Compare ADU zoning rules across 14 Arizona cities. Average ADU score: 6.4/10.
Gathered from the 14 cities below, with the bill or ordinance each one names. Statewide measures are listed once with the cities they reached, rather than repeated for each.
Statewide law sets a floor; the numbers that decide your project are local. Here is the spread across the 14 Arizona cities covered here, taken from each city's own ordinance rather than a state summary.
| Question | Across Arizona |
|---|---|
| Are ADUs permitted? | 13 of 14 permit them, and 1 do not. |
| Detached size cap | Median 1,000 sq ft, from 500 to 1,000 sq ft across the 13 cities publishing a numeric cap. |
| Owner-occupancy | Required in none of them. |
| Build cost | $125,000 to $600,000 depending on city and unit type. |
| Easiest and hardest here | Tempe scores 8/10; Paradise Valley scores 2/10. |
Recomputed whenever a city page changes, so this and the city pages below cannot disagree.
| City | Max Size | Setbacks | Permit Fees | Build Cost | 1BR Rent | Score |
|---|---|---|---|---|---|---|
| Avondale | The lesser of 75% of the gross floor area of the existing single-family dwelling or 1,000 sq ft (§28-33(a)(3)(A)); for this section gross floor area means the interior habitable area of the house or the ADU (§28-33(a)(3)(A)(I)), not the exterior-wall measure in §28-15. No more than two bedrooms (§28-33(a)(3)(G)). A detached ADU counts toward the district building coverage cap: 45% in R1-8 to R1-5, 40% R1-10, 20% R1-15, 30% RR-18, 15% AG/RR-43/R1-35 (§28-33(a)(3)(E); §28-35.A; §28-133(f)) | 5 ft from the property line (§28-33(a)(3)(D)(I)), against a house rear setback of 15-40 ft by district; state law caps what the city may require at 5 ft (A.R.S. §9-461.18(B)(6)) | FY2027 schedule (eff. 9/1/2026): permit $1,247 + $8 per $1,000 of valuation over $100,000, plan review 65% of that, $102 application fee, $158 C of O — about $2,400 for a 600 sq ft casita valued near $106,000 and $3,320 at 1,000 sq ft (~$176,000). Impact fees are separate | $150,000-$280,000 | $1,400-$1,700/mo | 6/10 |
| Buckeye | 75% of the gross floor area of the single-family dwelling on the same lot (§3.3.4.A.4) — a ratio with no separate square-footage ceiling, so a 1,500-square-foot ADU fits behind a 2,000-square-foot house. The state floor requires only the lesser of 75% or 1,000 square feet (A.R.S. §9-461.18(A)(3)), so Buckeye is more generous for houses over about 1,333 square feet. Gross floor area runs to the exterior faces of exterior walls, less underground parking, uncovered steps and balconies (§10.3) | 5 feet from the property line — the ADU exception to the district's principal-dwelling rear setback (§3.3.4.A.2), which otherwise runs 40 ft in AG, 30 ft in R1-43 and R1-18, 25 ft in R1-10, 20 ft in R1-6, 10 ft in R1-3, 8 ft in R1-1 and 15 ft in MF-1 (Table 4.1-1); state law bars the city from requiring more than 5 feet (A.R.S. §9-461.18(B)(6)) | $4,100-$5,600 in permit and plan-review fees for a 600-1,000 sq ft casita (Development User Fee Schedule, Res. 38-26, effective May 21, 2026: Table 1-A permit fee on the ICC valuation of $175.92/sq ft, plus 65% plan review and a $54 plot-plan review) | $150,000-$280,000 | $1,350-$1,750/mo | 7/10 |
| Chandler | 75% of the single-family dwelling's gross floor area (interior habitable area) or 1,000 sq ft, whichever is less | 5 feet minimum (uninhabitable space attached to an ADU, e.g. a garage, must meet full district setbacks) | Valuation-based per Chandler fee schedule using ICC Building Valuation Data (minimum permit fee $60); third-party guides estimate roughly 1.5-2% of construction value plus plan review — confirm exact amounts with Chandler Development Services | $125,000-$250,000 | $1,350-$1,700/mo | 6/10 |
