Everything homeowners ask about building an ADU in Buckeye — answered with 2026 data.
Yes, ADUs are allowed in Permitted (P) as an accessory use in every district where a single-family detached dwelling is allowed: AG, R1-43, R1-18, R1-10, R1-6, R1-3, R1-1, MF-1 and DR (Downtown Residential) in Table 3.1-1, keyed to §3.3.4.A, plus the obsolete districts that allow single-family dwellings (Appendix C, note 1). Not listed in MF-2, MH, the NMU/CMU/RMU/IMU/DC mixed-use districts or any commercial or industrial district. Airport-vicinity and tribal land are outside the state mandate (A.R.S. §9-461.18(G)) in Buckeye, AZ. The maximum size for a detached ADU is 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). Attached ADUs can be up to Same rule — 75% of the house's gross floor area, no flat ceiling. Buckeye has an ADU-friendliness score of 7/10. Check our full Buckeye ADU rules page for complete zoning details.
ADU construction in Buckeye typically costs $150,000-$280,000. The cost per square foot averages $175-$350. Garage conversions are more affordable at $80,000-$150,000, while prefab ADUs cost $150,000-$300,000. Permit fees add $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) to your budget. See our detailed Buckeye ADU cost guide.
Detached ADUs in Buckeye can be up to 75% of the gross floor area of the single-family dwelling on the same lot. Attached ADUs are limited to Same rule — 75% of the house's gross floor area, no flat ceiling. Junior ADUs (JADUs) have a cap of Not a category in Arizona — Buckeye's Development Code has no junior ADU designation; a converted room or garage is simply an attached ADU under §3.3.4.A. Maximum height is The principal-dwelling height of the district, because an ADU follows the site and building standards for principal dwellings (§3.3.4.A.2) rather than the 24-foot cap on ordinary accessory structures (§3.3.3.C.2, which excepts ADUs): 35 feet in AG, R1-43, R1-18, R1-10 and R1-6; 45 feet in R1-3 and R1-1; 40 feet in MF-1 (Table 4.1-1); DR follows §5.13.4.H. You are allowed up to 2 per single-family lot — one attached plus one detached ADU on a qualifying lot.
Rear setback: 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)). Side setback: 5 feet from the property line (§3.3.4.A.2) — the state-law ceiling; corner lots next to an arterial right-of-way add 5 feet on that side (Table 4.1-1, note 3). Front setback: The district's front setback for a principal dwelling (§3.3.4.A.2; Table 4.1-1): 40 ft in AG and R1-43, 25 ft in R1-18, 20 ft in R1-10, 12 ft in R1-6 and R1-3, 0 ft in R1-1, 15 ft in MF-1; a front-loaded garage sits 40 ft back in AG and R1-43, 25 ft in R1-18 and 20 ft in the other districts. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
None — 'Parking for vehicles is not required for an ADU' (§3.3.4.A.7; A.R.S. §9-461.18(B)(3)), and the city may not charge an in-lieu fee. 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 — §3.3.4.A is silent on occupancy and rental terms, and state law bars Buckeye from prohibiting separate long-term leasing of the house or the ADU or requiring any family or other relationship between occupants (A.R.S. §9-461.18(B)(1)-(2)). A rented ADU is residential rental property that must be registered with the Maricopa County Assessor (City Code Article 8-10). 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 Buckeye is typically about 10 business days for the first plan review of a residential accessory structure, then 5 business days for each later review (Plan Review Timeframes Guideline, effective Sept 28, 2023, average per review); total time depends on resubmittals. Plan check: Full plan review under Buckeye's building and fire codes (Chapter 15). No separate utility service unless the public utility determines a separate meter is required for safety (§3.3.4.A.5). State law bars a commercial building code or a fire-sprinkler requirement for an ADU (A.R.S. §9-461.18(D)). Third and later reviews cost $130 per hour, re-inspections $106, expedited review doubles the fee, and a permit expires after 180 days without an inspection (fee schedule §0 and §4). Pre-approved plans availability: Yes — three pre-approved ADU plans, Buckeye Casita 200, Saguaro Casita 600 and Sonoran Casita 1000 (square feet — the three sizes A.R.S. §9-461.20(A)(4) requires from July 1, 2026), each with three elevations and a floor plan, under the Pre-Approved Housing and ADU Design Plan Program; three house plans at 1,200, 1,600 and 2,000 sq ft sit alongside them. Any deviation (wall changes, slab to wood floor, structural or truss changes) voids the pre-approval.
Average ADU rental income in Buckeye: 1-bedroom units rent for $1,350-$1,750/month, 2-bedroom units for $1,700-$2,150/month. Short-term rentals: No local short-term rental licence or ordinance was found in the Buckeye City Code (Chapters 7, 8 and 10, codified through May 5, 2026) or on the city website, so state law governs: Arizona bars cities from prohibiting v. Expected ROI: 6-11% gross rental yield.
The minimum lot size for an ADU in Buckeye is No ADU-specific minimum lot size, and ADUs are exempt from the district's maximum residential density (§3.3.4.A.6). Lot coverage applies only where Table 4.1-1 sets a maximum (25% in AG, 30% in R1-43; the R1-18 through MF-1 cells carry none). A lot of 1 acre or more can add a third unit (see units). 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 Buckeye, 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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