Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Glendale ADU cost →Building an ADU in Glendale costs between $150,000-$280,000 for new construction, with per-square-foot costs averaging $175-$350. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $80,000-$150,000, while prefab/modular ADUs fall in between at $150,000-$300,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | $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 |
| Impact Fees | Yes, but small since Sept 8, 2025: the Development Impact Fee Schedule (updated 6/24/2026) charges an ADU, attached or detached, 25% of the single-family rate — fire $212.50, library $88.75, parks $298.50, police $175.50, streets $0 — $775.25 in total. Water and wastewater impact fees apply only if the ADU's demand forces a larger meter, and then only the difference between sizes (3/4-inch to 1-inch: $11,898 − $7,125 = $4,773). The March 2025 handout's $9,630 detached / $8,780 attached impact-fee figures predate this schedule |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. We pass your request to up to 5 local builders serving Glendale, where we have them — free, no obligation.
Get Glendale builder quotes →Permit fees in Glendale are $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. The review timeline is 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), with 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. Impact fees are Yes, but small since Sept 8, 2025: the Development Impact Fee Schedule (updated 6/24/2026) charges an ADU, attached or detached, 25% of the single-family rate — fire $212.50, library $88.75, parks $298.50, police $175.50, streets $0 — $775.25 in total. Water and wastewater impact fees apply only if the ADU's demand forces a larger meter, and then only the difference between sizes (3/4-inch to 1-inch: $11,898 − $7,125 = $4,773). The March 2025 handout's $9,630 detached / $8,780 attached impact-fee figures predate this schedule. Pre-approved plans: 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.
| 1-Bedroom Rent | $1,200-$1,750/month |
| 2-Bedroom Rent | $1,400-$2,050/month |
| Annual Rental Income (est.) | $17,700/year |
| Payback Period (est.) | 12.1 years |
| Short-Term Rental | 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. |
| Overall ROI Estimate | 5-10% gross rental yield |
A typical ADU in Glendale generates approximately $17,700 per year in rental income based on average 1-bedroom rents. At an average construction cost of $215,000, the estimated payback period is 12.1 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Glendale and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Glendale: $80,000-$150,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $150,000-$300,000.
3. Pre-approved plans — available in Glendale, which can save $3,000-$10,000 in design costs and 2-3 months in review time. See which cities offer pre-approved ADU plans.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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