Yes: Mesa allows one attached and one detached ADU by right on any lot where a single residence is allowed, including small-lot RSL, multiple-residence, downtown, mixed-use and commercial districts, under Mesa Zoning Ordinance Section 11-31-3 (Ordinance 5883, effective November 2024, refined by Ordinance 5950 in August 2025 and Ordinance 6025 in August 2026) implementing ARS 9-461.18. The unit's interior habitable area is capped at 75% of the house or 1,000 sq ft, whichever is less; side and rear setbacks are 5 ft, height follows the district limit for the house, and there is no minimum lot size, no added parking and no owner-occupancy rule. You need only a building permit through the DIMES portal: plan review is targeted at 10 working days, and the permit fee is about $1,250 on a $150,000 build, plus a possible $402 public-safety impact fee and $311 solid-waste fee. Phoenix-area builders quote $150,000-$280,000 for a mid-range detached casita and $80,000-$150,000 for a garage conversion.
In Mesa you will also hear an ADU called a casita — Arizona's ADU statute (A.R.S. §9-461.18) and most local codes use it. The rules on this page apply either way.
Outside city limits? If your property is in unincorporated Maricopa County (not within Mesa's boundaries), different rules apply — see our Maricopa County (unincorporated) ADU rules.
Zoning & Size Requirements [1][2][3][4][5][6][7][8]
Yes — Mesa allows ADUs. A detached ADU can typically be up to 1,000 sq ft under current Arizona and Mesa zoning rules.
See what this means for your lot — ask Mesa ADU builders for a quote →
| Allowed Zones | Any lot in a district where a single residence is allowed: Agricultural (AG), Single Residence (RS), Small Lot Single Residence (RSL), Multiple Residence (RM), Downtown Residence (DR), Mixed Use (MX) and the NC, LC and GC commercial districts; a lot in any other district qualifies if its principal use is an existing single residence (MZO 11-31-3(A), Ord. 6025). Historic Districts need a Certificate of Appropriateness (Ch. 74); ARS 9-461.18(G) excludes tribal land and airport-noise areas. |
| Max Size (Detached) | 75% of the primary residence's interior habitable area or 1,000 sq ft, whichever is less (11-31-3(C)); a 1,200 sq ft house allows up to 900 sq ft, a house of 1,334 sq ft or more allows the full 1,000. Since Ord. 5950 (Aug 2025) the ADU no longer counts toward the cap on combined detached accessory floor area in 11-30-17(A)(4). District lot-coverage and building-coverage limits still apply (11-31-3(E)). |
| Max Size (Attached) | Same cap as detached: 75% of the primary residence's interior habitable area or 1,000 sq ft, whichever is less (11-31-3(C)). An attached ADU needs its own separate, independent entrance and, since Ord. 6025 (Aug 2026), may not have an internal connection to the main house; one kitchen (partial or full) per ADU (11-31-3(B)). |
| Max Size (JADU) | Mesa has no junior ADU category. A unit carved out of the existing house is simply an attached ADU: same 75%/1,000 sq ft cap, a separate outside entrance with no internal door to the house (Ord. 6025), no more than one kitchen, and no added setbacks for an internal renovation (11-31-3(B)-(D)). |
| Max Height | Same as the primary residence height limit for the underlying zoning district (11-31-3(F)); the city's ADU page confirms a two-story ADU is allowed wherever the district allows a two-story house. Unlike an ordinary detached accessory building over 15 ft (11-30-17(B)(2)(e)), an ADU keeps its 5-ft side and rear setbacks at any permitted height. |
| Max Units | One attached plus one detached ADU per lot (11-31-3(A)(1)-(2)). A second detached ADU (three total) is allowed on a lot of 1 acre or more if at least one ADU is rented to households at or below 80% of area median income under a deed restriction or development agreement (11-31-3(A)(3)). Manufactured homes, RVs and trailers cannot serve as ADUs (11-31-3(B)), and an ADU may not be used as a boarding house (Ord. 6025). |
Setback Requirements [1][2][3][4][5][6][7][8]
Mesa requires a rear setback of about 5 ft for a detached ADU, and no additional parking is required. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 5 ft minimum for a new attached or detached ADU (11-31-3(D)(1)(a), as rewritten by Ord. 5950, effective Aug 2025). An existing detached building that meets the 11-30-17 accessory-building setbacks, or is legal non-conforming, can be converted to an ADU with no added setback; an expansion may follow the existing non-conforming line if it does not worsen it. Since Ord. 6025 a detached ADU must also sit at least 5 ft from the house, other ADUs and accessory buildings. |
| Side Setback | 5 ft minimum on interior side lines for new construction, with the same conversion exceptions as the rear setback (11-31-3(D)); a corner-lot street side follows the primary residence's street-side setback for the district (D)(1)(b). Uninhabitable space attached to an ADU (garage, storage, workshop) follows the district setbacks for an attached ADU, or the 11-30-17 accessory-building setbacks for a detached ADU (Ord. 6025). |