| Gilbert | 75% of the primary home's gross floor area (interior habitable area), measured by LDC Section 2 'Gross Floor Area'. Up to 1,000 sq ft is by right; from 1,001 sq ft up to the 75% cap the unit needs a $1,000 Administrative Use Permit and must be inside the building envelope (LDC 5.2.3.4.c, 5.2.3.A-B). State floor: the lesser of 75% or 1,000 sq ft must be permitted (ARS 9-461.18.A.3). | 5 ft minimum for an ADU up to 10 ft tall; add 1 ft for every foot of height over 10 ft (a 13-ft unit needs 8 ft). Units of 1,000 sq ft or less may sit inside the rear setback area; units over 1,000 sq ft must stay within the building envelope, i.e. the district rear setback of 20-40 ft (LDC 5.2.3.A.1-2, 5.2.3.B.2). State cap: 5 ft (ARS 9-461.18.B.6). | Valuation-based: a $150,000 valuation is $1,145 permit plus $744.25 plan review (65% of the permit fee), about $1,890; add a $1,000 Administrative Use Permit if over 1,000 sq ft (Development Services Fee Schedule, Res. 4563 eff. July 1, 2025, revised Sept 15, 2026). | $150,000-$280,000 | $1,500-$1,800/mo | 6/10 |
| Glendale | Up to the gross floor area of the existing house, but never more than 1,000 sq ft (UDC §35.3.204.A.16; Ord. O25-45 changed 'square footage' to 'gross floor area'). Gross floor area is measured within the exterior walls (§35.8.004). This beats the state floor of the lesser of 1,000 sq ft or 75% of the house (A.R.S. §9-461.18(A)(3)), so a 1,000 sq ft casita is legal behind a 1,000 sq ft house | No less than 5 ft from the rear property line (UDC §35.3.204.A.11.a); the house itself needs 15–25 ft in the R1 districts, so the ADU may sit closer than the house. State law caps what the city may require at 5 ft (A.R.S. §9-461.18(B)(6)). A detached unit must also stand behind the front plane of the house and 6 ft (fire-rated) or 10 ft from it (§35.3.203.B.1, B.3) | $2,500-$3,400 in review and permit fees for a 500-1,000 sq ft ADU (May 2019 fee schedule Table 3A at the city's $120.75/sq ft valuation; city's 1,000 sq ft estimate: zoning clearance $144, plan review $1,052.90, permit $1,403.86, right-of-way permit $443.60) — plus the $775.25 impact fee | $150,000-$280,000 | $1,200-$1,750/mo | 7/10 |
| Goodyear | The lesser of 75% of the gross floor area of the principal single-family dwelling or 1,000 sq ft (§3.12.3.A.8). Article 8 measures gross floor area from the exterior walls, excluding only underground parking, uncovered steps, portals and exterior balconies; the state statute's own definition is interior habitable area (A.R.S. §9-461.18(I)(2)) — ask the planner which figure they apply to your house | 5 ft (§3.12.3.A.5) — the ceiling state law allows (A.R.S. §9-461.18(B)(6)). The general accessory-building rule sends any building with sleeping facilities to the principal-building setbacks (§3.12.2.I.5 — 15 to 30 ft rear in the R1 districts), but §3.12.3 is the ADU-specific provision and matches the state cap; ask the planner to confirm in writing. Setbacks are measured to the roof overhang, not the wall (§3.12.2.J) | 'Detached Casita or Guest House' (Fee Schedule p.11): permit per Valuation Table 1-A ($1,416 plus $8 per $1,000 over $100,000), plan review 65% of the permit, $86 planning and zoning, $102 application — about $3,184 on a $150,000 valuation, $3,844 on $200,000. Paid at issuance in Accela | $150,000-$280,000 | $1,450-$1,800/mo | 7/10 |
| Mesa | 75% of the primary residence's interior habitable area or 1,000 sq ft, whichever is less (11-31-3(C)); a 1,200 sq ft house allows up to 900 sq ft, a house of 1,334 sq ft or more allows the full 1,000. Since Ord. 5950 (Aug 2025) the ADU no longer counts toward the cap on combined detached accessory floor area in 11-30-17(A)(4). District lot-coverage and building-coverage limits still apply (11-31-3(E)). | 5 ft minimum for a new attached or detached ADU (11-31-3(D)(1)(a), as rewritten by Ord. 5950, effective Aug 2025). An existing detached building that meets the 11-30-17 accessory-building setbacks, or is legal non-conforming, can be converted to an ADU with no added setback; an expansion may follow the existing non-conforming line if it does not worsen it. Since Ord. 6025 a detached ADU must also sit at least 5 ft from the house, other ADUs and accessory buildings. | Valuation-based (Development Services Schedule of Fees, July 2026): $500 plus $6 per $1,000 of valuation over $25,000, up to $200,000; then $1,550 plus $9 per $1,000. A $150,000 ADU pays about $1,250 and a $250,000 unit about $2,000, plan review and trade permits included. | $150,000-$280,000 | $1,250-$1,500/mo | 7/10 |
