Can you build a casita or ADU on a home in Scottsdale?

Possibly, because Arizona law requires larger cities to allow accessory dwelling units (ADUs) on single-family lots, and the City of Scottsdale has its own ADU rules, but whether your particular lot qualifies is something only the city's planning staff and your HOA can tell you. The answer can change from one address to the next, because location, lot size, the existing home and community rules all play a part. Nobody can promise you in advance that a lot allows one.

I'm Jen Keene, a REALTOR® with eXp Luxury in Scottsdale, AZ, and I'm the agent people call at every stage of their life. What follows is general information on what the state and the city say as of November 9, 2026, and it is not legal advice. Rules in this area have been changing, so check the pages I name against what is current.

Under the state's casita law, which Governor Hobbs signed in 2024, cities with more than 75,000 residents have to allow at least one attached and one detached ADU on a lot where a single-family home is allowed. Scottsdale is in that group. The statute is A.R.S. 9-461.18, and a follow-up bill, HB 2928, was signed in 2025 and changed some of the details, including the airport areas I cover below.

The statute also limits what a city can ask for. A city can't require a rear or side setback of more than five feet for an ADU or require extra parking for it, and it can't set the size limit lower than the smaller of 1,000 square feet or 75 percent of the main home. Lots of an acre or more can have one more detached unit if at least one ADU on the lot is a restricted-affordable unit. The law applies to the city's rules. It does not say anything that overrides a private agreement such as an HOA's covenants, and the statute says a city can't make an ADU permit depend on one.

The Scottsdale Area Association of REALTORS® reported in February 2026 that a bill to change the casita law, HB 4028, failed in a House committee by one vote. That is one source for that bill, so confirm with the legislature's site whether anything new has passed since.

The Scottsdale City Council adopted Ordinance 4687 on September 30, 2025, to bring the city's zoning ordinance in line with the state law, according to the city's ADU page, which was last updated May 21, 2026. The city says an ADU is a smaller, self-contained home on the same lot as a main single-family home, with its own kitchen and sanitary facilities, and that it may be rented separately from the main home. The lot has to be a single-family lot that already has a main home on it.

The city's page lists one attached and one detached ADU per property, with a third detached unit possible on a lot of an acre or more if one of the ADUs is an affordable unit. It says the first ADU can be as large as the smaller of 1,000 square feet or 75 percent of the main home, and it lists other standards for separate entrances, utilities, addresses, outdoor space and where a detached unit can sit on the lot. The page also lists smaller limits for additional units, and the city can change them, so read them there.

The city's own news release says it opposed the state bill and that the state limits what it can require, including fire sprinklers, on-site parking and setbacks greater than five feet. So when you read a summary of Scottsdale's ADU rules, check its date against the city's page.

The City of Scottsdale treats them as two separate things in its zoning ordinance. A guest house is a detached building for the guests of the people living in the main home, and the city's guest house page says it is not a dwelling unit or an ADU. The city says a guest house shares the main home's utilities and cannot be rented separately from the main home, and that all of the guest houses on a lot together can add up to no more than half the size of the main home.

An ADU, by the city's definition, has its own kitchen and sanitary facilities, can be rented separately, needs separately metered electric service and its own entrance and address, and can't be sold separately from the main home. The city's guest house page does not say whether a guest house may have a kitchen, so if your plan for a casita includes a full kitchen, ask the city's Planning and Development Services in writing what category it would fall under. The city's ADU page also says an ADU needs administrative approval before the permit stage, while a guest house goes straight to permit submittal.

If you are looking at a home that already has one, my post on buying a home with a guest house in Scottsdale goes through how to check what the city has on record.

Yes, the airports are the clearest example. Both the state statute and the city's page say the requirements don't apply to land near certain airports. The city's page says the 2024 state law restricted ADUs near airports, that HB 2928 made those restricted areas smaller, and that parts of Scottsdale are still within the operating vicinity of Phoenix Sky Harbor International Airport and Scottsdale Airport. ABC15 reported that state lawmakers questioned how widely Scottsdale applied the airport exemption when it first adopted its rules in late 2024.

I can't tell you from here whether a particular address is inside one of those areas, and I won't guess. Ask the city before you spend money on plans, and ask at the same time whether any other overlay or protected open space applies to your lot.

They can apply to you even when the city and the state allow the ADU. The city's October 2025 news release says homeowner association rules may be more restrictive than the city ordinance, and the Your Valley newspaper reported the same line from the council meeting. The state statute says a city can't require a private covenant for an ADU, and it also says it does not prohibit private covenants between private parties.

So the city's approval and your community's rules are two separate questions. Ask your HOA for the declaration (CC&Rs), the design guidelines and any architectural review process, and read them for casita, guest house, outbuilding and rental language. If your home is in a gated or master-planned community, here are my posts on gated communities and HOAs in Scottsdale and HOA rules and regulations in Arizona. Deed restrictions recorded on your property can also matter, and a title company or an attorney can tell you what is recorded on yours.

According to the city's ADU page, you start with an online pre-application, ideally with a site plan, elevations and utility information, and the city schedules a pre-application meeting with staff. If the owner then submits a formal application for administrative review, and it is approved, the next step is construction documents for permit review. The page lists a phone number for Planning and Development Services, 480-312-3111, and the city's ADU FAQ describes the same three stages.

I won't give you fees or a schedule, because I don't have a source for either that I trust, and it is a question for the city. The same is true of what a project will cost you to build. Permits matter for the building work as well, and I cover what the city says needs one in my post on permits for a remodel in Scottsdale. If you are thinking about renting the unit short term, the rules are separate, and they're in my post on short-term rental rules in Scottsdale.

• The city: Is this lot eligible for an ADU, is it inside an airport area, and what is the current size limit? Is a guest house with a kitchen treated as an ADU?
• The HOA: Do the declaration or the design guidelines say anything about casitas, guest houses or a second home on the lot?
• The seller, if you are buying: Is there a permit and final sign-off for the unit that is already there, and does the city have it on record as a guest house or an ADU?
• Your lender: How will the appraiser treat the unit, and does it count toward the home's square footage?
• A title company or attorney: What is recorded on the property, and what does it mean for your plan?

If you are looking at a home and a casita is part of why, tell me the address. I'll help you work out which questions go to the city and which go to the HOA, and I'll put them in writing with you. Get in touch or call me at (480) 203-6605.