Casita and ADU rules in six Arizona cities, and what a casita builder's website should answer

By licheo Research Team | | Local SEO | 10 min read

Arizona law requires cities of more than 75,000 people to allow at least one attached and one detached casita on a single-family lot, and each city wrote its own rules on size, height and setbacks. Here are the rules in Phoenix, Tucson, Mesa, Scottsdale, Chandler and Tempe, with the ordinance behind each, and the questions a casita builder's website should answer for every city it serves.

Casita and ADU rules in six Arizona cities, and what a casita builder's website should answer

How big can a casita be? In Scottsdale, the first one can have 1,000 square feet or 75 percent of the main house, whichever is less, and a second or third is limited to 500 square feet. In Tucson, the city's worksheet says up to 650 square feet, or 75 percent of the main house up to 1,000 square feet. The homeowner who asks is asking about one city, and a builder's website that gives one general answer for all of Arizona leaves both of these homeowners without theirs.

A casita is what planners call an accessory dwelling unit (shortened to ADU): a second small home on the same lot as a house. Arizona passed a state law on casitas in 2024 and extended it in 2025, and each city then wrote its own ordinance. Before the rules, one caution: this article is marketing guidance, and a city can amend its ordinance at any council meeting, so read the city's current code before you quote a rule to a client.

What does Arizona's casita law require of a city?

The law began as House Bill 2720, approved by the Governor on May 21, 2024 (Laws 2024, Chapter 196), and it is now section 9-461.18 of the Arizona Revised Statutes, written A.R.S. 9-461.18. It covers municipalities with a population of more than 75,000 persons, and its deadline was January 1, 2025.

On any lot where a single-family home is allowed, the city must allow at least one attached and one detached ADU as a permitted use. On a lot of one acre or more it must allow one more detached ADU, if at least one ADU on the lot is rented as restricted-affordable housing (for households earning up to 80 percent of the area median income). The city must allow an ADU of 75 percent of the gross floor area of the house or 1,000 square feet, whichever is less.

The statute also limits the city. A city may not ban renting the house or the ADU separately as a long-term rental (90 days or longer, or month to month). It may not require a family, marital or employment relationship between the owner and the person living in the ADU. It may not require extra parking, or a fee in place of parking. It may not require the ADU to match the house in exterior design, roof pitch or materials. It may not set a rear or side setback (the required distance between a building and the property line) of more than five feet. And it may not require a commercial building code or a fire sprinkler.

For a city that missed the deadline, the statute says ADUs "shall be allowed on all lots or parcels zoned for residential use in the municipality without limits."

What did HB 2928 change in 2025?

House Bill 2928, approved by the Governor on May 23, 2025 (Laws 2025, Chapter 217), made two changes that concern a casita builder. First, it added A.R.S. 11-810.01, which extends the ADU rules to counties: at least one attached and one detached ADU where a single-family home is allowed, no side or rear setback over five feet, and no extra parking. The county deadline was January 1, 2026, and a county may require an adequately sized septic system where there is no sewer.

Second, it changed the short-term rental statute, A.R.S. 9-500.39. A city or town may now require the owner of a short-term rental to live on the property, if the property contains an ADU built on or after September 14, 2024 that is used as a short-term rental.

What are the casita rules in Phoenix, Tucson, Mesa, Scottsdale, Chandler and Tempe?

The table gives what each city's own documents say; "sq ft" means square feet.