| Front Setback | Same as the primary residence's front and secondary-front (street-side) setback for the underlying district (11-31-3(D)(1)(b)). An internal renovation of the house needs no new setbacks; a ground-floor addition for an ADU must meet the 5-ft side/rear rule, and a second-story addition must meet the house's own district setbacks (11-31-3(D)(3), Ord. 5950). |
| Parking Required | None. No additional parking spaces are required for an ADU, and a garage or carport converted to an ADU need not have its covered parking replaced elsewhere on the lot (11-31-3(G)); ARS 9-461.18(B)(3) bars parking requirements and in-lieu fees. The city's ADU page notes the primary residence must still keep its own two required spaces. |
| Owner Occupancy | Not required. Neither 11-31-3 nor state law requires the owner to live on site, and ARS 9-461.18(B)(2) bars any family, marital or employment relationship test between the house and ADU occupants. The ADU may be leased separately long-term (ARS 9-461.18(B)(1)) but may not be sold separately from the primary residence (city ADU page). |
| Min Lot Size | None. 11-31-3(B)(1): 'There are no minimum lot size requirements to establish an ADU.' The unit must still fit within the district's lot-coverage and building-coverage limits (11-31-3(E)), and a third ADU is possible only on lots of 1 acre or more. |
Permit Process & Fees [9][10][11][12][13][14][15]
An ADU permit in Mesa goes through a ministerial, by-right review. Typical timeline: Written plan-review comments or approval within 10 working days (Monday-Thursday, excluding holidays) per Mesa's Residential Construction page; an expedited 5-working-day review costs an extra 100% of the permit fee. Allow for at least one re-submittal cycle. Permit fees: Valuation-based (Development Services Schedule of Fees, July 2026): $500 plus $6 per $1,000 of valuation over $25,000, up to $200,000; then $1,550 plus $9 per $1,000. A $150,000 ADU pays about $1,250 and a $250,000 unit about $2,000, plan review and trade permits included.
| Approval Process | By-right building permit through Development Services' DIMES online portal (Accella); a code-compliant ADU needs no use permit, hearing or neighbor notice (ARS 9-461.18 'permitted use'). Submit a fully dimensioned site plan, code data sheet with scope of work, architectural and structural plans, and electrical, plumbing and mechanical plans (contractor licence verification form if a contractor pulls the permit); in a Historic District a Certificate of Appropriateness comes first. Inspections are booked online, by phone or text (Mon-Fri 6:30 am-5 pm); a permit is valid 180 days from issuance. Permit Services: PermitServices@mesaaz.gov, 480-644-4273, 55 N. Center St. |
| Review Timeline | Written plan-review comments or approval within 10 working days (Monday-Thursday, excluding holidays) per Mesa's Residential Construction page; an expedited 5-working-day review costs an extra 100% of the permit fee. Allow for at least one re-submittal cycle. |
| Permit Fees | Valuation-based (Development Services Schedule of Fees, July 2026): $500 plus $6 per $1,000 of valuation over $25,000, up to $200,000; then $1,550 plus $9 per $1,000. A $150,000 ADU pays about $1,250 and a $250,000 unit about $2,000, plan review and trade permits included. |
| Impact Fees | City Code Title 5 Ch. 17 lists a Public Safety impact fee of $402 per detached single-residence dwelling unit ($388 attached) on the schedule as of June 30, 2025, and Code 5-13-2 a Solid Waste Residential Development Fee of $311 per dwelling unit (July 2026 schedule). Water impact fees were replaced on January 1, 2026 by Water and Wastewater Capacity Fees (Code 8-10-13), charged only where a new or larger service connection is needed; because 11-31-3(H)(2) requires an ADU to share the house's meters, a standard ADU should not trigger them. Neither schedule has an ADU line, so confirm with Permit Services (480-644-4273) whether the public-safety and solid-waste fees are assessed on your unit before budgeting. |
| Plan Check | Full residential plan review within the 10-working-day target; a non-refundable $500 application deposit (valuations $25,000-$200,000) is credited to the permit fee. Fourth and later re-submittals before issuance cost $120 per staff hour (2-hour minimum) and post-permit addenda $120 per hour with a $120 deposit. Plans are checked against the 2024 IRC and companion codes with Mesa amendments and the 2023 NEC; state law bars a fire-sprinkler or commercial-code requirement for an ADU (ARS 9-461.18(D)). |
| Pre-Approved Plans | Mesa's Preapproved Housing Design Plan Program (per the city, under ARS 9-461.19; the plan classes match ARS 9-461.20) accepts Class 4 ADU plans of exactly 200, 600 or 1,000 sq ft, with no review fee and standard permit fees at issuance; users sign a plan agreement and may need site-specific sheets. As of September 2026 the program page lists the classes but posts no ADU plans to choose from, so email PermitServices@mesaaz.gov for what is available; state law required at least three ADU plans from July 1, 2026. |
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Construction Costs [16][17][18]
Building an ADU in Mesa typically costs $150,000-$280,000 ($175-$350 per sq ft); a garage conversion runs $80,000-$150,000.
