When zoning changes, the questions change: casitas, ADUs and fourplexes

Arizona rewrote its rules for a second home on a lot and for buildings of two to four homes, Florida leaves the choice to each city and county, and a builder's website can answer the questions that follow.

Arizona law requires every city of more than 75,000 people to allow casitas, the local name for an accessory dwelling unit (ADU), since January 1, 2025, and to allow duplexes, triplexes, fourplexes and townhomes on single-family lots within one mile of its downtown since January 1, 2026. Florida leaves ADUs to each local government. Every city wrote its own ordinance, so a builder's website needs one dated page per city that names the ordinance and states its rule.

What are an ADU, a casita and middle housing?

An accessory dwelling unit, shortened to ADU, is a second small home on the same lot as a main house. In Arizona people call the same building a casita: the City of Tucson titles its worksheet "Want to Build a Casita?", while the City of Phoenix publishes an "Accessory Dwelling Unit (ADU) Guide". Middle housing is the name Arizona's statute gives to duplexes, triplexes, fourplexes and townhomes, that is, two, three or four homes on one lot, and attached homes built in a row.

Why should a builder care which of these words appears on the website? Google's Starter Guide for website owners advises them to think about the words a person types, and notes that people who know a topic well may search with different words from people who are new to it. The homeowner says casita, the city code says accessory dwelling unit, and a page that uses both names speaks to both readers.

What did Arizona change for duplexes, triplexes, fourplexes and townhomes?

House Bill 2721, approved by the Governor on May 21, 2024, is now section 9-462.13 of the Arizona Revised Statutes, written A.R.S. 9-462.13. It applies to every municipality with a population of 75,000 persons or more. On or before January 1, 2026, each of those cities had to allow duplexes, triplexes, fourplexes and townhomes as a permitted use in two places: on all lots zoned for single-family residential use within one mile of the city's central business district, and on at least 20 percent of any new development of more than ten contiguous acres.

"Permitted use" has a precise meaning in the statute: approval without a public hearing, a variance, a conditional use permit, a special permit or a special exception. In a city that missed the deadline, middle housing "shall be allowed on all lots in the municipality zoned for single-family residential use without any limitations." The statute also lists what a city may no longer do:

• Restrict middle housing to less than two floors, or to a floor area ratio under 50 percent (the floor area of the project compared with the area of the lot).
• Set rules or review steps stricter than those for single-family homes in the same zone.
• Require the owner to live on the lot.
• Require a commercial building code or a fire sprinkler.
• Require more than one off-street parking space per unit.

What did Arizona change for casitas and ADUs?

House Bill 2720, approved on the same day, became A.R.S. 9-461.18 and covers municipalities with a population of more than 75,000 persons. 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, each up to 75 percent of the gross floor area of the house or 1,000 square feet, whichever is less.

The city may not require additional parking for the ADU, may not set rear or side setbacks of more than five feet, and may not require the ADU to match the exterior design, roof pitch or finishing materials of the house. The deadline was January 1, 2025, and in a city that missed it ADUs are allowed on all residential lots "without limits".

One year later the rule went beyond city limits. House Bill 2928, approved on May 23, 2025, added A.R.S. 11-810.01, which requires counties to allow at least one attached and one detached ADU where a single-family home is allowed, with a deadline of January 1, 2026. Where there is no sewer, a county may require an adequately sized septic system.

What did each Arizona city adopt?

State law sets the minimum and, naturally, each city wrote its own ordinance to meet it. The table holds six cities whose own records we read on 29 September 2026.

Consider size alone. Mesa and Chandler keep the state figure of 75 percent of the house or 1,000 square feet. Tucson's worksheet gives 650 square feet, or 75 percent of the main house up to 1,000 square feet. Scottsdale holds a second and a third ADU to 500 square feet each. A homeowner who reads the Tucson figure on a Scottsdale builder's page has received the wrong answer.

What is Florida's position on ADUs?

Florida has no statewide ADU mandate. Section 163.31771 of the Florida Statutes reads: "A local government may adopt an ordinance to allow accessory dwelling units in any area zoned for single-family residential use." The word "may" leaves the choice to each county and city. The same section requires the applicant for an ADU building permit to file an affidavit attesting that the unit will be rented at an affordable rate.

In 2026, Senate Bill 48 would have replaced "may" with "shall" and given every local government until December 1, 2026 to adopt an ADU ordinance. The Florida Senate's page for the bill records its last action on March 13, 2026: "House - Died in Messages." A Florida builder's page about ADUs therefore has to begin with the code of the one city or county it names.