| City | Ordinance | Casitas per lot | Size limit | Side and rear setback | Height | Parking | |---|---|---|---|---|---|---| | Phoenix | G-7317 (status "Adopted"; the city record shows no adoption date) | Two; a third on a lot of at least one acre if one is deed-restricted affordable | Lots up to 10,000 sq ft: 1,000 sq ft or 75% of the main house, whichever is less | Detached: 3 feet from an interior property line, 5 feet from a street-side line | 15 feet for a detached ADU, unless a use permit allows more | A converted garage or carport must be replaced with parking on the lot | | Tucson | No. 12131, adopted October 22, 2024 | Two with one existing house; a third on a parcel over one acre if one is deed-restricted affordable | Up to 650 sq ft, or 75% of the main house up to 1,000 sq ft | 5 feet minimum | The zone's maximum for a single-family house ("generally 25 ft") | "There are no parking requirements for casitas." | | Mesa | No. 5883, adopted October 7, 2024 | One attached and one detached; one more detached on one acre or more if one is rented as restricted-affordable | 75% of the main house or 1,000 sq ft, whichever is less | 5 feet minimum | Absent from the document we read | "No additional parking spaces are required for an ADU." | | Scottsdale | 4687, adopted September 30, 2025 | One attached and one detached; a third detached on one acre or more if one is affordable housing | First ADU: 1,000 sq ft or 75% of the main house, whichever is less. Second and third: 500 sq ft | Detached: as close as 5 feet to a side or rear yard | The district maximum | Parking for the main house must be kept | | Chandler | No. 5113, adopted December 9, 2024 | One attached and one detached; one more detached on one acre or more if one is restricted-affordable | 75% of the house's interior habitable area or 1,000 sq ft, whichever is less | "no less than five (5) feet" | The district limit | No rule quoted here (see below) | | Tempe | Section 3-402 (Ord. No. O2024.51, November 21, 2024) | One attached and one detached on a lot under one acre; one more on one acre or more if one is restricted-affordable | 1,000 sq ft or 75% of the main house, whichever is less; on one acre or more, 2,000 sq ft or 75% | 5 feet minimum | Same as the district | "No additional vehicle parking is required for an ADU." |

Phoenix. The city's ADU guide allows two ADUs on each single-family detached lot, and none on a lot with a duplex or a triplex. On lots over 10,000 square feet the limit is 3,000 square feet, 10 percent of the net lot area, or 75 percent of the main house, whichever is less. A detached ADU can sit in the required rear yard, and at 0 feet from a property line on a fully dedicated alley.

Tucson. Ordinance No. 12131 took effect on November 21, 2024. The current rules are in the city's casita worksheet dated May 19, 2025, which also allows one casita on a parcel with a duplex, keeps casitas out of the front yard and requires a cool roof on new structures. The city's amendment page still shows older summary text that conflicts with the worksheet, so confirm which document is current before you publish.

Mesa. Ordinance No. 5883 sets no minimum lot size, and front and street-side setbacks follow those of the main house.

Scottsdale. The city asks for at least 10 feet between the ADU and the main house and for separate utility metering. It allows no more than six adults in total to live on the lot.

Chandler. The rules are in a new Section 35-2202.2 of the city code. We quote no parking rule for Chandler, because the copy of the ordinance we read leaves unclear whether an older parking line was removed.

Tempe. An ADU limited to 1,000 square feet can have no more than three bedrooms. The ADU counts toward lot coverage and needs its own address.

How long does plan review take in each city?

Before a city issues a building permit, its staff check the drawings, a step called plan review. We found a published time for five of the six cities.

| City | Published time for residential plans | |---|---| | Phoenix | Goal of 30 calendar days for the initial plan review of a new home with a full set of plans; the average in the previous month was 30 (report for July 2026) | | Tucson | Performance goal of 10 business days in the city's Fast Lane, which covers a new residential dwelling and a residential ADU or casita | | Mesa | "within 10 working days. Working days are Monday through Thursday, excluding holidays."; 5 working days for an extra fee | | Scottsdale | 7 business days for the first stage (administrative review) and 15 business days for the second (substantive review) | | Chandler | 20 working days per review for a custom home; 10 working days for a home built from standard plans (PDF created June 14, 2018) |

The Chandler document dates from 2018, so confirm its times with the city before you repeat them. For Tempe we found no review time on a city page that loaded. Tucson's lane names the casita itself; the other four documents give times for residential plans in general, so ask the permit office which line applies to a casita.

What should a casita builder's website answer for each city?

Google's starter guide for site owners says: "Think about the words that a user might search for to find a piece of your content." A homeowner's words are a question with a city in it. "Can I build a casita in Mesa?" "How big can an ADU be in Scottsdale?" "How close to the property line can a casita sit in Phoenix?" "Do I need extra parking for a casita in Tempe?" "Can I rent out my casita?" Each of these has an answer in the table above or in the state law. Each belongs on the page for that city, written as a heading with the answer directly beneath it in one or two plain sentences, and with the ordinance number beside it.

