Skip to content

ADU Conversion in Phoenix: 2026 Guide

Phoenix calls them casitas, and the rules changed sharply in 2024. Arizona Revised Statutes section 9-461.18, passed in 2023, preempts municipalities from outright banning ADUs and overrides HOA prohibitions on the structures. The City of Phoenix codified its local implementation in Ordinance G-7115, effective 2024, which now sits inside Phoenix Zoning Ordinance section 608. Baily walks you through the actual eligibility test, the 1,000 square foot cap, the parking exemptions near transit, and where Phoenix PDD plan-review tends to slow projects down.

Authored by Netanel Presman — CSLB RMO #1105249 · Updated 2026-04-26

Regulatory framework in Phoenix

Arizona's statewide ADU statute, ARS 9-461.18, took effect in 2023 and forced cities of more than 75,000 residents to allow at least one accessory dwelling unit on lots that already permit a single-family home. The statute also preempts HOA covenants and restrictions that would otherwise prohibit ADUs, which had been the most common blocker on master-planned Phoenix subdivisions. Cities retain the right to set design standards, but they cannot ban ADUs outright, cannot impose owner-occupancy requirements, and cannot require off-street parking for ADUs within a half-mile of major transit stops.

Phoenix implemented the state law through Ordinance G-7115, now codified at Phoenix Zoning Ordinance section 608. Attached and detached casitas are allowed up to 1,000 square feet or 75 percent of the principal dwelling, whichever is less. There is no owner-occupancy requirement and no minimum lot size beyond what the underlying zoning already establishes. Setbacks generally match the principal dwelling's side and rear setbacks, with reductions available for detached units. Permit review runs through Phoenix PDD's standard residential queue. The HOA preemption from ARS 9-461.18 is what most homeowners are surprised by: even if your CC&Rs explicitly forbid ADUs, the state statute overrides that prohibition for new builds.

Costs and timelines (2026)

A detached casita in Phoenix typically runs $150,000 to $400,000 all-in, with most middle-market projects landing between $200,000 and $300,000 for a finished 700 to 900 square foot unit. Garage conversions, where you keep the existing slab and roof structure, come in at $80,000 to $220,000 depending on whether the garage was originally permitted as living-adjacent space. Soft costs, including architectural plans, structural engineering, mechanical and electrical design, and Phoenix PDD plan-check fees, generally add 8 to 14 percent on top. Phoenix's residential plan review typically takes four to eight weeks for a complete submittal, faster than coastal-state norms.

Phoenix does not currently waive impact fees for casitas, but the impact fee structure for a unit under 1,000 square feet is materially lower than for a full second dwelling. Arizona has no statewide ADU grant equivalent to California's CalHFA program. The financial advantage in Phoenix is mostly on the timeline side: PDD's review windows are shorter, and the lack of an owner-occupancy requirement means you can finance the casita as a rental from day one. The state HOA preemption also unlocks a class of master-planned-community lots that would have been off-limits in 2022. Baily can pull your parcel's zoning class and HOA status before you scope.

Four pitfalls specific to Phoenix

  1. 1. Assuming your HOA still has authority to block. Many Phoenix homeowners assume their HOA's CC&R prohibition on ADUs is binding. ARS 9-461.18 explicitly preempts those provisions for ADUs that meet the statutory criteria. The HOA can still impose reasonable design standards, but cannot ban the structure outright. Owners who never check the statute can spend months in HOA appeals when they should have gone directly to Phoenix PDD.
  2. 2. Misjudging the 75 percent cap. The Phoenix casita cap is 1,000 square feet or 75 percent of the principal dwelling, whichever is less. On smaller starter homes around 1,200 square feet, that means your casita is capped at 900 square feet, not 1,000. Designing to the higher number and discovering the actual cap during plan check forces a redesign and a resubmittal. Verify the principal-dwelling square footage off the assessor record before you scope.
  3. 3. Skipping the half-mile transit check. Phoenix removes the off-street parking requirement for casitas within a half-mile of major transit stops, including light rail and primary bus corridors. Outside that radius, parking is required. Owners who assume the no-parking rule applies sitewide will end up redesigning to add a parking pad. Pull the Valley Metro transit-stop map and measure the actual half-mile radius from your parcel before scoping.
  4. 4. Treating short-term rental rules as ADU rules. Arizona's separate short-term rental statute and Phoenix's STR licensing rules are not the same as casita rules. A casita built under section 608 is permitted as a dwelling unit, not as an STR. If you intend to operate the unit as a short-term rental, you have a second layer of permitting and licensing on top of the casita permit, including STR registration with the city.

Five-item checklist before you sign

Frequently asked

What is the Phoenix Casita Ordinance and does my lot qualify?

Phoenix Ordinance G-7115, effective 2024 and now codified at Phoenix Zoning Ordinance section 608, allows attached and detached casitas on lots that already permit a single-family home. The casita can be up to 1,000 square feet or 75 percent of the principal dwelling, whichever is less, and there is no owner-occupancy requirement. Most single-family-zoned parcels in Phoenix qualify automatically, though hillside, historic, and floodplain overlays can layer additional requirements. The fastest way to confirm is to pull the parcel's zoning class and overlay status from Phoenix PDD's online portal.

Does ARS 9-461.18 override my Phoenix HOA's ADU prohibition?

Yes, with limits. ARS 9-461.18, passed in 2023, preempts HOA covenants that prohibit accessory dwelling units in cities of more than 75,000 residents, which includes Phoenix. The HOA cannot ban the structure outright. The HOA can still impose reasonable design and architectural standards, similar to the standards it imposes on principal dwellings, but it cannot use those standards as a de facto ban. If your HOA refuses to acknowledge a casita application, the state statute is the controlling authority and you have a path through Phoenix PDD regardless.

What is the minimum lot size for a Phoenix casita?

Phoenix does not impose a separate minimum lot size for casitas beyond what the underlying zoning already establishes for the principal dwelling. If your lot already qualifies for a single-family home under its zoning class, it qualifies for a casita. The constraint that bites first is usually setback math: rear and side setbacks, lot coverage limits, and lot-coverage-with-accessory-structure caps determine how big a casita the parcel can physically accommodate. A 6,000 square foot lot can typically support a 700 to 900 square foot detached casita once setbacks are honored.

Related pages

Still have questions?

Ask Baily — pre-seeded for this topic.

Loading chat…