Everything homeowners ask about building an ADU in Glendale — answered with 2026 data.
Yes, ADUs are allowed in any zoning district that allows a single-family dwelling, on a lot or parcel that already has one (UDC §35.3.204.A.3) — RR-45, SR-30/17/12, R1-10/8/7/6/4 and any other zone that permits a house. Not allowed on a lot with a duplex or other multifamily development, whatever the zoning (A.4), and never before the main house is built (A.5). Tribal and airport-vicinity parcels sit outside the state mandate (A.R.S. §9-461.18(G)) in Glendale, AZ. The maximum size for a detached ADU is 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. Attached ADUs can be up to Same cap — up to the house's gross floor area, never more than 1,000 sq ft. Glendale has an ADU-friendliness score of 7/10. Check our full Glendale ADU rules page for complete zoning details.
ADU construction in Glendale 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 $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 to your budget. See our detailed Glendale ADU cost guide.
Detached ADUs in Glendale can be up to the gross floor area of the existing house, but never more than 1,000 sq ft. Attached ADUs are limited to Same cap — up to the house's gross floor area, never more than 1,000 sq ft. Junior ADUs (JADUs) have a cap of Not a category in Arizona — Glendale's code has no junior ADU. A converted garage or other permitted accessory building becomes an ordinary ADU and must meet every ADU standard (UDC §35.3.204.A.18). Maximum height is The zoning district's maximum for a house (UDC §35.3.204.A.12): 30 ft and two stories in R1-10, R1-8, R1-7, R1-6 and R1-4 (Table 2.300-2) and 30 ft in RR-45 and SR-30/17/12 (Table 2.200-2). The general 16-ft cap on accessory buildings in R1/RR/SR districts (§35.3.203.C.1) is written for garages and sheds, and state law bars a stricter height for an ADU than for the house (A.R.S. §9-461.18(B)(5)) — confirm at zoning clearance if you plan two stories. You are allowed up to 2 per lot — one attached plus one detached ADU on a qualifying lot.
Rear setback: 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). Side setback: No less than 5 ft from each side property line (UDC §35.3.204.A.11.b), which is also the state-law ceiling (A.R.S. §9-461.18(B)(6)). The house itself needs 5 and 10 ft in R1-8/7/6 and 10 ft in R1-10 (Table 2.300-2); ask the planner how the 10-ft street-side minimum is applied on a corner lot. Front setback: No less than the front-yard setback of the zoning district (UDC §35.3.204.A.11.c): 15 ft to living area and 20 ft to a front-entry garage in R1-10 through R1-4 (Table 2.300-2), 25 ft in SR-17 and SR-12, 40 ft in RR-45 and SR-30 (Table 2.200-2). A detached ADU must also sit behind the nearest front plane of the house (§35.3.203.B.1). Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
None — no additional parking space or in-lieu fee may be required (UDC §35.3.204.A.20; A.R.S. §9-461.18(B)(3)). The ADU may not have its own driveway or parking area separate from the house's (A.20), and front-yard paving stays within §35.4.006 — at most 50% of the front yard on lots under 8,000 sq ft, 40% on larger lots. 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 for a long-term lease. Since Ord. O25-45 (adopted Nov 25, 2025) the rule applies only to short-term rentals: to rent either unit for under 30 days the owner (title holder or contract purchaser) must live in the house or the ADU (UDC §35.3.204.A.25). The old A.26 ban on renting an ADU separately when neither unit was owner-occupied was deleted, in line with A.R.S. §9-461.18(B)(1)-(2). Owners with an ADU certificate of occupancy on or before Sept 14, 2024 are exempt (A.26). 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 Glendale is typically about 10 working days for the zoning-clearance determination (UDC §35.6.210.B.4), then a 10-business-day target for the first building plan review of room additions and accessory buildings, 15 for custom home plans (city Plan Review Turnaround Times sheet). Plan check: Full residential plan review under the 2024 International Building, Residential and Fire Codes with city amendments, adopted Dec 9, 2025 and effective Jan 9, 2026 (UDC §35.3.204.A.22). State law bars a commercial code or a fire-sprinkler requirement for an ADU (A.R.S. §9-461.18(D)). Budget for the separate city water meter every ADU must have (A.24): a new tap to the main in the street, a right-of-way permit and a licensed contractor. Expedited review halves the target time at 300% of the plan-review fee. Pre-approved plans availability: Yes — the Glendale Permit-Ready Plan Program (live 2026, meeting A.R.S. §9-461.20) offers three free ADU plans: a 204 sq ft studio, a 512 sq ft 2-bedroom (36 ft × 16 ft) and a 994 sq ft 2-bedroom with study, each in ranch, contemporary and Spanish elevations, plus three house plans. No modifications allowed. Site plan review costs $61.44 planning + $122.88 building + $35.89 engineering with a 10-business-day target, then permit and impact fees.
Average ADU rental income in Glendale: 1-bedroom units rent for $1,200-$1,750/month, 2-bedroom units for $1,400-$2,050/month. Short-term rentals: Yes, with conditions: to rent either unit for under 30 days the owner must occupy the house or the ADU as their principal residence (UDC §35.3.204.A.25; authority A.R.S. Expected ROI: 5-10% gross rental yield.
The minimum lot size for an ADU in Glendale is No ADU-specific minimum lot size — an ADU is allowed wherever a house is (UDC §35.3.204.A.3) and does not count as a dwelling unit for density (A.1). The district's lot-coverage cap is the practical limit: 40% in R1-10/8/7/6, 45% in R1-4, 20–35% in RR-45 and the SR districts, with accessory buildings counted (§35.3.203.C.4). A lot of 1 acre or more unlocks a third unit (A.10). 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 Glendale, 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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