One statewide rule concerns the builder of small homes. Section 553.385 says that a home built in a factory for single-family use (the statute's term is "off-site constructed residential dwelling") "must be permitted as of right in any zoning district where single-family detached dwellings are allowed."

What do the permit counts show for two-unit and three-to-four-unit buildings?

The U.S. Census Bureau's Building Permits Survey counts the residential buildings authorized each year, grouped by the number of homes in each building. The two states moved in opposite directions. Florida's two-unit buildings rose from 1,011 to 1,323 and its three-to-four-unit buildings from 246 to 370, while its single-family permits fell from 123,359 to 111,173. In Arizona all three counts fell, and single-family homes went from 41,944 to 33,371.

Within Arizona, two-unit buildings are concentrated in the city of Phoenix, which issued permits for 354 of them in 2025. That is 73 percent of the 483 in the whole Phoenix-Mesa-Chandler metropolitan area. All of these counts end in December 2025, so they describe the two years before the middle-housing deadline of January 1, 2026.

Why does a change in zoning law matter for a builder's website?

Every rule in the city table is also a question that an owner now has reason to ask. May I build a casita behind my house in Mesa, and how large? Is my lot in Tempe inside the one-mile area where a fourplex is a permitted use? The answer depends on the city, so the question carries the city's name, and a page answers it correctly only when it states that city's rule. We hold no verified count of how many people type these questions.

We read 80 small builder websites in Arizona and Florida on 29 September 2026 wrote one note per site and kept it only when a second reading confirmed it, so each count is a minimum. On 14 of the 80, no blog or news section was linked from the homepage or the menu. On 5, no page for any city or area served was linked from the homepage. Those are the two parts of a website where a page about one city's rule sits.

The same pages serve the answers written by AI. Google now writes some answers itself, in features it calls AI Overviews and AI Mode. It says these features can issue "multiple related searches across subtopics and data sources" to build one response, and among the basics it calls worthwhile for them is this: "Making sure that important content is available in textual form." The rule itself, then, should be written out in the text of the page.

Which pages should a builder publish?

Four kinds of page answer the questions that the new rules create. Because each city's rule is different, each city page is different for a real reason, which is what separates a useful set of city pages from one page copied under six names.

• One page for each city you build in. It states that city's rule in plain words: the ordinance number and its adoption date, how many homes the lot may hold, the size limit, the setbacks and the parking rule.
• One page for each building type you sell, whether casita, duplex, triplex, fourplex or townhome, saying on which lots the law allows it.
• A block of plain questions and answers on each of those pages, written as an owner asks them. "How large can a casita be in Mesa?" "75 percent of the main house or 1,000 square feet, whichever is less, under Ordinance No. 5883."
• A project page for every finished job, once projects exist.

How do these pages stay correct when the rules change?

It must be said: these rules change. In 2026 a bill in the Arizona Legislature, HB 2375, proposed to exempt historic districts from the middle-housing rule: the House passed it on March 18, 2026, and its last recorded action is a second reading in the Senate on March 25, 2026. The statute as published on September 29, 2026 contains no such exemption. A builder's page must therefore state what is law today and label a proposal as a proposal.

Put the date you last checked the rule at the top of each page. Name the ordinance by its number. Tell the reader that the city's planning office decides what a given lot may hold, and send the reader to the city's own code or guide. Google's Starter Guide gives the same advice to every website: "Check in on previously published content and update it as needed."

Licheo builds these pages and updates them as part of its monthly work for a builder. The service has one flat monthly fee, month to month, with no contract; contact us for pricing.

Part of a larger guide

This page is one part of Home builder marketing. The other parts:

• The builder's website
• AI assistants and builders
• City and community pages
• Project pages
• For small developers
• What to measure

Questions people ask

Is a casita the same thing as an ADU in Arizona?

Yes, a casita and an ADU are the same building in Arizona: a second small home on the same lot as a main house. The statute, A.R.S. 9-461.18, uses the term accessory dwelling unit, and the City of Tucson's worksheet uses the word casita. Under that statute a city of more than 75,000 people must allow at least one attached and one detached ADU on any lot where a single-family home is allowed.

How large can a casita be under Arizona's ADU law?

A casita under Arizona's ADU law can be 75 percent of the gross floor area of the main house or 1,000 square feet, whichever is less. That is the size A.R.S. 9-461.18 obliges each covered city to allow. Cities then add their own figures: Scottsdale's Ordinance 4687 holds a second and a third ADU to 500 square feet, and Tucson's worksheet gives 650 square feet, or 75 percent of the main house up to 1,000.