So the first thing to publish is one page for each city you serve, with that city's numbers. This is also what keeps city pages from being copies of each other. Google's spam policies define a practice they call doorway abuse as the case "when sites or pages are created to rank for specific, similar search queries", and one of Google's examples is a set of pages aimed at specific regions or cities that all send the visitor on to one page. A Tucson page that says 650 square feet and a cool roof, and a Scottsdale page that says 500 square feet for the second casita and six adults per lot, are two different pages, each useful to the person who arrives on it. Our guide to service area pages explains how to build them, and the guide to ADU and middle housing pages covers the casita pages themselves.

The second thing is one page for each finished casita: the city, the size in square feet, attached or detached, and how long the plan review took. Our guide to project pages gives the structure.

How do builders' websites compare with this today?

When we read 80 small builder websites in Arizona and Florida on September 29, 2026, 5 had no page for any city or area served linked from the homepage. On one more, the homepage title and main heading were aimed at a different service from the one the builder sells: they said "General Contractor" and left out both the custom homes and the ADUs the business builds. We wrote one note per site and kept it only when a second reading confirmed it, so every count is a minimum. The full results are in what 80 small builder websites get wrong in Arizona and Florida.

In the National Association of REALTORS survey of people who bought a home between July 2023 and June 2024, 43 percent looked online for properties as their first step, and 1 percent contacted a builder or visited builder models. The survey is national and describes home buyers, so apply it to casita clients with care.

Duplexes to fourplexes follow a separate state law, described in Arizona's middle housing law: what six cities adopted. Licheo does the website, search and AI work that big companies pay whole teams for, for small businesses, at one flat monthly fee, month to month, with no contract (contact us for pricing), and our home builder marketing guide explains the work. To see how findable your own site is today, run the free Get Found Check: you enter your website address, and in under 60 seconds it returns a letter grade from A to F with a score out of 100. It reads one page, so treat the grade as a place to start.

Sources

  1. Chapter 0196, 562R, S Ver of HB2720, Arizona State Legislature, approved May 21, 2024, accessed 29 September 2026.
  2. A.R.S. 9-461.18, Arizona State Legislature, accessed 29 September 2026.
  3. Chapter 0217, 571R, S Ver of HB2928, Arizona State Legislature, approved May 23, 2025, accessed 29 September 2026.
  4. Welcome to the City of Phoenix's Accessory Dwelling Unit (ADU) Guide, City of Phoenix Planning and Development Department, PDF created April 16, 2025, accessed 29 September 2026.
  5. File 24-1862, Accessory Dwelling Units, Z-TA-2-24-Y (Ordinance G-7317), City of Phoenix Legistar, accessed 29 September 2026.
  6. Plan Reviews: Turnaround Times for July 2026, City of Phoenix Planning and Development, accessed 29 September 2026.
  7. Accessory Dwelling Units Code Amendment, City of Tucson, accessed 29 September 2026.
  8. Want to Build a Casita? Worksheet, City of Tucson Planning and Development Services, dated May 19, 2025, accessed 29 September 2026.
  9. Ordinance No. 5883, City of Mesa, adopted October 7, 2024, accessed 29 September 2026.
  10. Residential Construction, City of Mesa Development Services, accessed 29 September 2026.
  11. Accessory Dwelling Units (ADUs), City of Scottsdale, accessed 29 September 2026.
  12. Residential Plan Review, City of Scottsdale, accessed 29 September 2026.
  13. Ordinance No. 5113, City of Chandler, adopted December 9, 2024, accessed 29 September 2026.
  14. Development Services Time Frames, City of Chandler, PDF created June 14, 2018, accessed 29 September 2026.
  15. Section 3-402, Accessory Dwelling Units, Tempe Zoning and Development Code, Municode, codified through the ordinance of July 1, 2026, accessed 29 September 2026.
  16. 2025 Home Buyers and Sellers Generational Trends Report, National Association of REALTORS Research Group, accessed 29 September 2026.
  17. Search Engine Optimization (SEO) Starter Guide, Google Search Central, last updated 2025-12-10, accessed 29 September 2026.
  18. Spam policies for Google web search, Google Search Central, last updated 2026-08-28, accessed 29 September 2026.
  19. Permit Review Lanes, City of Tucson Planning and Development Services, accessed 29 September 2026.

