Mesa allows one attached and one detached ADU by right on any lot where a single residence is allowed — including commercial, mixed-use, and downtown districts — under Ordinance 5883 (adopted October 7, 2024) implementing Arizona HB 2720. There is no minimum lot size, no additional parking requirement, and garage conversions are exempt from replacing covered parking. ADUs are capped at 75% of the primary home's interior habitable area or 1,000 sq ft, whichever is less.
Zoning & Size Requirements [1][2][3][4]
| Allowed Zones | All districts where a single residence is allowed (Agricultural, Residential, Commercial & Mixed-Use, Downtown); any lot with an existing single residence qualifies regardless of district (MZO 11-31-3) |
| Max Size (Detached) | 75% of primary residence's interior habitable area or 1,000 sq ft, whichever is less |
| Max Size (Attached) | 75% of primary residence's interior habitable area or 1,000 sq ft, whichever is less |
| Max Size (JADU) | Not a defined category in Mesa; internal/attached ADUs follow standard ADU rules |
| Max Height | Same as primary residence height limit for the underlying zoning district |
| Max Units | 1 attached + 1 detached per lot; a 3rd detached ADU allowed on lots of 1+ acre if at least one ADU is income-restricted affordable (80% AMI) |
Setback Requirements [1][2][3][4]
| Rear Setback | 5 feet minimum for new structures; existing-structure conversions require no additional setback |
| Side Setback | 5 feet minimum for new structures |
| Front Setback | Same as primary residence front and street-side setbacks for the underlying district |
| Parking Required | No additional parking required; garage/carport conversions need not replace covered parking elsewhere (Ord. 5883) |
| Owner Occupancy | Not required |
| Min Lot Size | None — Mesa imposes no minimum lot size for ADUs |
Permit Process & Fees [5][6]
| Approval Process | Zoning verification/pre-application, ADU site plan submittal, then standard building permit through Mesa Development Services (no use permit required) |
| Review Timeline | Residential plan review commonly runs days-to-weeks per third-party permit data (3-18 business days cited); confirm current turnaround on Mesa's Building Permits Dashboard |
| Permit Fees | Valuation-based per Mesa's Schedule of Fees & Charges; no flat ADU fee published — confirm with Mesa Development Services |
| Impact Fees | Development impact fees apply per Mesa City Code Title 5, Chapter 17; amount varies by location and unit size — confirm with Mesa Development Services |
| Plan Check | Confirm with Mesa Development Services (city publishes live review times on its Building Permits Dashboard) |
| Pre-Approved Plans | No city pre-approved ADU plan program identified as of June 2026 — confirm with Mesa Development Services |
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Construction Costs [7][8]
| Average Build Cost | $120,000-$240,000 |
| Cost per Sq Ft | $135-$270 |
| Garage Conversion | $60,000-$140,000 |
| Prefab ADU (Installed) | $85,000-$200,000 |
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Rental Income Potential [9]
| Avg Rent (1 Bedroom) | $1,150-$1,450/mo |
| Avg Rent (2 Bedroom) | $1,400-$1,800/mo |
| Short-Term Rental | Ordinance 5883 does not address short-term rental of ADUs; Arizona law protects separate LONG-term leasing — confirm STR licensing rules with Mesa Planning |
| Est. Annual ROI | 6-9% annual return |
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Recent Law Changes
What's Changed Recently
- Mesa Ordinance 5883 (adopted October 7, 2024, effective 30 days later): repealed and replaced MZO Section 11-31-3, allowing ADUs on any lot with a single residence, raising the size cap from 30% to 75%/1,000 sq ft, setting 5-ft rear/side setbacks, and waiving covered-parking replacement for garage conversions
- Arizona HB 2720 (signed May 21, 2024; ARS 9-461.18): required cities over 75,000 population to allow 1 attached + 1 detached ADU by right by January 1, 2025, and bars owner-occupancy requirements, extra parking, and design-matching mandates
- Arizona HB 2928 (signed May 2025): extended similar ADU mandates to large counties
Tips for Building an ADU in Mesa
- Mesa is one of the few Valley cities allowing ADUs in commercial, mixed-use, and downtown districts — any lot with an existing single residence qualifies regardless of zoning
- Garage conversions are the cheapest path in Mesa: Ordinance 5883 waives the usual requirement to rebuild covered parking elsewhere on the lot
- Small-lot RSL districts were excluded from ADUs before October 2024 — if you were previously turned away, your lot likely qualifies now (no minimum lot size)
- Mesa requires the ADU to share the primary home's water, sewer, and electric meters — budget for electrical panel capacity rather than a separate service drop, and check for public utility easements before siting a detached unit
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Mesa Ordinance No. 5883 — Accessory Dwelling Units (MZO 11-31-3, full text) Municipal Code — Accessed 2026-06-10
- Mesa City Council Report — MZO Text Amendment (ADUs), Sept 23, 2024 Planning Department — Accessed 2026-06-10
- Accessory Dwelling Units (ADUs) — City of Mesa Planning Department — Accessed 2026-06-10
- Arizona HB 2720 Bill Summary (ARS 9-461.18) — Arizona Legislature state_law — Accessed 2026-06-10
- Building Permit & Plan Review — City of Mesa Planning Department — Accessed 2026-06-10
- Mesa City Code Title 5 Ch. 17 — Development Impact Fees Municipal Code — Accessed 2026-06-10
- HomeAdvisor — ADU Construction Cost Data Market Data — Accessed 2026-06-10
- Angi — Guest House / ADU Build Costs Market Data — Accessed 2026-06-10
- RentCafe — Average Rent in Mesa, AZ (May 2026: 1BR $1,294, 2BR $1,594) Market Data — Accessed 2026-06-10
Frequently Asked Questions
Can I build an ADU in Mesa?
Yes. ADUs are allowed in All districts where a single residence is allowed (Agricultural, Residential, Commercial & Mixed-Use, Downtown); any lot with an existing single residence qualifies regardless of district (MZO 11-31-3) in Mesa. The maximum size for a detached ADU is 75% of primary residence's interior habitable area or 1,000 sq ft, whichever is less. No owner-occupancy is required.
How much does an ADU cost in Mesa?
ADU construction in Mesa typically costs $120,000-$240,000. Garage conversions run $60,000-$140,000, and prefab ADUs cost $85,000-$200,000.
How much can I rent an ADU for in Mesa?
Average ADU rents in Mesa are $1,150-$1,450/mo for a 1-bedroom and $1,400-$1,800/mo for a 2-bedroom unit.
Do I need parking for an ADU in Mesa?
No additional parking required; garage/carport conversions need not replace covered parking elsewhere (Ord. 5883). Check with Mesa planning department for the latest Arizona ADU parking rules, as many states have relaxed requirements in recent years.
How long does it take to get an ADU permit in Mesa?
The permit review timeline in Mesa is Residential plan review commonly runs days-to-weeks per third-party permit data (3-18 business days cited); confirm current turnaround on Mesa's Building Permits Dashboard. Fees range from Valuation-based per Mesa's Schedule of Fees & Charges; no flat ADU fee published — confirm with Mesa Development Services.
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