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| Average Build Cost | $150,000-$280,000 |
| Cost per Sq Ft | $175-$350 |
| Garage Conversion | $80,000-$150,000 |
| Prefab ADU (Installed) | $150,000-$300,000 |
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Rental Income Potential [19][20][21][22][23]
A 2-bedroom ADU in Mesa rents for around $1,500-$1,750/mo, an estimated 6-11% gross rental yield (a $150,000-$280,000 detached build at $1,300-$1,700/mo, before taxes, vacancy, insurance and financing).
| Avg Rent (1 Bedroom) | $1,250-$1,500/mo |
| Avg Rent (2 Bedroom) | $1,500-$1,750/mo |
| Short-Term Rental | Yes, with a Mesa Short-Term Rental License (City Code 5-15, in force since February 1, 2023): $250 application and $250 annual renewal per unit, issued only to the deeded owner, with an Arizona TPT licence, an emergency . |
| Est. Annual ROI | 6-11% gross rental yield (a $150,000-$280,000 detached build at $1,300-$1,700/mo, before taxes, vacancy, insurance and financing) |
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Recent Law Changes
What's Changed Recently
- Ordinance 6025 (2026 Zoning Code Refinement), adopted July 27, 2026, effective August 28, 2026 per the city's code page: a lot outside the listed districts now qualifies only if the single residence is its principal use; a third ADU on 1-acre-plus lots is tied to the listed districts; an attached ADU may have no internal connection to the house; a detached ADU must sit 5 ft from the house, other ADUs and accessory buildings; uninhabitable space attached to an ADU follows accessory-building setbacks; ADUs may not be used as boarding houses
- Ordinance 5950 (2025 Zoning Code Refinement), adopted July 8, 2025, effective August 7, 2025: rewrote the 11-31-3(D) setback rules for conversions and additions (conforming and legal non-conforming buildings convert with no added setback; additions may follow an existing non-conforming line if they do not worsen it), removed ADUs from the 100%-of-house cap on combined detached accessory floor area in 11-30-17(A)(4), and defined 'Building Addition' (a common wall at least 20% of the wall's length) to decide attached versus detached
- Ordinance 5883, adopted October 7, 2024, effective November 6, 2024: repealed and replaced MZO 11-31-3 to comply with ARS 9-461.18, allowing one attached and one detached ADU on any lot with a single residence in any district, raising the size cap to 75% of the house or 1,000 sq ft, setting 5-ft side and rear setbacks, removing the lot-size minimum and parking requirement, and waiving covered-parking replacement for garage conversions
- Arizona HB 2720 (2024; ARS 9-461.18) required cities over 75,000 residents to allow one attached and one detached ADU by right by January 1, 2025 and bars owner-occupancy and relationship tests, added parking, design-matching, sprinkler mandates and side/rear setbacks over 5 ft; unamended as of September 2026
- ARS 9-461.20 requires every Arizona city to offer at least three preapproved ADU design plans (200, 600 and 1,000 sq ft) from July 1, 2026 and to accept outside plan submissions; Mesa's Preapproved Housing Design Plan Program now accepts Class 4 ADU plans
- ARS 9-500.39(B)(9) lets cities require a short-term-rental owner to live on the property when the lot's ADU was finaled on or after September 14, 2024; Mesa's Short-Term Rental License rules (City Code 5-15) do not include this condition as of September 2026
Tips for Building an ADU in Mesa
- Size math: measure interior habitable area only (garages and unconditioned space excluded). A 1,000 sq ft house allows a 750 sq ft ADU, a 1,200 sq ft house 900 sq ft, and any house of 1,334 sq ft or more the full 1,000 sq ft (11-31-3(C)); the lot-coverage limit of your RS district can bind before the size cap does
- Garage conversions are the cheapest path: no parking replacement (11-31-3(G)), and since Ordinance 5950 a garage that meets accessory-building setbacks or is legal non-conforming converts with no added setback; only a new addition must meet the 5-ft rule
