It’s one of the first questions we hear from East Valley homeowners: can I build a casita in my backyard? Maybe it’s for a parent who needs to live closer, a grown kid saving for a house, guests who stay a few weeks every winter, or a little rental income.
The answer depends on where you live. Arizona changed the rules for larger cities in 2025, but not every East Valley community is covered by that law, and some have written their own. Here’s how it breaks down, city by city.
Arizona’s casita law in plain English
In 2024, Arizona passed HB 2720, which added a section to state law about accessory dwelling units. An accessory dwelling unit, or ADU, is the official name for a casita or guest house: a second, smaller home on a single-family lot.
The law applies to cities and towns with more than 75,000 residents. Those communities had to update their rules by January 1, 2025. Under the law, they must:
- Allow at least one attached and one detached casita on lots where single-family homes are allowed
- Allow a casita up to 1,000 square feet or 75% of the main home’s size, whichever is smaller
- Keep side and rear setbacks to no more than 5 feet from the property line
- Not require extra parking for the casita
- Not require a family or other relationship between the owner and whoever lives in the casita
- Not ban long-term rentals of the main home or the casita
That’s a big change. For years, many cities limited guest houses to family members or buried them in special permits. In the larger cities, a casita is now a permitted use.
Gilbert, Mesa and Chandler: the state law applies
Each of these communities has more than 75,000 residents, so HB 2720 applies. On most single-family lots, a casita is a realistic option, and a long-term rental casita is allowed under state law.
A few things still shape what you can build:
- HOA rules. The state law governs city regulations. Your HOA’s design guidelines can still add requirements about materials, height, colors and placement, so we review them during planning.
- Lot size and layout. A casita still has to fit your lot, utilities and drainage, even with smaller setbacks.
- Building codes. A casita is a real home. It goes through plan review, permits and inspections like any other new construction.
More detail for each city lives on our pages for Gilbert, Mesa and Chandler.
Queen Creek: the town’s own rules
Queen Creek writes its own accessory dwelling ordinance. That means size, height and setback limits come from the town code rather than the state rule for larger cities, and they can differ depending on your lot and zoning.
Queen Creek also has a wide range of lots, from standard subdivision lots to an acre or more with horse privileges. On bigger lots, the questions are usually about setbacks, septic versus sewer, and drainage. In master-planned neighborhoods, HOA architectural review matters just as much as the town code. We confirm all of it for your specific lot before design starts. See our Queen Creek page for more.
San Tan Valley: a brand-new town
San Tan Valley became Arizona’s newest town on July 1, 2026. That changes who you work with. Zoning clearance comes from the Town, and starting November 1, 2026, so do building plan review, permits and inspections. Pinal County no longer handles them inside town limits. Plans submitted to the county before November 1 finish with the county.
Because the town’s code is so new, casita rules are something we check project by project against the current ordinance. If you’re planning a casita in San Tan Valley, start the conversation early. Our San Tan Valley page explains the transition.
Apache Junction: rentable casitas on bigger lots
Apache Junction has fewer than 75,000 residents, so HB 2720’s mandate doesn’t apply, but the city updated its own rules in November 2024. A single-family lot can have one accessory dwelling of up to 1,000 square feet or 75% of the main home’s size, whichever is smaller, up to 25 feet tall, and long-term rentals are allowed.
Add in the acreage and horse property on the east side of the Valley, and Apache Junction is one of the best places around to build a casita with room to spare. More on our Apache Junction page.
What to check before you design a casita
Whatever city you’re in, these five questions decide what’s possible:
- Which rules apply? State law, your city’s own ordinance, or both.
- What does your HOA allow? Get the current design guidelines, not the ones from when you bought.
- Where do utilities come from? Water, sewer or septic, and electric capacity all affect cost and layout.
- How will you use it? Family, guests or a long-term rental changes the kitchen, entry and privacy decisions.
- Should it match the main house? A casita that matches your home’s roofline and finishes adds more value and usually sails through HOA review.
How we build casitas
We design and build detached casitas and guest houses across the East Valley, and we handle the part most people dread: sorting out which rules apply to your lot, then taking the plans through permits. Take a look at our casitas and guest houses service, or read how our process works from first meeting to final walkthrough.
Rules change, and every lot is different, so treat this as a starting point rather than approval for a specific property. When you’re ready, we’ll check your lot and tell you plainly what you can build.