| Paradise Valley | No square-foot cap. Two limits bind: all accessory buildings and structures together may not occupy more than one-half of the main building's ground area (§1005.A; Policy #53: first floor incl. covered patios and attached garage, overhangs excluded; Policy #59: wall face to wall face plus roofed patios and ramadas); and the guest house counts toward the lot's 25% floor area ratio in R-175 through R-18A, "inclusive of all areas under roof" (Table 1001-A1; FAR Certification handout rev. 6-29-26) | 20 ft in R-175 and R-43; 10 ft in R-35, R-35A, R-18 and R-18A; 7 ft in R-10 — rising to 40 ft (35 ft in R-18A, 20 ft in R-10) where the rear yard fronts a street (Table 1001B). Nothing in state law caps these: the 5-ft ceiling in A.R.S. §9-461.18(B)(6) binds only municipalities over 75,000 people. In R-10 an owner may instead use the setback on the recorded plat or as it existed at annexation, with documentation (Policy #50, rev. 9/20/17) | Valuation-based (minimum $225 per livable sq ft): $1,436.92 plus $5.40 per $1,000 over $150,000, plus 65% of that for plan review (Master Fee Schedule, App. B, eff. 7/1/2025). About $2,000-$3,500 in Town fees for a 500-1,200 sq ft guest house | $300,000-$600,000 | $1,800-$1,950/mo | 2/10 |
| Peoria | The lesser of 75% of the gross floor area of the existing single-family dwelling or 1,000 sq ft (Peoria City Code §21-316.C.2); 'gross floor area' means interior habitable area (§21-316.B). The ADU must be smaller than the house (§21-316.B definition) and counts toward the district's lot-coverage cap (§21-316.D.3) | 5 ft from the property line (Peoria City Code §21-316.D.2.a) — versus the 15-ft rear setback a house must keep in R1-18 through R1-6, 20 ft in R1-35 and 30 ft in R1-43 (§21-420.A). State law caps the ADU rear setback a city may require at 5 ft (A.R.S. §9-461.18(B)(6)) | Valuation-based (Fee Table 27-6, Ord. 2025-28, 11-4-25): $1,045.25 for the first $100,000 of construction value plus $5.60 per $1,000 above it, plus plan check at 65% of the permit fee — about $2,190 on a $150,000 casita, before impact fees | $150,000-$280,000 | $1,400-$1,900/mo | 7/10 |
| Phoenix | 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 | 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) | 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 | $150,000-$280,000 | $1,150-$1,500/mo | 7/10 |
| Scottsdale | First ADU on the lot: 1,000 sq ft or 75% of the existing main house, whichever is less (Sec. 7.900; ARS 9-461.18 measures interior habitable area). The second and any third ADU: 500 sq ft each. Every ADU needs a private outdoor living space at least 5 ft deep and 50 sq ft, and no more than 6 adults may live in the house and ADUs combined. | 5 ft for a detached ADU built in the rear yard as the Zoning Ordinance defines it (Sec. 7.900; ARS 9-461.18(B)(6) caps ADU side and rear setbacks at 5 ft). An attached ADU keeps the main house's district rear setback. A detached ADU must also sit at least 10 ft from the main house and from any other ADU on the lot. | FY2026/27 schedule (Res. 13661, from July 1, 2026): pre-application $131, ADU staff-approval review $131, permit $237 base plus $0.94/sq ft livable and $0.54/sq ft covered, plan review $0.54 and $0.34/sq ft, CO $195, GIS $379: about $1,800 for 500 sq ft, $2,550 for 1,000 sq ft. | $160,000-$320,000 | $1,650-$2,250/mo | 6/10 |
