ADU Rules in Mesa, AZ (2026)
ADU rules, permit requirements, size limits, and fees for Mesa, AZ. Source-cited from official municipal code.
Yes, ADUs are allowed in Mesa, AZ.
Mesa, AZ permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law governs the approval process. In Mesa, the local building department handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Mesa.
ADU Size Limits
ADU Size Limits in Mesa: Detached ADU: up to 75% of the Primary Residence's interior Habitable Area, or 1,000 square feet, whichever is less (max height: The height of an attached or detached ADU shall comply with the primary residence height requirements for the underlying zoning district.). Attached ADU: 75% of the Primary Residence's interior Habitable Area, or 1,000 square feet, whichever is less. Arizona does not use California's JADU concept. Mesa Zoning Ordinance limits ADU to 50% of primary dwelling or 1,200 sqft. Mesa's RS-6 lots (6,000 sqft typical) with 1,500-2,000 sqft primary homes can support 750-1,000 sqft ADUs — a practical size for rental income in the Phoenix suburbs.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 75% of the Primary Residence's interior Habitable Area, or 1,000 square feet, whichever is less · Verified May 20, 2026 · Source | The height of an attached or detached ADU shall comply with the primary residence height requirements for the underlying zoning district. · Verified July 14, 2026 · Source |
| Attached ADU | 75% of the Primary Residence's interior Habitable Area, or 1,000 square feet, whichever is less · Verified May 20, 2026 · Source | The height of an attached or detached ADU shall comply with the primary residence height requirements for the underlying zoning district. · Verified July 14, 2026 · Source |
Permit Fees
ADU Permit Fees in Mesa: Plan check fee: Varies. Building permit fee: Varies. Impact fees: None. School fees: None or N/A. Total estimated permit cost: Varies.
| Fee Type | Amount |
|---|---|
| Plan Check | $250–$1,400 |
| Building Permit | Based on construction value — typically $800–$3,500 |
| Impact Fees | Mesa water, sewer, and transportation development fees apply — typically $3,000–$7,000 |
| School Fees | None |
| Total Estimate | See official source |
Permit Timeline
Mesa ADU Permit Timeline: Permit timeline has not been confirmed — contact the department for current processing times. Apply through the local building department online permit portal. Contact them through their official website for current contact information.
Setback Requirements
ADU Setback Requirements in Mesa: Front setback: Front and secondary front (street side) setbacks shall comply with the primary residence setback requirements for the underlying zoning district.. Side setback: 5 feet. Rear setback: 5 feet. Per Arizona HB 2720 (ARS §9-461.18(B)(6)), municipalities cannot require rear or side setbacks greater than 5 feet for ADUs. Mesa Zoning Ordinance was updated to reflect 5-foot maximum. Front setback follows primary dwelling line per zone standard. RS-6 zones typically require 20-25 ft front setbacks.
Parking Requirements
Parking Requirements: No additional parking spaces are required for an ADU. If a garage or carport is converted to an ADU, covered parking for the primary residence is not required to be replaced elsewhere on the lot or parcel.
Restrictions & Requirements
- ADU must be on same lot as primary single-family dwelling
- Maximum size: 50% of primary dwelling or 1,200 sqft per Mesa Zoning Ordinance
- One ADU per single-family lot
- Lot coverage limits apply per zone
- ADU must meet Mesa building code and zoning standards
- Corner lots may have additional setback requirements
How Many ADUs Are Allowed?
Number of ADUs Allowed in Mesa: Single-family lots: One (1) attached ADU and one (1) detached ADU are permitted per lot or parcel in any zoning district where a Single Residence is allowed. Multifamily properties: not confirmed — see official source.
- Single-Family Lots
- One (1) attached ADU and one (1) detached ADU are permitted per lot or parcel in any zoning district where a Single Residence is allowed · Verified July 14, 2026 · Source
- Multifamily Properties
- ADUs permitted in RM zones per Mesa Zoning Ordinance — consult Mesa Planning for zone-specific standards
Statewide Preemption
ADU Preemption
Arizona state law preempts local ADU rules — local governments cannot impose stricter standards.
View Arizona preemption detailsFrequently Asked Questions
Can I build an ADU in Mesa?
Yes. Mesa, AZ allows accessory dwelling units. On a single-family lot you can build One (1) attached ADU and one (1) detached ADU are permitted per lot or parcel in any zoning district where a Single Residence is allowed.
How big can an ADU be in Mesa?
The maximum size for a detached ADU in Mesa is 75% of the Primary Residence's interior Habitable Area, or 1,000 square feet, whichever is less square feet.
How long does it take to get an ADU permit in Mesa?
The typical ADU permit timeline in Mesa is Mesa Building Inspection Division processes ADU permits through Mesa's online portal. Standard ADU: 3-5 weeks plan review. Electronic plan submittals available. Construction typically 3-8 months.. Total estimated permit fees are $2,000–$9,000 total fees.
Do I need extra parking for an ADU in Mesa?
Mesa parking rules for ADUs: No additional parking spaces are required for an ADU. If a garage or carport is converted to an ADU, covered parking for the primary residence is not required to be replaced elsewhere on the lot or parcel.
Do I have to live on-site to have an ADU in Mesa?
Owner-occupancy requirement in Mesa: No owner-occupancy requirement per Arizona HB 2720 (ARS §9-461.18(B)(2)). Mesa removed local owner-occupancy requirement in 2024.
Source: Mesa City Code Chapter 11, Section 11-3-3 — Accessory Dwelling Units; Arizona HB 2720 (Laws 2024). Last verified April 6, 2026. View source