- Utilities: 11-31-3(H) requires the ADU to share the house's water, sewer and electric providers and meters, while the city's ADU FAQ says separate meters or sub-meters can be permitted. Ask Permit Services which applies before designing a separate service, budget for panel capacity, and check recorded easements: no accessory building may encroach on a recorded easement (11-30-17(A)(5)) and an ADU cannot sit on a public utility easement without the utility's written consent (11-31-3(H)(3))
- Commercial, mixed-use and downtown lots qualify, but since Ordinance 6025 the existing single residence must be the lot's principal use; HOA CC&Rs can still restrict or prohibit ADUs (ARS 9-461.18(C); city ADU page)
- Cost basis (2026-09-20 re-verification): avg build cost $150,000-$280,000 for a mid-range 500-800 sq ft detached casita in the Phoenix-Mesa metro (Rise Above Remodeling 2026 guide $150,000-$250,000; Fenn Rogers, a Mesa builder, May 2026 $150,000-$250,000, custom $250,000-$400,000+); cost per sq ft $175-$350 (Rise Above $150-$230 typical, $230-$300+ high-end; Fenn Rogers $200-$400+); garage conversion $80,000-$150,000 (both guides); prefab/modular $150,000-$300,000 installed (Dwelling Index May 2026: $200,000-$400,000 all-in, factory unit $100,000-$250,000). Rents: HUD FY2027 Small Area FMR for Mesa ZIPs 1BR $1,260-$1,710 and 2BR $1,450-$1,990 (central Mesa 85201-85210 about $1,300-$1,350 and $1,510-$1,570), MSA FMR $1,493/$1,734, RentCafe Aug 31, 2026 $1,313/$1,599
- Cost basis (2026-09-20 re-verification): short term allowed: Yes, with a Mesa Short-Term Rental License (City Code 5-15, in force since February 1, 2023): $250 application and $250 annual renewal per unit, issued only to the deeded owner, with an Arizona TPT licence, an emergency contact and $500,000 liability insurance; the city's ADU page confirms an ADU rented for 29 days or fewer needs the licence. ARS 9-500.39(B)(9) now lets a city require the owner to live on the property when the ADU was finaled on or after September 14, 2024, but Mesa's licence page shows no such rule as of September 2026
ADU Builders in Mesa
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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 - repeal and replacement of MZO 11-30-17 and 11-31-3 (Accessory Dwelling Unit), adopted Oct 7, 2024 (Legistar file 24-0924) Municipal Code — Accessed 2026-09-20
- Mesa Ordinance No. 5950 - 2025 Zoning Code Refinement (11-30-17(A), 11-31-3(D) setbacks, Building Addition definition), adopted July 8, 2025 (Legistar file 25-0567) Municipal Code — Accessed 2026-09-20
- Mesa City Council Report - 2025 Zoning Code Refinement text amendment (ADU setbacks, accessory floor area), July 1, 2025 Planning Department — Accessed 2026-09-20
- Mesa Ordinance No. 6025 - 2026 Zoning Code Refinement Text Amendment, Exhibit 2 (amended 11-30-17(B) and 11-31-3), adopted July 27, 2026 (Legistar file 26-0621) Municipal Code — Accessed 2026-09-20
- Development Codes, Ordinances, Regulations & Standards - City of Mesa (Ord. 6025 effective August 28, 2026; adopted building codes) Planning Department — Accessed 2026-09-20
- Accessory Dwelling Units (ADUs) FAQ - City of Mesa Planning Division Planning Department — Accessed 2026-09-20
- Mesa Zoning Ordinance Section 11-31-3 Accessory Dwelling Unit - Municode (codified text) Municipal Code — Accessed 2026-06-10
- ARS 9-461.18 - Accessory dwelling units; regulation; applicability; definitions (HB 2720, 2024) State Law — Accessed 2026-09-20
- Residential Construction permits - City of Mesa Development Services (DIMES portal, required documents, 10-working-day review, expedited review) Planning Department — Accessed 2026-09-20
- City of Mesa Schedule of Fees and Charges - Development Services (Residential Rate Table, deposits, re-submittals, expedited premiums, Solid Waste Residential Development Fee), updated for July 2026 Planning Department — Accessed 2026-09-20
- City of Mesa Development Impact Fee Report and Impact Fee Schedule as of June 30, 2025 (Public Safety and Water impact fees per dwelling unit) Planning Department — Accessed 2026-09-20