| Surprise | The lesser of 75% of the gross floor area of the existing house or 1,000 sq ft (§106-11.3.A.2); gross floor area means interior habitable area (§106-11.2, adopting A.R.S. §9-461.18). The unit also counts toward the lot-coverage cap that applies to the house (§106-11.4.A.4): 45% on R-1 lots of 8,000-11,999 sq ft, 40% at 12,000-17,999 sq ft, 30% at 18,000-43,559 sq ft, 25% in RR and on R-1 lots of 1 acre or more (Tables 106-2b, 106-2c); no cap is listed for R-1 lots under 8,000 sq ft | No less than 5 ft from the property line (§106-11.4.A.3.a) — the ceiling state law allows (A.R.S. §9-461.18(B)(6)), against 15-30 ft for the house itself in R-1 (Table 106-2c). The unit must also sit at least 5 ft from any other structure (§106-10.3.A) and outside any existing or planned public utility easement unless every easement holder and affected utility consents in writing (§106-11.4.B) | Valuation-based (Res. 2026-16, eff. May 19, 2026): $100 + $6 per $1,000 of valuation, plan review at 65% of that, plus a 0.5%-of-valuation processing fee — about $1,700 for a 600 sq ft casita and $2,800 for 1,000 sq ft at ICC valuation; confirm the valuation basis with the city | $150,000-$280,000 | $1,400-$1,900/mo | 7/10 |
| Tempe | Lots under 1 acre: 75% of the main house's gross floor area or 1,000 sq ft, whichever is less. Lots of 1 acre (43,560 sq ft) or more: 75% or 2,000 sq ft, whichever is less. Gross floor area is interior habitable area, excluding garages, carports and exterior storage (ZDC 3-402; ADU Development Guide Step 2). District lot coverage still applies, e.g. 45% in R1-6. | 5 ft minimum in all districts unless the district or overlay allows less (ZDC 3-402; ARS 9-461.18(B)(6)). Where the lot backs onto a dedicated public alley the rear setback is measured from the midpoint of the alley (city ADU page). | Building permit fee is valuation-based per City Code Fee Schedule Table 1-A, plus a plan review fee of 65% of the permit fee (Community Development Service Fees sheet); the Residential Rebate Program refunds 100% of both after final inspection. | $150,000-$280,000 | $1,400-$1,750/mo | 8/10 |
| Tucson | 75% of the gross floor area of the principal dwelling, not to exceed 1,000 sq ft of gross floor area; a casita may always be up to 650 sq ft regardless of the size of the main house (UDC 6.6.3.B.5). Gross floor area means interior habitable area (A.R.S. 9-461.18(I)(2)). Lot coverage in R-1, R-2 and R-3 is capped at 70% for single-family use (Table 6.3-2.A), and ADUs are exempt from the zone's maximum residential density (6.6.3.B.1) | 5 ft minimum from the rear property line (UDC 6.6.3.B.6), the ceiling allowed by A.R.S. 9-461.18(B)(6). Chimneys, roof overhangs and bay windows may project 2 ft into the yard as long as 3 ft remains (6.4.5.D.1). A casita cannot be built over a public utility easement without the utility's written consent (A.R.S. 9-461.18(E)) | City fees are valuation-based (FY2027 Planning and Permitting Fee Schedule, effective July 1, 2026). Building permit for new construction: $1,038.05 plus $9.64 per $1,000 over $50,000, or $1,520.05 plus $8.25 per $1,000 over $100,000 (Section 4-02.4); building staff review (plan check) for residential is 50% of the permit fee (4-02.2.1); digital filing fee 1% (minimum $18.54). Worked example: a $120,000 valuation gives a $1,685.05 permit + $842.53 plan review + about $25 filing = roughly $2,550; at $200,000 it is about $3,550. Using an approved model plan waives the construction-document review and substitutes a $176.55 site-plan review (4-02.3.3), so the same $120,000 casita pays about $1,880. Valuation follows the ICC Building Valuation Data table; ask PDSD (pdsdinquiries@tucsonaz.gov) for the current per-square-foot figure. Setback relief via the Design Development Option costs $278.07 plus public-notice fees | $150,000-$250,000 | $950-$1,300/mo | 7/10 |
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