Building a casita in Phoenix: the rules, fees and the math

Phoenix is covered by Arizona's 2024 casita law, so an attached and a detached unit are allowed by right on a single-family lot with no owner-occupancy or extra parking requirement. Below is how Phoenix wrote that into its own code, read from the city's ordinance on October 7, 2026, and what the resale market here does to the decision.

The rules in Phoenix

Ordinance / code	Ordinance G-7317 (Z-TA-2-24); Zoning Ordinance Section 706.A (ADU standards) and 608.E.2
Adopted	November 20, 2024
Units allowed	Two per single-family lot: one attached and one detached. A third on lots of an acre or more if one unit is deed-restricted affordable. None on lots that already have multifamily units.
Maximum size	75% of the main home's gross floor area, up to 1,000 sq ft on lots of 10,000 sq ft or less. A garage, carport or shade structure built as part of a detached unit does not count toward the unit's size.
Larger lots	Lots over 10,000 sq ft net: up to 3,000 sq ft or 10% of the lot, whichever is less (still capped at 75% of the main home).
Setbacks	Detached unit: 3 ft from an interior side or rear line, 5 ft from a street side line, 0 ft along a dedicated alley. It may sit in the required rear or side yard but not between the house and the street without a use permit. Attached unit: the same setbacks as the house.
Height	15 ft when placed inside the required rear or side yard (more with a use permit); otherwise the height allowed for the house.
Parking	None required. If a garage or carport is converted, the parking it provided has to be re-created elsewhere on the lot, not in the front setback.
Renting it out	Both units may be rented long-term and the owner does not have to live on the property. The city's ADU guide says units may also be used as short-term rentals with the city's short-term rental registration; state law lets Phoenix require the owner on site for a unit finished after September 14, 2024.
Permit process	Site planning approval, then residential building plan review. No separate registration. A separate address for the unit is available on request from Addressing Services.
Plan review time	Published initial plan review goals: 30 days for new home plans (37-day average at the last report), 20 days for one-level remodels and additions up to 2,000 sq ft.

Phoenix runs a free ADU Standard Plan Library of pre-approved detached designs for city residents, with more plans in review on the day we read the page. Units do not count toward density, but lot coverage limits still apply. Check HOA covenants separately. One older city handout (TRT 00192, dated January 2024) still shows the pre-2024 one-unit, no-short-term-rental language and is out of date.

Source: City of Phoenix: Accessory Dwelling Units; phoenix.municipal.codes; phoenix.municipal.codes; web-prod.phoenix.gov; web-prod.phoenix.gov; phoenix.gov. Read October 7, 2026.

Fees in Phoenix

Permit and plan review. Standard valuation-based building permit and plan review fees; the city publishes no ADU-specific line. Our earlier estimate of about $2,983 in permit, plan review and plot-plan fees on a $150,000 valuation comes from the January 2026 fee schedule.
Impact fees. Charged only in the designated growth areas (Northwest, Deer Valley, Northeast, Paradise Ridge, Estrella, Laveen, Ahwatukee) under the June 23, 2025 schedule; $0 in the established "Balance of City". There is no ADU line, so the single-family rate for the area applies until the 2026 state cap is written into the schedule.
Utility connection and capacity. One combined water service connection may serve the house and the unit, and a separate sewer tap is allowed only through a technical appeal (Water Services ADU policy, October 2023). Capacity charges apply only where a new meter is installed; amounts are set by meter size.

In June 2026 the state capped the development (impact) fees a city may charge an ADU for services other than water and sewer at the lesser of 25% of the single-family fee or the unit's proportionate share, and limited water and sewer fees to the unit's added demand (HB 2946, signed June 5, 2026). Most cities had not yet re-published schedules when we read them; Glendale's 25% ADU line is the first we found. Expect ADU impact fees to fall toward that cap. Governor's announcement.

What the state law guarantees here

Whatever the local code says, in Phoenix these points come from A.R.S. § 9-461.18 and the city cannot be stricter:

At least one attached and one detached ADU on any lot with a single-family home, as a permitted use (no public hearing, no variance)
A unit up to 75% of the main home's gross floor area or 1,000 sq ft, whichever is smaller (cities may allow larger)
A third, detached unit on lots of one acre or more if one unit is deed-restricted affordable
Separate long-term rental of either the house or the ADU (leases of 90 days or more, or month to month)

The math in Phoenix

Redfin's median sale price in Phoenix is $285 per square foot. A new casita builds for about $265 to $280 per finished foot and a garage conversion for about $120. That puts Phoenix in the "Clears at full credit" tier: one square foot of new casita, at the typical $272 build cost, comes out −$58 at a 75% appraiser credit and +$13 at full credit. A conversion clears at either credit.

Phoenix is too big for one number. By neighborhood, from Redfin's readings:

Area	Resale $/sq ft	Tier
Arcadia	$578	Clears even at a discounted appraisal
Downtown Phoenix	$506	Clears even at a discounted appraisal
Biltmore	$492	Clears even at a discounted appraisal
Camelback East	$415	Clears even at a discounted appraisal
North Central Phoenix	$412	Clears even at a discounted appraisal
Coronado	$385	Clears even at a discounted appraisal
Melrose (Paradise)	$376	Clears even at a discounted appraisal
Moon Valley	$360	Clears at full credit
Paradise Valley Village	$340	Clears at full credit
Desert View	$328	Clears at full credit
Encanto	$327	Clears at full credit
Central Phoenix	$301	Clears at full credit
Ahwatukee Foothills	$283	Clears at full credit
Sunnyslope	$276	At the line
North Gateway (Norterra)	$269	At the line
Deer Valley	$265	At the line
Willo	$251	Conversion territory
Alhambra	$246	Conversion territory
Laveen	$238	Conversion territory
Garfield	$236	Conversion territory
South Mountain	$233	Conversion territory
Maryvale	$221	Conversion territory
Estrella	$214	Conversion territory

The target areas page explains the tiers and the math page has the calculator. Rent is the other half: see rental math.

Owners and investors in Phoenix

Homeowners get a by-right unit for family, guests or long-term rent, with the same appraisal and lender rules as anywhere in the Valley.
Investors can treat the casita as the piece that moves a house out of its neighborhood's price band at resale, as our two Maryvale sales show on the case studies, and as monthly income in the meantime. Phoenix's rental rules above say whether both units can be let separately.
Either way the lot decides: setbacks, utilities, sewer depth and easements. Request a property review and we confirm the current Phoenix rules for your address.

Other city pages: Mesa, Chandler, Gilbert, Scottsdale, Tempe, Glendale, Peoria, Surprise, Goodyear, Buckeye.

Rules were read from Phoenix's published ordinance and planning material on October 7, 2026 and summarized in plain terms; this is not legal advice. Cities amend codes, and some parcels sit in zones the state law excludes (near military airports, in airport noise zones, on tribal land). We confirm the rules that apply to your parcel during the property review.

Request a property review

Find out what your property can hold.

Send the address and your goal. Anthony Alexander Lopez or Juan M Lopez Solano will review zoning, setbacks and utilities and reach out within one business day. No obligation, and no city approval implied: it is our professional read of your lot.

Prefer to talk? (602) 386-6623 · See completed projects