Can I build a casita in Gilbert? ADU rules by district
Updated October 12, 2026
Short answer: yes. On most single-family lots in Gilbert you can build one attached and one detached casita, each up to 75% of your home's interior habitable area or 1,000 sq ft (whichever is smaller). Two things are different from Mesa and Tempe: the side and rear setback grows with the casita's height, and many Gilbert neighborhoods have their own PAD standards. Lot coverage, usually 45%, is often what decides the final size.
Gilbert's ADU rules (Land Development Code 5.2.3)
- Size: up to 75% of the main home's interior habitable area or 1,000 sq ft, whichever is less. Garages and storage don't count as habitable area.
- Setbacks that grow with height: 5 ft from the side and rear lines for an ADU up to 10 ft tall, and 1 ft more for every foot above that. Gilbert measures height to the roof surface of a flat roof, or to the midpoint of a sloped roof. A 13 ft casita needs 8 ft.
- Front setback: the same as the house in your zoning district.
- Lot coverage and height: can't exceed your zoning district's limits.
- Over 1,000 sq ft: needs an Administrative Use Permit and has to sit inside the building envelope.
- Renting: renting the ADU separately is allowed. No extra parking is required.
- Utility easements: no ADU over a public utility easement without the utility's written consent.
- Design: the ADU doesn't have to match the house, but Gilbert has exterior design standards (for example, roof-mounted mechanical equipment isn't allowed).
Lot coverage by Gilbert zoning district
Gilbert counts every structure with a roof or covering: the house, garage, covered patios, carports, sheds and even shade sails. One-story and two-story homes have different limits.
| District | One-story | Two-story | Front setback |
|---|---|---|---|
| SF-43 | 30% | 30% | 40 ft |
| SF-35 | 30% | 30% | 40 ft |
| SF-15 | 35% | 35% | 30 ft |
| SF-10 | 45% | 40% | 25 ft |
| SF-8 | 45% | 40% | 20 ft |
| SF-7 | 45% | 40% | 20 ft |
| SF-6 | 45% | 40% | 20 ft |
| SF-D | 60% | 50% | 10 ft |
| SF-A | 65% | 55% | 10 ft |
Two extras the code allows in SF-43 through SF-6: 5% more coverage for open-air patios, porches and accessory structures, and 10% more for homes that have been built and lived in for more than 20 years.
Planned Area Developments (PADs)
Many Gilbert subdivisions were approved as a Planned Area Development, with their own setbacks and coverage. Where a PAD sets a standard, it replaces the one in the table above; where it's silent, the standard code applies. If your lot or house doesn't match the standard numbers, ask the Town of Gilbert for your PAD's standards before you design.
A quick example
An SF-7 lot of 7,000 sq ft with a one-story house allows 3,150 sq ft of coverage (45%). If the house, garage and covered patio cover 2,500 sq ft, there's 650 sq ft left, so the largest new detached ADU is 650 sq ft, even if the home is big enough for 1,000. Keep it at 10 ft tall or under and it can sit 5 ft from the side and rear lines.
Before you build
- Check your HOA's CC&Rs. Many Gilbert homes are in an HOA, and state law limits the Town, not your HOA. See Can my HOA stop a casita?
- Find your PAD standards if your neighborhood has one.
- Look for easements along the rear lot line. See How to find easements on your lot.
- Talk to Gilbert's One Stop Shop about permits.
Type your Mesa, Tempe or Gilbert address. CasitaFlow pulls your parcel and zoning and shows the largest casita allowed, the setbacks, and a drawing of where it fits. Free, no account needed.
Common questions
Can I build a casita in Gilbert?
Yes, on most single-family lots. Gilbert's code allows one attached and one detached ADU where a single-family home is allowed, with no use permit for ADUs up to 1,000 sq ft. Your HOA can still have its own rules.
How big can a casita be in Gilbert?
Up to 75% of your home's interior habitable area or 1,000 sq ft, whichever is smaller, as long as the lot stays under its coverage limit. Larger ADUs need an Administrative Use Permit and have to sit inside the building envelope.
How close to the property line can a casita be in Gilbert?
5 ft from the side and rear lines for an ADU up to 10 ft tall, plus 1 ft for every foot taller. A 13 ft casita needs 8 ft. It also has to meet your district's front setback.
Do patio covers count toward lot coverage in Gilbert?
Yes. Any structure with a roof or covering counts, including covered patios, carports and shade sails. Gilbert allows 5% extra coverage for open-air patios, porches and accessory structures.
What is a PAD and does it affect my casita?
A Planned Area Development is a set of custom standards approved for a subdivision. Many Gilbert neighborhoods have one, and its setbacks and coverage replace the standard ones where they differ. Ask the Town for yours.
Sources: Town of Gilbert Land Development Code (codified, revised June 10, 2026), Section 5.2.3, Tables 3.2.4.A.1 to 3.2.4.I.1 and Section 3.2.5.F; A.R.S. § 9-461.18.