Everything homeowners ask about building an ADU in Phoenix — answered with 2026 data.
Yes, ADUs are allowed in Every residential district, on a lot with no more than one single-family detached house: S-1, S-2, RE-43, RE-24 and R1-14 (ZO Sections 603-607) and RE-35, R1-18, R1-10, R1-8, R1-6, R-2, R-3, R-3A, R-4, R-4A, R-5 and residential PADs (ZO 608.E.2, use table condition pc2). Lots with a duplex, triplex, single-family attached or multifamily units get no ADU. Look up your district on the city's My Community Map in Phoenix, AZ. The maximum size for a detached ADU is 75% of the primary home's gross floor area (interior habitable area), and no more than 1,000 sq ft on a lot of 10,000 sq ft or less; on a lot over 10,000 sq ft, the lesser of 3,000 sq ft or 10% of net lot area (ZO 706.A.8). A garage, carport or attached shade structure built as part of a detached ADU does not count toward its floor area but does count toward lot coverage. Attached ADUs can be up to Same formula: 75% of the primary home's gross floor area, capped at 1,000 sq ft. Phoenix has an ADU-friendliness score of 7/10. Check our full Phoenix ADU rules page for complete zoning details.
ADU construction in Phoenix typically costs $150,000-$280,000. The cost per square foot averages $200-$350. Garage conversions are more affordable at $80,000-$150,000, while prefab ADUs cost $155,000-$300,000. Permit fees add Valuation-based (PDD Fee Schedule, Ordinance G-7465, effective January 20, 2026, Table A): permit fee $703 on the first $50,000 plus $9 per $1,000 up to $200,000, then $2,053 plus $9 per $1,000; residential plan review is 80% of the permit fee when valuation exceeds $50,000 (100%, minimum $195, at or below); plot plan review $98; each extra utility meter $98. Examples: a $150,000 valuation is about $1,603 permit + $1,282 plan review + $98 = $2,983; $250,000 is about $2,503 + $2,002 + $98 = $4,603. Valuation is the higher of the city's square-foot valuation table or your contract price. Re-inspections after the first are $195 each to your budget. See our detailed Phoenix ADU cost guide.
Detached ADUs in Phoenix can be up to 75% of the primary home's gross floor area. Attached ADUs are limited to Same formula: 75% of the primary home's gross floor area, capped at 1,000 sq ft. Junior ADUs (JADUs) have a cap of Phoenix has no junior ADU category. A self-contained unit carved out of the existing house (or a garage attached to it) is simply the one attached ADU allowed per lot and follows the same 75% / 1,000 sq ft limits. Maximum height is Detached ADU inside a required rear or side yard: 15 ft, or more with a use permit under Section 307 (706.A.4.c). A detached ADU that meets the house's own setbacks may use the district height, 2 stories and 30 ft in R1-6 and R1-8 (Tables 612.A and 613.A). An attached ADU follows the house's height and setbacks, and may project into the rear or side yard only if it stays under 15 ft, 3 ft off the rear line and 5 ft off a side line (701.A.3.a(2)(d)). You are allowed up to 2 ADUs per lot with one single-family detached home on a qualifying lot.
Rear setback: 3 ft from an interior rear lot line for a detached ADU; 0 ft along a fully dedicated alley (706.A.4.b). Attached ADU: the house's rear setback, or a projection to 3 ft if under 15 ft tall. State law caps any ADU rear or side setback at 5 ft (ARS 9-461.18.B.6). Side setback: 3 ft from an interior side lot line and 5 ft from a street-side lot line for a detached ADU (706.A.4.b). Attached ADU: the house's side setback, or a projection to 5 ft if under 15 ft tall. Front setback: The underlying district's front setback applies (706.A.4.b(4)); in conventional R1-6 that is 10 ft for the building and 18 ft from the back of sidewalk for a front-loaded garage (Table 613.A). A detached ADU may not sit between the house and the front lot line without a use permit (706.A.5). Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
No additional parking may be required for an ADU (ARS 9-461.18.B.3; city ADU process guide TRT/DOC/00192 FAQ). If you convert the garage or carport, the city's ADU Beginner's Guide says the house's off-street parking must be re-established elsewhere on the lot on a dustproof surface, outside the front setback. Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Not required. Either the house or the ADU may be rented long-term (90-day or month-to-month leases) with no family or employment relationship (ARS 9-461.18.B.1-2). Only exception: to hold a short-term rental permit on a property whose ADU was finaled on or after September 14, 2024, the owner must attest and prove they live on the property (City Code Ch. 10 Art. XVI, effective April 4, 2026). Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Phoenix is typically Not published as a fixed ADU figure. Planning & Development posts a monthly Plan Review Turnaround Times report (goal vs. actual, by plan type) on its Reports, Data and Turnaround Times page; plan on at least one correction cycle. Phoenix builders' 2026 guides quote 6-12 months from design start to move-in for a detached casita and 4-6 months for a garage conversion. Plan check: Full residential plan review (no over-the-counter path for ADUs). Submit a plot plan with site-planning approval, floor plans, elevations, structural and energy-code documents per the Residential Plan Submittal Checklist, and note fire-rating requirements per IRC R302; no grading-and-drainage plan is required for an attached or detached ADU (TRT/DOC/00192). Extra reviews apply on hillside lots (slope over 1:10), historic properties and floodplain lots. State law bars the city from requiring a fire sprinkler or commercial-code compliance in an ADU (ARS 9-461.18.D). Pre-approved plans availability: In progress. The city's ADU Standard Plan Library, built from the 2024 City of Phoenix / AIA Phoenix Metro design competition, listed four detached designs marked 'in review' on the city ADU page in May 2026; approved plans are free to Phoenix residents, must be used without modification and still need a plot/site plan. State law (ARS 9-461.20, from SB 1529 of 2025) requires Phoenix to offer at least three pre-approved ADU plans at 200, 600 and 1,000 sq ft from July 1, 2026 and to accept outside plan submissions; check the city ADU page for the current list.
Average ADU rental income in Phoenix: 1-bedroom units rent for $1,150-$1,500/month, 2-bedroom units for $1,500-$1,750/month. Short-term rentals: Yes, with a city short-term rental permit for each unit (City Code Ch. 10 Art. XVI; TPT license, $500,000 liability insurance, neighbor notice). Expected ROI: Roughly 6-11% gross rental yield on a $150,000-$280,000 detached build at $1,300-$1,700/mo (before taxes, vacancy, insurance and financing).
The minimum lot size for an ADU in Phoenix is No minimum lot size for an ADU; any lot that legally holds one single-family detached home qualifies. Lot size instead sets the cap: 1,000 sq ft on lots up to 10,000 sq ft, 3,000 sq ft or 10% of net lot area above that (a 12,000 sq ft lot allows 1,200 sq ft). Lot coverage also binds: R1-6 and R1-8 allow 50% plus 10% for an ADU or attached shade structure, 60% total (Tables 612.A, 613.A); RE-43, RE-24, RE-35 and R1-14 allow 40% when every structure is one story. This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Phoenix, a garage conversion typically costs $80,000-$150,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.
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