Avondale adopted its ADU rules on November 18, 2024 (Zoning Ordinance §28-33(a)), ahead of the state deadline in Arizona's casita law. ADUs are permitted with conditions in every single-family district and in R-2, R-3 and MH: one attached plus one detached per lot, 5-foot rear and side setbacks, no extra parking, and a cap of 1,000 sq ft or 75% of the house, whichever is less. Avondale then adds conditions most Valley cities do not: a two-bedroom maximum, a separate house number, a shared driveway, connection to the house's own utilities, impact fees charged as a new dwelling unit, and no short-term rental of a new ADU unless the owner lives on the property. Guest houses are no longer permitted as a category — an existing one counts as your ADU.
In Avondale 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.
Zoning & Size Requirements [1][2]
Yes — Avondale allows ADUs. A detached ADU can typically be up to 1,000 sq ft under current Arizona and Avondale zoning rules.
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| Allowed Zones | Permitted with conditions (PC) in AG, RR-43, RR-18, R1-35, R1-15, R1-10, R1-8, R1-7, R1-6 and R1-5, and in R-2, R-3 and MH; not permitted in R-4 (Avondale Zoning Ordinance §28-32 land use matrix). Only where the district allows a single-family dwelling, and never on a lot with a duplex, townhome or other multi-family development (§28-33(a)(3)(B)). Excluded: tribal land and land in the territory in the vicinity of a military airport, an FAA commercially licensed or general aviation airport, or a public airport (§28-33(a)(12)) — Luke Air Force Base and Phoenix Goodyear Airport are both nearby, so ask for a parcel check |
| Max Size (Detached) | The lesser of 75% of the gross floor area of the existing single-family dwelling or 1,000 sq ft (Avondale Zoning Ordinance §28-33(a)(3)(A)); gross floor area means interior habitable area. No more than two bedrooms (§28-33(a)(3)(G)) |
| Max Size (Attached) | Same cap — the lesser of 75% of the house's gross floor area or 1,000 sq ft, and no more than two bedrooms (§28-33(a)(3)(A), (G)) |
| Max Size (JADU) | Not a category in Arizona — Avondale's ordinance has no junior ADU designation |
| Max Height | The same height restrictions that apply to a single-family dwelling on the same lot (§28-33(a)(3)(F)) — the 15-foot cap on ordinary accessory buildings does not apply to an ADU (§28-133(e)); state law bars a stricter ADU height than the house's (A.R.S. §9-461.18(B)(5)) |
| Max Units | 2 per lot — one attached plus one detached ADU (§28-33(a)(1)(A)-(B)). On a lot of 1 acre or more: one attached plus two detached, but only if at least one is a restricted-affordable unit deed-restricted for 30 years to Arizona Department of Housing rent limits (§28-33(a)(1)(C), (8)). An existing permitted guest house begun before November 18, 2024 counts as one of your ADUs; new guest houses are not permitted (§28-33(a)(1)(D)) |
Setback Requirements [1][2]
Avondale 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 feet from the property line (§28-33(a)(3)(D)(I)); state law caps what the city may require at 5 feet (A.R.S. §9-461.18(B)(6)) |
| Side Setback | 5 feet from the property line (§28-33(a)(3)(D)(II)) — the state-law ceiling |
| Front Setback | The front yard setback of the applicable zoning district under §28-35 (§28-33(a)(3)(D)(III)); detached accessory buildings are never allowed in a front yard (§28-133(a)) |
| Parking Required | None — no additional parking space or in-lieu parking fee may be required (§28-33(a)(5); A.R.S. §9-461.18(B)(3)). But the lot may have only one driveway, shared by the house and the ADU (§28-33(a)(3)(L)) |
| Owner Occupancy | Not required to build or to rent long-term — the ordinance says outright that either the house or any ADU may be separately leased as long-term rental housing (§28-33(a)(2)(C)), matching state law. Owner residence IS required for short-term rental of any ADU issued a certificate of occupancy on or after September 14, 2024 (§28-33(a)(7)) — see the rental section |
| Min Lot Size | No ADU-specific minimum lot size — the same one-attached-plus-one-detached allowance applies below and above 1 acre (§28-33(a)(1)(A)-(B)); a lot of 1 acre or more unlocks a third unit |
Permit Process & Fees [3]
An ADU permit in Avondale goes through a standard permit review. Confirm with Avondale Development Services at (623) 333-4000 — the city recommends a call about ADU requirements before submitting, and publishes no ADU-specific review timeline. Permit fees: Building permit and plan review fees apply — confirm current amounts with Avondale Development Services.
