Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Gilbert ADU cost →Building an ADU in Gilbert costs between $130,000-$260,000 for new construction, with per-square-foot costs averaging $150-$280. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $60,000-$140,000, while prefab/modular ADUs fall in between at $90,000-$210,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | Building permit and plan review fees based on valuation — Confirm with Gilbert Development Services |
| Impact Fees | System development fees apply to new dwelling units — Confirm with Gilbert Development Services |
| 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. Get up to 3 free quotes from ADU builders serving Gilbert — no obligation.
Get Gilbert builder quotes →Permit fees in Gilbert are Building permit and plan review fees based on valuation — Confirm with Gilbert Development Services. The review timeline is Confirm with Gilbert Development Services (480-503-6700), with plan check: Full construction plan review required — Confirm with Gilbert Development Services. Impact fees are System development fees apply to new dwelling units — Confirm with Gilbert Development Services. Pre-approved plans: No pre-approved plan library — Confirm with Gilbert Development Services.
| 1-Bedroom Rent | $1,500-$1,750/month |
| 2-Bedroom Rent | $1,850-$2,300/month |
| Annual Rental Income (est.) | $19,500/year |
| Payback Period (est.) | 10.0 years |
| Short-Term Rental | Arizona law allows STRs with registration; ADU-specific STR conditions — Confirm with Gilbert Development Services |
| Overall ROI Estimate | 6-9% annual return |
A typical ADU in Gilbert generates approximately $19,500 per year in rental income based on average 1-bedroom rents. At an average construction cost of $195,000, the estimated payback period is 10.0 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Gilbert 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 Gilbert: $60,000-$140,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $90,000-$210,000.
3. Pre-approved plans — Gilbert does not offer a pre-approved/standard ADU plan program yet, so budget for custom architectural plans (typically $3,000-$15,000).
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.
Compare prices from local ADU contractors in your area. Free, no-obligation estimates.
Find ADU Contractors →