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ADU Rules in Gilbert, Arizona

Complete guide to building an Accessory Dwelling Unit in Gilbert — zoning, setbacks, permits, costs, and more.

Max Size: 75% of the primary home's gross floor area (interior habitable area), measured by LDC Section 2 'Gross Floor Area'. Up to 1,000 sq ft is by right; from 1,001 sq ft up to the 75% cap the unit needs a $1,000 Administrative Use Permit and must be inside the building envelope (LDC 5.2.3.4.c, 5.2.3.A-B). State floor: the lesser of 75% or 1,000 sq ft must be permitted (ARS 9-461.18.A.3). Setbacks: 5 ft minimum for an ADU up to 10 ft tall; add 1 ft for every foot of height over 10 ft (a 13-ft unit needs 8 ft). Units of 1,000 sq ft or less may sit inside the rear setback area; units over 1,000 sq ft must stay within the building envelope, i.e. the district rear setback of 20-40 ft (LDC 5.2.3.A.1-2, 5.2.3.B.2). State cap: 5 ft (ARS 9-461.18.B.6). No Parking Required Verified: 2026-09-20

Researched by ADU Zoning Hub · verified 2026-09-20 against Gilbert planning code and Arizona ADU law · methodology · 18 sources cited ↓

ADU Score: 6/10
Moderately friendly · how we score

Are ADUs allowed in Gilbert, AZ? [1][2][3][4]

Yes. Gilbert allows ADUs on most residential lots. A detached unit can be up to 1,000 sq ft, set 5 ft back from the rear line. No extra parking is required. Owner-occupancy is not required, so the unit can be rented out. A building permit is required and applications are reviewed administratively, without a public hearing.

Maximum size75% of the primary home's gross floor area (interior habitable area), measured by LDC Section 2 'Gross Floor Area'. Up to 1,000 sq ft is by right; from 1,001 sq ft up to the 75% cap the unit needs a $1,000 Administrative Use Permit and must be inside the building envelope (LDC 5.2.3.4.c, 5.2.3.A-B). State floor: the lesser of 75% or 1,000 sq ft must be permitted (ARS 9-461.18.A.3).
SetbacksRear 5 ft minimum for an ADU up to 10 ft tall; add 1 ft for every foot of height over 10 ft (a 13-ft unit needs 8 ft). Units of 1,000 sq ft or less may sit inside the rear setback area; units over 1,000 sq ft must stay within the building envelope, i.e. the district rear setback of 20-40 ft (LDC 5.2.3.A.1-2, 5.2.3.B.2). State cap: 5 ft (ARS 9-461.18.B.6). · Side 5 ft minimum for an ADU up to 10 ft tall; add 1 ft for every foot of height over 10 ft. Units of 1,000 sq ft or less may sit inside the side setback area; larger units must be within the building envelope (district side setback 5-30 ft) (LDC 5.2.3.A.1-2, 5.2.3.B.2). No ADU may be built over a public utility easement without the utility's written consent (LDC 5.2.3.4.d).
ParkingNone required for an ADU. Gilbert's LDC 5.2.3 sets no ADU parking standard and the town may not require added parking or in-lieu fees (ARS 9-461.18.B.3).
Owner-occupancyNot required. LDC 5.2.3.4.f allows the ADU to be rented separately from the house, and ARS 9-461.18.B.1-2 bars any owner-residency or family-relationship test for long-term rentals (90 days or longer, or month to month). Short-term rentals need a Town STR licence (see rental).

Do I need a permit to build an ADU in Gilbert? [5][6][7][8][9][10]

Yes. Every ADU in Gilbert needs a building permit. Applications are handled administratively — no public hearing.