Frequently asked questions

How many casitas does Arizona law let me build on one single-family lot?

Arizona law, A.R.S. 9-461.18, requires cities of more than 75,000 persons to allow at least one attached and one detached casita on any lot where a single-family home is allowed. On a lot of one acre or more, the city must allow one more detached casita if at least one ADU on the lot is rented as restricted-affordable housing, for households earning up to 80 percent of the area median income.

How big can an ADU be in Scottsdale?

In Scottsdale, the first ADU on a property can be 1,000 square feet or 75 percent of the main house, whichever is less, and a second or third ADU is limited to 500 square feet. These limits come from Ordinance 4687, adopted on September 30, 2025. Scottsdale also asks for at least 10 feet between the ADU and the main house, and for separate utility metering.

How big can a casita be in Tucson?

In Tucson, a casita can be up to 650 square feet, or 75 percent of the main house up to 1,000 square feet, according to the city's casita worksheet dated May 19, 2025. The side and rear setback is 5 feet minimum, the casita stays out of the front yard, and the worksheet says there are no parking requirements for casitas. Mayor and Council adopted Ordinance No. 12131 on October 22, 2024.

Can I build a casita in Mesa, and is there a minimum lot size?

Yes, Mesa allows one attached and one detached ADU on a lot where a single residence is allowed, and Ordinance No. 5883, adopted on October 7, 2024, sets no minimum lot size. The interior habitable area is limited to 75 percent of the main house or 1,000 square feet, whichever is less. Side and rear setbacks are 5 feet minimum, and the ordinance says no additional parking spaces are required for an ADU.

How close to the property line can a detached casita sit in Phoenix?

In Phoenix, a detached casita can sit no closer than 3 feet to an interior property line and 5 feet to a street-side property line, and at 0 feet from a property line on a fully dedicated alley, according to the city's ADU guide. The same guide limits a detached ADU to 15 feet in height unless a use permit allows more, and it lets the ADU sit in the required rear yard.

Do I need to add a parking space to build a casita in Arizona?

Arizona's casita law, A.R.S. 9-461.18, bars a covered city from requiring extra parking for an ADU, or a fee in place of parking. Tempe's code says no additional vehicle parking is required for an ADU, Mesa's ordinance says no additional parking spaces are required, and Tucson's worksheet says there are no parking requirements for casitas. In Phoenix, a garage or carport converted to an ADU must be replaced with parking elsewhere on the lot.

Can I rent out my casita in Arizona?

Under A.R.S. 9-461.18, an Arizona city covered by the casita law cannot ban renting the house or the casita separately as a long-term rental, which the statute describes as 90 days or longer, or month to month. Short-term rental follows a different rule: since HB 2928 in 2025, a city or town can require the owner to live on the property if an ADU built on or after September 14, 2024 is used as a short-term rental.

How long does plan review take for a residential project in Phoenix, Mesa and Scottsdale?

Phoenix reports a goal of 30 calendar days for the initial plan review of a new home with a full set of plans, in its report for July 2026. Mesa says residential construction plans are reviewed within 10 working days, counting Monday through Thursday. Scottsdale lists 7 business days for administrative review and 15 business days for substantive review of single-family residential plans. Ask each city which line applies to a casita.

Do Arizona counties have to allow casitas outside city limits?

Yes, Arizona counties have to allow casitas since HB 2928, approved on May 23, 2025, added A.R.S. 11-810.01. A county must allow at least one attached and one detached ADU where a single-family home is allowed, with no side or rear setback over five feet and no extra parking. The county deadline was January 1, 2026, and a county can require an adequately sized septic system where there is no sewer.

What should a casita builder's website say for each city it serves?

A casita builder's website should have one page for each city it serves, stating that city's own rules: how many casitas per lot, the size limit, the setbacks, the height limit and the ordinance number. For Tempe, that means one attached and one detached ADU on a lot under one acre, 1,000 square feet or 75 percent of the main house, whichever is less, and 5-foot setbacks. Read the city's current code before publishing.

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