Which Arizona cities had to allow duplexes, triplexes and fourplexes by January 1, 2026?

Every Arizona municipality with a population of 75,000 persons or more had to allow duplexes, triplexes, fourplexes and townhomes by January 1, 2026, under A.R.S. 9-462.13. The rule covers all lots zoned for single-family residential use within one mile of the city's central business district, and at least 20 percent of any new development of more than ten contiguous acres. Phoenix, Tucson, Mesa, Scottsdale, Chandler and Tempe have each adopted a middle housing ordinance or code amendment.

What happens when an Arizona city misses the middle housing deadline?

When an Arizona city misses the middle housing deadline, the statute removes the city's limits altogether. A.R.S. 9-462.13 says that if a municipality fails to adopt its regulations on or before January 1, 2026, middle housing "shall be allowed on all lots in the municipality zoned for single-family residential use without any limitations." The ADU statute, A.R.S. 9-461.18, carries a parallel rule tied to January 1, 2025.

Can an Arizona city require extra parking for a casita?

No, an Arizona city covered by A.R.S. 9-461.18 cannot require extra parking for a casita, and it cannot charge a fee in place of parking. City ordinances repeat the point: Mesa's Ordinance No. 5883 says "No additional parking spaces are required for an ADU," and Tucson's worksheet says there are no parking requirements for casitas. For duplexes to fourplexes the separate statute lets a city require up to one off-street space per unit.

Does Florida require cities and counties to allow ADUs?

No, Florida has no statewide law that requires cities and counties to allow ADUs. Section 163.31771 of the Florida Statutes says a local government "may" adopt an ordinance to allow them in areas zoned for single-family residential use. Senate Bill 48 would have made that a duty with a date of December 1, 2026, and the Florida Senate records that the bill died in the House on March 13, 2026. Each Florida city or county therefore decides for itself.

Do Arizona counties have to allow casitas outside city limits?

Yes, Arizona counties have had to allow casitas since January 1, 2026. House Bill 2928, approved on May 23, 2025, added A.R.S. 11-810.01, which requires a county to 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 additional parking. Where no sewer exists, the county may require an adequately sized septic system.

How many two-unit buildings did Phoenix permit in 2025?

The city of Phoenix issued permits for 354 two-unit buildings in 2025, according to the U.S. Census Bureau's Building Permits Survey. That is 73 percent of the 483 two-unit buildings permitted in the whole Phoenix-Mesa-Chandler metropolitan area that year. In 2024 the city's count was 470. Across Arizona, two-unit buildings fell from 927 in 2024 to 589 in 2025, in the same period in which Florida's rose from 1,011 to 1,323.

Should a builder write one casita page for all of Arizona or one for each city?

A builder should write one casita page for each city, because each city adopted its own ordinance with its own figures. Tucson's Ordinance No. 12131 took effect on November 21, 2024 and its worksheet allows two casitas on a parcel with one house, while Scottsdale's Ordinance 4687, adopted on September 30, 2025, requires at least 10 feet between the ADU and the main house. One statewide page cannot state both rules correctly for both owners.

Can a fourplex be approved in Arizona without a public hearing?

Yes, a fourplex can be approved in Arizona without a public hearing on a lot where the middle housing statute applies. A.R.S. 9-462.13 makes duplexes, triplexes, fourplexes and townhomes a "permitted use" on single-family lots within one mile of the central business district, and it defines permitted use as approval without a public hearing, variance, conditional use permit, special permit or special exception. Tempe, for example, still asks for a landscape plan through its development plan review.