| Approval Process | One application: a Residential Building Permit through Avondale's Accela Citizen Access portal, choosing 'Accessory Dwelling Unit' as the application type; zoning compliance with §28-33(a) is checked as part of the building plan review, so there is no separate zoning clearance step. Permitted with conditions — by right if the §28-33(a) conditions are met, though staff may add conditions at site plan review to protect health and safety (§28-33). Construction may start only after the permit issues, and a Certificate of Occupancy is required before anyone moves in (city ADU permitting guide, May 2026) |
| Review Timeline | Confirm with Avondale Development Services at (623) 333-4000 — the city recommends a call about ADU requirements before submitting, and publishes no ADU-specific review timeline |
| Permit Fees | Building permit and plan review fees apply — confirm current amounts with Avondale Development Services |
| Impact Fees | Yes — the ordinance treats an ADU as a separate or new dwelling unit for water, sewer and power service, 'including the calculation of fees' (§28-33(a)(2)(D)). Ask Development Services for the current impact fee amounts before budgeting |
| Plan Check | Full residential plan review under Avondale's building, fire and public-health codes, but the city may not require a commercial building code or a fire sprinkler (§28-33(a)(11); A.R.S. §9-461.18(D)). The ADU must connect to the same utilities as the house, and the owner must show the services are adequate and upgrade them if not (§28-33(a)(6)); it needs its own entrance and an egress path that does not pass through the main house (§28-33(a)(3)(H)) |
| Pre-Approved Plans | No city pre-approved ADU plan library found — confirm with Avondale Development Services |
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Construction Costs [4]
Building an ADU in Avondale typically costs $120,000-$245,000 ($145-$270 per sq ft); a garage conversion runs $55,000-$135,000.
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| Average Build Cost | $120,000-$245,000 |
| Cost per Sq Ft | $145-$270 |
| Garage Conversion | $55,000-$135,000 |
| Prefab ADU (Installed) | $85,000-$200,000 |
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Rental Income Potential [5][6]
A 2-bedroom ADU in Avondale rents for around $1,450-$1,850/mo, an estimated 5-8% annual return.
