Maricopa County, AZ Accessory Structures: ADU Rules (2026)
ADU rules in Maricopa County, AZ, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Permit type
- By-right, no hearing or variance
- Units allowed
- 1 attached + 1 detached ADU
- Size cap (under 1 acre)
- 75% of home or 1,000 sq ft
- Detached ADU setback
- 5 feet from side/rear lot lines
- Detached ADU height limit
- 18 feet in required yard
Summary
Unincorporated Maricopa County allows one attached and one detached accessory dwelling unit by right on any single-family lot: no public hearing, variance, or special permit required under the zoning ordinance.
In accordance with Arizona State Statute, ADUs are a permitted use on any lot or parcel zoned for single-family residential use. A public hearing, variance, or special permit shall not be required. ... At least one attached and one detached ADU shall be permitted on each lot or parcel where a single-family dwelling is allowed.
Full Breakdown
The Maricopa County Zoning Ordinance treats ADUs as a permitted use on any single-family-zoned lot in unincorporated areas: at least one attached and one detached ADU is allowed per lot, with a second detached unit permitted on parcels one acre or larger if deed-restricted as affordable housing. No ADU may exceed the size of the principal dwelling, and on lots under one acre an ADU is capped at 75% of the primary home's size or 1,000 square feet, whichever is smaller. Detached ADUs must sit at least 5 feet from side or rear lot lines and are limited to 18 feet in height within those setbacks, and only one ADU per parcel may be used as a short-term rental.
Violations & Fines
Building or maintaining an ADU that violates the ordinance's size, setback, or height standards is a class 2 misdemeanor, with each day of continued violation a separate offense; the county can instead pursue civil penalties under A.R.S. § 11-815(D).
Frequently Asked Questions
Do I need a public hearing or variance to build an ADU in unincorporated Maricopa County?
How big can an ADU be on a lot under one acre?
Can I rent out my ADU as a short-term rental?
Sources & Official References
Other rules in Maricopa County
How Maricopa County compares: Easiest Cities to Build an ADU·Compare Maricopa County to another location·View the Arizona accessory structures overview
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