plan drawn to Phoenix's 2024 codes is not automatically correct for a lot in Carefree or Casa Grande on the 2018 codes, and the reverse is also true. Plan reviewers check against the edition their jurisdiction adopted, so a reused set from the wrong city is the most common and most expensive plan-review correction.
• Energy paperwork varies the most. Phoenix and Fountain Hills enforce the 2024 energy code, Scottsdale the 2021, and Cave Creek keeps the 2018 energy code for houses. Maricopa County treats energy as voluntary. The insulation R-values, duct-leakage testing, and window U-factors you have to prove change with that edition, and so does the cost.
• Electrical follows a different book per city. An electrician quoting a Phoenix job works from the 2023 NEC. The same electrician on a Maricopa County lot a few miles away works from the 2017 NEC, two cycles back. Arc-fault and ground-fault protection requirements differ between them.
• Effective dates create transition windows. Edition is tied to when your permit was issued, not today's calendar. A permit pulled in Phoenix before August 1, 2025 may still run under the prior 2018 code. A Fountain Hills application received before September 1, 2025 may still run under the prior cycle. If your project straddles an effective date, confirm which edition applies before your designer finalizes the set.

For example, say you own two lots, one in Phoenix and one in Casa Grande, and you want the same floor plan on both. You cannot submit one identical set to both offices. The Phoenix reviewer checks the energy sheet against the 2024 IECC and the wiring against the 2023 NEC. The Casa Grande reviewer checks the same home against the 2018 IECC and the 2017 NEC. The framing, the duct sealing, and the panel can all come back with different corrections. Each lot needs its plans confirmed to its own jurisdiction's edition before a permit issues.

How this connects to the rest of the module

This hub is the map; each spoke has the full detail. For the exact code list, amendments, and effective dates in your jurisdiction, see the per-city entries: Scottsdale , Phoenix , Maricopa County , Cave Creek , Fountain Hills , Carefree , Casa Grande , and Apache Junction . For the bigger picture of where code sits in the build, see the steps to building a custom home in Arizona and what building codes apply in Scottsdale .

Source

Arizona's local-adoption structure is tracked by the code authors at ICC Code Adoptions for Arizona . Each edition above is confirmed against the jurisdiction's own published adoption, including the City of Scottsdale Building Code Information and the City of Phoenix Building Construction Codes . The remaining cities and towns each publish their own adoption, linked from the per-city entries above.

This page is general information, not a code interpretation. Editions and effective dates change on each jurisdiction's own schedule, so confirm the current adopted code with the local building department before you rely on a specific edition.