Gilbert (a town of ~270,000) is covered by Arizona HB 2720, which preempted its older casita rules that required a use permit on lots of 6,000+ sq ft. Homeowners may now build one attached and one detached ADU by right in all single-family zoning districts, with a third detached affordable unit allowed on lots over one acre. The town cannot require extra parking, design matching, or owner occupancy for long-term rentals.
Zoning & Size Requirements [1][2][3]
Yes — Gilbert allows ADUs. A detached ADU can typically be up to 1,000 sq ft under current Arizona and Gilbert zoning rules.
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| Allowed Zones | All single-family zoning districts (Gilbert Development Services ADU guidance; ARS 9-461.18) |
| Max Size (Detached) | 75% of the primary residence's gross square footage (state law guarantees at least the lesser of 1,000 sq ft or 75%) |
| Max Size (Attached) | 75% of the primary residence's gross square footage (state law guarantees at least the lesser of 1,000 sq ft or 75%) |
| Max Size (JADU) | Not a category in Arizona (no JADU designation) |
| Max Height | Same as the underlying zoning district standard for single-family homes — Confirm with Gilbert Development Services |
| Max Units | 2 per lot (1 attached + 1 detached); a 3rd detached ADU allowed on parcels over 1 acre if it is a restricted-affordable unit |
Setback Requirements [1][2][3]
Gilbert requires a rear setback of about 5 ft for a detached ADU, and no additional parking is required. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 5 feet maximum required (ARS 9-461.18 caps rear setbacks at 5 ft) |
| Side Setback | 5 feet maximum required (ARS 9-461.18 caps side setbacks at 5 ft) |
| Front Setback | Per underlying zoning district — Confirm with Gilbert Development Services |
| Parking Required | No additional parking may be required (ARS 9-461.18) |
| Owner Occupancy | Not required for long-term rentals; no familial or pre-existing-relationship test allowed |
| Min Lot Size | No ADU-specific minimum (the old 6,000 sq ft use-permit threshold was preempted); ADU must be built after the primary residence |
Permit Process & Fees [4][5]
An ADU permit in Gilbert typically costs Building permit and plan review fees based on valuation — Confirm with Gilbert Development Services and takes Confirm with Gilbert Development Services (480-503-6700), through a ministerial, by-right review.
| Approval Process | By-right building permit with construction plan review through Gilbert's One Stop Shop (no use permit or hearing) |
| Review Timeline | Confirm with Gilbert Development Services (480-503-6700) |
| Permit 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 |
| Plan Check | Full construction plan review required — Confirm with Gilbert Development Services |
| Pre-Approved Plans | No pre-approved plan library — Confirm with Gilbert Development Services |
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Construction Costs [6]
Building an ADU in Gilbert typically costs $130,000-$260,000 ($150-$280 per sq ft); a garage conversion runs $60,000-$140,000.
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| Average Build Cost | $130,000-$260,000 |
| Cost per Sq Ft | $150-$280 |
| Garage Conversion | $60,000-$140,000 |
| Prefab ADU (Installed) | $90,000-$210,000 |
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
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Rental Income Potential [7][8]
A 2-bedroom ADU in Gilbert rents for around $1,850-$2,300/mo, an estimated 6-9% annual return.
| Avg Rent (1 Bedroom) | $1,500-$1,750/mo |
| Avg Rent (2 Bedroom) | $1,850-$2,300/mo |
| Short-Term Rental | Arizona law allows STRs with registration; ADU-specific STR conditions — Confirm with Gilbert Development Services |
| Est. Annual ROI | 6-9% annual return |
Explore Prefab ADU Options
Prefab ADUs can save 20-40% vs. traditional construction and cut build time in half.
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Recent Law Changes
What's Changed Recently
- Arizona HB 2720 (ARS 9-461.18, effective Jan 1, 2025) preempted Gilbert's prior casita rules, which had required a use permit and a 6,000 sq ft minimum lot
- Gilbert scrapped its draft ADU standards revision in 2024 and adopted HB 2720-compliant regulations: one attached + one detached ADU by right on single-family lots
- Design-matching requirements (materials, colors, architecture) were eliminated by state law; ADUs no longer need to match the main dwelling
- Arizona HB 2928 (signed May 2025) extended similar ADU requirements to county land
Tips for Building an ADU in Gilbert
- Gilbert requires the ADU to be built after, and stay subordinate to, the primary residence — sequence matters on new-build lots
- The 75% gross-square-footage cap means larger homes can support larger casitas; measure your primary dwelling's GSF before designing
- Ask the One Stop Shop (onestopshop@gilbertaz.gov) about second electric meters — Gilbert publishes an ADU FAQ covering utility questions
- Long-term rentals (90+ days or month-to-month) of your casita cannot be prohibited by the town
ADU Builders in Gilbert
Looking for an ADU builder in Gilbert? ADU projects need a contractor experienced with local zoning, the permit process, and utility connections — not every general contractor has built one. We match Gilbert homeowners with experienced local ADU contractors who provide free, no-obligation quotes. Getting at least three bids typically saves 20-40% on the same scope.
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- ARS 9-461.18 — Accessory dwelling units; regulation; applicability; definitions state_statute — Accessed 2026-07-10
- Permits, Applications & Checklists (ADU Guide) — Town of Gilbert government — Accessed 2026-07-10
- New casita law preempts Gilbert's regulations — Gilbert Sun News News Source — Accessed 2026-07-10
- Permits, Applications & Checklists — Town of Gilbert Development Services government — Accessed 2026-07-10
- ADU Commonly Asked Questions — Town of Gilbert government — Accessed 2026-07-10
- ADUs in Arizona: Rules, Costs, What to Know (2026) industry — Accessed 2026-07-10
- Average Rent in Gilbert, AZ — RentCafe Market Data — Accessed 2026-07-10
- Average Rent in Gilbert, AZ — Zumper Market Data — Accessed 2026-07-10
Frequently Asked Questions
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