Building a casita in Gilbert, Arizona

How the state ADU law applies in Gilbert

Gilbert has a population well above 75,000, so it's covered by Arizona's new state ADU statute. That means the city is required to allow, on any single-family lot:

• At least one attached accessory dwelling unit (part of your existing home).
• At least one detached accessory dwelling unit — a true backyard casita.
• A third detached ADU on lots of one acre or more, if one unit is deed-restricted affordable.

The baseline Gilbert must follow

• Size: up to 1,000 sq ft on lots ≤ 10,000 sq ft; the lesser of 3,000 sq ft or 10% of net lot area on larger lots — and never more than 75% of the main home's gross floor area.
• Setbacks: Gilbert cannot require setbacks greater than 5 feet.
• Parking: Gilbert cannot require additional off-street parking beyond what the primary home has.
• Owner-occupancy: Gilbert cannot require you to live in the main house.
• Materials: Gilbert cannot require exterior materials that match the primary dwelling.
• Height / coverage: Gilbert cannot impose stricter height or lot-coverage limits on the ADU than on the primary home.

What the state law guarantees you in Gilbert

Gilbert exceeds the 75,000-population threshold, so Arizona's state ADU statute applies. On a single-family lot the town must allow:

• At least one attached ADU and one detached ADU per lot.
• Size up to 1,000 sq ft on lots ≤ 10,000 sq ft, or the lesser of 3,000 sq ft / 10% of net lot area on larger lots — never more than 75% of the main home.
• 5-foot maximum setbacks.
• No extra off-street parking beyond what the main home already has.
• No owner-occupancy requirement.

For a multigenerational plan — aging parents in a detached casita, or a returning adult child with some independence — that baseline is a genuinely useful floor.

What to confirm with the town

Gilbert's specific permit process, submittal checklist, plan-review timeline, impact fees, and any rental-related rules are set locally. Confirm current requirements with Gilbert's Planning Division before you design or hire a builder. Pair this with our casita cost guide, our financing options, and the HOA rules page — HOAs are especially common in Gilbert.

What still varies by city

Even though the state sets the baseline, Gilbert's specific permit process, submittal checklist, plan-review timeline, and impact fees are set locally. Building codes, mechanical requirements, and utility connection rules are also administered by Gilbert and its utility providers. Confirm the details with the Gilbert planning department before you sign anything with a builder.

HOAs still matter in Gilbert

Big chunks of Gilbert sit inside HOA-governed neighborhoods. The state ADU law does not override private HOA covenants (CC&Rs). Read yours before you start. Our HOA rules page walks through exactly what to look for.

Practical steps for Gilbert homeowners

• Pull your CC&Rs and confirm your neighborhood permits detached ADUs (or that you have no HOA).
• Call Gilbert planning and ask for their current ADU submittal checklist under the new state statute.
• Get a survey. Setbacks are 5 feet minimum — no guessing.
• Line up financing before you commission plans. See our financing guide.
• Get at least two contractor bids with itemized scope.

What a casita costs in Gilbert

Costs in Gilbert track the metro Phoenix baseline: roughly $150 to $300+ per square foot, with most detached builds landing between $150,000 and $300,000 all-in. Utility runs, site conditions, HOA design requirements, and contractor overhead drive most of the variance. Read the full Arizona casita cost guide.