| Avg Rent (1 Bedroom) | $1,250-$1,550/mo |
| Avg Rent (2 Bedroom) | $1,450-$1,850/mo |
| Short-Term Rental | Only if you live on the property: an ADU issued a certificate of occupancy on or after September 14, 2024 may not be used as a vacation or short-term rental unless the owner resides on the same property (§28-33(a)(7)). Owners who can show they had a legal right to build an ADU on or before September 14, 2024 are exempt, unless the three-year limit in A.R.S. §12-1134(G) has run. Arizona TPT registration applies. Long-term leasing of the ADU on its own is expressly allowed (§28-33(a)(2)(C)) |
| Est. Annual ROI | 5-8% annual return |
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Recent Law Changes
What's Changed Recently
- Ordinance No. 2032-1124, adopted November 18, 2024, rewrote §28-33(a) of the Zoning Ordinance to allow accessory dwelling units under A.R.S. §9-461.18 ahead of the January 1, 2025 deadline, and removed new guest houses as a permitted use — an existing permitted guest house begun before that date now counts as an ADU
- Arizona HB 2720, codified at A.R.S. §9-461.18, requires every municipality over 75,000 people to allow at least one attached and one detached ADU as a permitted use wherever single-family homes are allowed — Avondale's population of about 96,600 (U.S. Census Bureau, 2024 estimate) puts it inside the mandate
- State law bars the city from requiring extra parking or in-lieu fees, exterior design matching, a city-imposed restrictive covenant, or rear/side setbacks over 5 feet (A.R.S. §9-461.18(B))
- Avondale's ordinance goes beyond the statute in several conditions: a two-bedroom maximum, a separate visible house number, a single shared driveway, connection to the house's utilities, impact fees charged as a new dwelling unit, and an owner-residence condition on short-term rental of ADUs completed on or after September 14, 2024 (§28-33(a)(2)(D), (3)(G), (3)(I), (3)(L), (6), (7))
- In May 2026 Development Services published an ADU permitting guide: apply through Accela Citizen Access as a Residential Building Permit with 'Accessory Dwelling Unit' as the type; a Certificate of Occupancy is required before occupancy; unpermitted ADUs are the current owner's responsibility
Tips for Building an ADU in Avondale
- Design for two bedrooms at most — the cap is written into the ordinance (§28-33(a)(3)(G)), and a third bedroom is not a variance-friendly ask
- Measure your house before you design: the cap is the lesser of 1,000 sq ft or 75% of your home's interior habitable area, so a 1,200 sq ft house limits the casita to 900 sq ft
- Budget the impact fees as if you were building a new house: Avondale charges water, sewer and power fees on an ADU as a new dwelling unit (§28-33(a)(2)(D)) — get the number from Development Services before you sign a contract
- If you want a vacation rental, you have to live there: a new ADU cannot be a short-term rental unless the owner resides on the property (§28-33(a)(7)); long-term tenants are fine either way
- Plan the entrance and egress early — the ADU needs its own entrance and a path to the street that never passes through the main house (§28-33(a)(3)(H)), which rules out some interior conversions
- Order the second house number: the ADU must have its own address visible from the street (§28-33(a)(3)(I)) — the opposite of Glendale and Goodyear, where a separate address is prohibited
- One driveway only: the ADU shares the existing driveway (§28-33(a)(3)(L)), so a second curb cut is not an option
- Check the airport territory: lots near Luke Air Force Base or Phoenix Goodyear Airport may be excluded (§28-33(a)(12)) — ask for a parcel check before paying for drawings
ADU Builders in Avondale
Looking for an ADU builder in Avondale? ADU projects need a contractor experienced with local zoning, the permit process, and utility connections — not every general contractor has built one. We match Avondale homeowners with experienced local ADU contractors who provide free, no-obligation quotes. Getting at least three bids typically saves 20-40% on the same scope.
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Avondale Code of Ordinances, Chapter 28 Zoning Ordinance — §28-33(a) Accessory dwelling units (Ord. No. 2032-1124, 11-18-24); §28-32 land use matrix; §28-133 detached accessory buildings; §28-15 definitions Municipal Code — Accessed 2026-09-06
- A.R.S. §9-461.18 — Accessory dwelling units; regulation; applicability; definitions state_statute — Accessed 2026-09-06
- Permitting an Accessory Dwelling Unit in Avondale — Development Services guide (May 6, 2026) Planning Department — Accessed 2026-09-06
- Angi — ADU Construction Cost Data (same source and access as the Peoria entry; West Valley ranges applied) Market Data — Accessed 2026-09-01
- RentCafe — Average Rent in Avondale, AZ (updated August 31, 2026: 1BR $1,400, 2BR $1,636; city average $1,611) Market Data — Accessed 2026-09-06
- U.S. Census Bureau — Vintage 2024 Population Estimates, sub-est2024.csv (Avondale city, AZ: 96,609) Government Data — Accessed 2026-09-06
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