Sources

1. A.R.S. 9-462.13, Zoning; development; middle housing; applicability; definitions, Arizona State Legislature. Accessed 29 September 2026.
2. Chapter 197, Laws 2024 (HB 2721), Arizona State Legislature. Accessed 29 September 2026.
3. A.R.S. 9-461.18, Accessory dwelling units; regulation; applicability; definitions, Arizona State Legislature. Accessed 29 September 2026.
4. Chapter 196, Laws 2024 (HB 2720), Arizona State Legislature. Accessed 29 September 2026.
5. Chapter 217, Laws 2025 (HB 2928), Arizona State Legislature. Accessed 29 September 2026.
6. HB 2375: housing; zoning; historic neighborhoods (House summary), Arizona House of Representatives Majority Research Staff. Accessed 29 September 2026.
7. HB 2375 action history (a bill tracker, used for dates only), FastDemocracy. Accessed 29 September 2026.
8. Welcome to the City of Phoenix's Accessory Dwelling Unit (ADU) Guide, City of Phoenix Planning and Development Department. PDF created 2025-04-16, accessed 29 September 2026.
9. File 24-1862, Accessory Dwelling Units, Z-TA-2-24-Y (Ordinance G-7317), City of Phoenix Legistar. Accessed 29 September 2026.
10. Middle Housing Text Amendment and Overlay District, City of Phoenix. Accessed 29 September 2026.
11. File 25-2234, Middle Housing text amendment (Ordinance G-7446), City of Phoenix Legistar. Accessed 29 September 2026.
12. City Council Formal Meeting Report, Agenda Date 11/19/2025, Item No. 72 (Ordinance G-7447), City of Phoenix. Accessed 29 September 2026.
13. Accessory Dwelling Units Code Amendment, City of Tucson. Accessed 29 September 2026.
14. Want to Build a Casita? Worksheet, City of Tucson Planning and Development Services. Worksheet dated 2025-05-19, accessed 29 September 2026.
15. Tucson Expands Housing Options with Middle Housing Code Amendment Approval, City of Tucson PDSD News. Published 2025-12-17, accessed 29 September 2026.
16. Ordinance No. 12219 (Middle Housing), signed copy, City of Tucson. Adopted 2025-12-16, accessed 29 September 2026.
17. Ordinance No. 5883 (accessory dwelling units), City of Mesa. Accessed 29 September 2026.
18. Ordinance No. 5989 (middle housing), attachment to File 25-1006, City of Mesa. Accessed 29 September 2026.
19. Council Report, File 25-1006 (middle housing), City of Mesa. Accessed 29 September 2026.
20. Accessory Dwelling Units (ADUs), City of Scottsdale. Accessed 29 September 2026.
21. Middle Housing, City of Scottsdale. Accessed 29 September 2026.
22. Ordinance No. 5113 (city code amendments, state housing mandates), City of Chandler. Accessed 29 September 2026.
23. Meeting Minutes, City Council Regular Meeting, November 13, 2025, City of Chandler. Accessed 29 September 2026.
24. Section 3-402, Accessory Dwelling Units, Tempe Zoning and Development Code, City of Tempe, published by Municode. Accessed 29 September 2026.
25. Part 5, Chapter 8, Middle Housing Overlay District, Tempe Zoning and Development Code, City of Tempe, published by Municode. Accessed 29 September 2026.
26. Section 163.31771, Accessory dwelling units, The 2026 Florida Statutes, The Florida Legislature, Online Sunshine. Accessed 29 September 2026.
27. CS/CS/SB 48 (2026): Housing, bill page and bill text, The Florida Senate. Accessed 29 September 2026.
28. Section 553.385, Zoning of off-site constructed residential dwellings; parity, The 2026 Florida Statutes, The Florida Legislature, Online Sunshine. Accessed 29 September 2026.
29. Building Permits Survey, annual state file 2024 (st2024a.txt), U.S. Census Bureau. Accessed 29 September 2026.
30. Building Permits Survey, annual state file 2025 (st2025a.txt), U.S. Census Bureau. File last modified 2026-05-14, accessed 29 September 2026.
31. Building Permits Survey, annual metropolitan area file 2024 (cbsa2024a.txt), U.S. Census Bureau. Accessed 29 September 2026.
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33. Building Permits Survey, annual place file, West Region, 2024 (we2024a.txt), U.S. Census Bureau. Accessed 29 September 2026.
34. Building Permits Survey, annual place file, West Region, 2025 (we2025a.txt), U.S. Census Bureau. File last modified 2026-05-14, accessed 29 September 2026.
35. Search Engine Optimization (SEO) Starter Guide, Google Search Central. Updated 2025-12-10, accessed 29 September 2026.
36. AI features and your website, Google Search Central. Updated 2025-12-10, accessed 29 September 2026.
37. What 80 small builder websites in Arizona and Florida get wrong (Licheo's own reading of the websites), Licheo. Websites read twice on 29 September 2026.

Keep reading

• Home builder marketing: the complete guide
• Service area pages for builders
• Marketing for small developers
• What a small builder's website needs
• How AI assistants choose which builder to name
• Arizona's middle housing law and how builders get found
• Arizona casita and ADU rules, city by city
• Florida ADU rules for small builders
• Search engine optimization for home builders
• Run the free Get Found Check

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