Gilbert casitas: what the rules allow and what it costs

Gilbert casita rules

Gilbert updated its land development code in December 2024 to follow the state ADU law (Council packet, Z24-05).

• Arizona's 2024 casita law (HB 2720, ARS 9-461.18) requires cities with more than 75,000 people to allow one attached and one detached accessory dwelling unit (ADU) on single-family lots without a public hearing.
• Under these laws, cities and counties cannot require more than a 5-foot side or rear setback for an ADU, cannot require extra parking for it, and cannot require it to match your home's design.
• Cities and counties must allow an ADU of at least 75% of the home's interior living area or 1,000 square feet, whichever is less. Some allow larger ADUs with extra conditions.
• You can rent an ADU long-term (90 days or more, or month to month). The city cannot require the tenant to be a relative or employee.

Gilbert's own ADU section adds details on height and placement, so ask the town about your lot before you design.

The HOA question comes first in Gilbert

Many Gilbert neighborhoods have an HOA. The state ADU laws do not override HOA rules. If your HOA's CC&Rs limit casitas or tall detached buildings, those rules still apply.

Before you pay for plans, read your CC&Rs and ask the architectural committee three things:

• Are casitas allowed?
• How tall can a detached building be?
• What finish must it match?

Shops and RV garages in Gilbert

We have not confirmed Gilbert's current height and setback numbers for detached shops and RV garages, so ask the town before you design, especially with a 14 ft door.

A 14-foot RV door usually means 16 to 18 foot walls and an 18 to 22 foot roof peak. That is taller than the reduced-setback height limit in Queen Creek, Chandler and Mesa. The 5-foot ADU setback applies to the living unit, not to a shop or RV bay. See shops and RV garages.

More on costs: RV garage cost by size and RV garage with a casita.

Gilbert cost notes

Gilbert's own permit data shows big backyard buildings are on the rise (Town of Gilbert permit data):

• New residential accessory structure permits valued at $50,000 or more: 20 a year in 2023 and 2024, 53 in 2025, and 60 in 2026 through Sept. 24.
• The average valuation of those 2026 permits was $168,423. They include casitas, garages and shops together.

One Gilbert casita builder publishes 250 sq ft at $99,000 ($396 per sq ft) and 1,000 sq ft at $220,000 ($220 per sq ft). That spread is why our table charges more per foot under 500 sq ft. See the 2026 table.

How to choose a casita builder in Gilbert

We do not rank or recommend builders. Use this checklist with any contractor you talk to.

1. Check the ROC license. Search the contractor on the Arizona Registrar of Contractors site. Make sure the license is active and covers residential work, and that the name matches the bid.
2. Ask for proof of insurance. Get a certificate for liability insurance, and for workers' comp if they have employees.
3. Get a written bid. It should list plans, permits, site work, utility runs, the slab, AC and finishes, plus any allowances. Compare it line by line with our line items.
4. The contractor should pull the permits. Ask who pulls them. If you are asked to pull them yourself, ask why.
5. Tie payments to finished work. Avoid paying most of the price up front.
6. Ask for local projects. Ask how they handle HOA approval, since many Gilbert lots have an HOA.

Areas we cover in Gilbert

Southeast Gilbert ZIPs 85296, 85297 and 85298. Some addresses with a Gilbert mailing address are in unincorporated county islands, which follow Maricopa County rules. See county island casitas.

Where to start

1. Make sure your lot is inside town limits and find your zoning.
2. Get HOA approval in writing.
3. Ask the town's planning staff about ADU height and placement for your lot.
4. Get a licensed builder's quote and site plan.