- Water and Wastewater Capacity Fee - City of Mesa Utilities (effective January 1, 2026; Mesa City Code 8-10-13) Planning Department — Accessed 2026-09-20
- Preapproved Housing Design Plan Program - City of Mesa (Class 4 ADU plans: 200, 600 or 1,000 sq ft) Planning Department — Accessed 2026-09-20
- ARS 9-461.20 - Municipal housing; standard preapproved housing design plans (Class 4 ADU plans from July 1, 2026) State Law — Accessed 2026-09-20
- Mesa City Code Title 5 Ch. 17 - Development Impact Fees (Municode) Municipal Code — Accessed 2026-06-10
- ADUs in Arizona: Rules, Costs, What to Know (2026) - Fenn Rogers Custom Homes, Mesa (updated May 12, 2026) industry — Accessed 2026-09-20
- How Much Does It Cost to Build a Casita in Arizona? (2026 Guide) - Rise Above Remodeling, Phoenix industry — Accessed 2026-09-20
- Prefab Modular ADU: 2026 Costs, Code Paths & Lot Fit - Dwelling Index (updated May 27, 2026) industry — Accessed 2026-09-20
- HUD FY 2027 Small Area Fair Market Rent Schedule - Phoenix-Mesa-Chandler, AZ MSA ZIP codes 85201-85216 Government Data — Accessed 2026-09-20
- HUD FY 2027 Fair Market Rent Schedule - Phoenix-Mesa-Chandler, AZ MSA Government Data — Accessed 2026-09-20
- RentCafe - Average Rent in Mesa, AZ (updated August 31, 2026: 1BR $1,313, 2BR $1,599) Market Data — Accessed 2026-09-20
- Short-Term Rental License - City of Mesa Licensing (City Code 5-15; $250 licence; ARS 9-500.39) Planning Department — Accessed 2026-09-20
- ARS 9-500.39 - Limits on regulation of vacation rentals and short-term rentals (subsection B.9, ADU owner residency) State Law — Accessed 2026-09-20
Frequently Asked Questions
Can I build an ADU in Mesa?
Yes. ADUs are allowed in Any lot in a district where a single residence is allowed: Agricultural (AG), Single Residence (RS), Small Lot Single Residence (RSL), Multiple Residence (RM), Downtown Residence (DR), Mixed Use (MX) and the NC, LC and GC commercial districts; a lot in any other district qualifies if its principal use is an existing single residence (MZO 11-31-3(A), Ord. 6025). Historic Districts need a Certificate of Appropriateness (Ch. 74); ARS 9-461.18(G) excludes tribal land and airport-noise areas. in Mesa. The maximum size for a detached ADU is 75% of the primary residence's interior habitable area or 1,000 sq ft, whichever is less (11-31-3(C)); a 1,200 sq ft house allows up to 900 sq ft, a house of 1,334 sq ft or more allows the full 1,000. Since Ord. 5950 (Aug 2025) the ADU no longer counts toward the cap on combined detached accessory floor area in 11-30-17(A)(4). District lot-coverage and building-coverage limits still apply (11-31-3(E)).. Owner-occupancy is not required, so you can rent out the ADU.
How much does an ADU cost in Mesa?
ADU construction in Mesa typically costs $150,000-$280,000. Garage conversions run $80,000-$150,000, and prefab ADUs cost $150,000-$300,000.
How much can I rent an ADU for in Mesa?
Average ADU rents in Mesa are $1,250-$1,500/mo for a 1-bedroom and $1,500-$1,750/mo for a 2-bedroom unit.
Do I need parking for an ADU in Mesa?
None. No additional parking spaces are required for an ADU, and a garage or carport converted to an ADU need not have its covered parking replaced elsewhere on the lot (11-31-3(G)); ARS 9-461.18(B)(3) bars parking requirements and in-lieu fees. The city's ADU page notes the primary residence must still keep its own two required spaces.. 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 Written plan-review comments or approval within 10 working days (Monday-Thursday, excluding holidays) per Mesa's Residential Construction page; an expedited 5-working-day review costs an extra 100% of the permit fee. Allow for at least one re-submittal cycle.. Permit fees: Valuation-based (Development Services Schedule of Fees, July 2026): $500 plus $6 per $1,000 of valuation over $25,000, up to $200,000; then $1,550 plus $9 per $1,000. A $150,000 ADU pays about $1,250 and a $250,000 unit about $2,000, plan review and trade permits included.
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