Permit feesValuation-based: a $150,000 valuation is $1,145 permit plus $744.25 plan review (65% of the permit fee), about $1,890; add a $1,000 Administrative Use Permit if over 1,000 sq ft (Development Services Fee Schedule, Res. 4563 eff. July 1, 2025, revised Sept 15, 2026).
Typical timelinePublished review goals: 12 working days for the first review of a single-family plan set and 8 for the second (room additions 8/4); Express Permitting reviews eligible detached residential structures in 1-3 working days for the plan-review fee plus 60% (Project Review Time Frames, Mar 2026).
Official Gilbert links:

Three things to know before you build in Gilbert

  • Size to 1,000 sq ft or less if you want a straight building permit: LDC Table 3.1.2 makes a larger ADU (up to 75% of the house's gross floor area) an Administrative Use Permit ($1,000) and pushes it inside the building envelope.
  • Height drives setbacks: a 10-ft-tall casita can sit 5 ft off the rear and side lines, a 13-ft one needs 8 ft and a 16-ft one 11 ft (LDC 5.2.3.A.2.c); keep the roof low on a tight lot.
  • Utilities must come off the house's service; you may request a second electric meter or a separate address, but neither is required (ADU Guide). Avoiding a new water meter avoids the $18,000-plus water and wastewater connection fee.

Last verified 2026-09-20 against Gilbert planning code. How we verify

Yes: Gilbert allows one attached and one detached ADU (casita) by right on any lot where a single-family home is allowed, under Land Development Code Section 5.2.3, added by Ordinance 2931 (effective December 18, 2024) to comply with Arizona's casita law, ARS 9-461.18. A unit may be up to 75% of the main house's gross floor area; up to 1,000 sq ft it needs only a building permit, above that it also needs a $1,000 Administrative Use Permit and must sit inside the building envelope. Rear and side setbacks are 5 ft for a unit up to 10 ft tall plus 1 ft for every foot of height over 10 ft; height and lot coverage follow the base district (30 ft, 2 stories and 45% in most SF districts). The town cannot require extra parking, owner occupancy or design matching, and long-term rental of either unit is protected by state law. Budget about $1,900 in permit and plan-review fees on a $150,000 valuation plus $4,176.75 in system development fees; HOA CC&Rs still apply.

In Gilbert you will also hear an ADU called a casita — Arizona's ADU statute (A.R.S. §9-461.18) and most local codes use it. The rules on this page apply either way.

Outside city limits? If your property is in unincorporated Maricopa County (not within Gilbert's boundaries), different rules apply — see our Maricopa County (unincorporated) ADU rules.

Zoning & Size Requirements [1][2][3][4]

Yes — Gilbert allows ADUs. A detached ADU can typically be up to 1,000 sq ft under current Arizona and Gilbert zoning rules.

See what this means for your lot — ask Gilbert ADU builders for a quote →

Allowed ZonesAll single-family zoning districts (SF-43, SF-35, SF-15, SF-10, SF-8, SF-7, SF-6, SF-D, SF-A): an ADU under 1,000 sq ft is a permitted (P) use and one over 1,000 sq ft needs an Administrative Use Permit (A) (LDC Table 3.1.2 and Section 5.2.3, Ord. 2931 eff. Dec 18, 2024). In commercial, office and employment districts an ADU is allowed only as a facility-manager unit (note L34). Tribal land and high-noise airport areas are outside the state mandate (ARS 9-461.18.G).
Max Size (Detached)75% of the primary home's gross floor area (interior habitable area), measured by LDC Section 2 'Gross Floor Area'. Up to 1,000 sq ft is by right; from 1,001 sq ft up to the 75% cap the unit needs a $1,000 Administrative Use Permit and must be inside the building envelope (LDC 5.2.3.4.c, 5.2.3.A-B). State floor: the lesser of 75% or 1,000 sq ft must be permitted (ARS 9-461.18.A.3).
Max Size (Attached)Same as detached: 75% of the primary home's gross floor area, by right up to 1,000 sq ft, Administrative Use Permit above that (LDC 5.2.3.4.c, Table 3.1.2). The ADU must be subordinate to the house and built after it (LDC 5.2.3.2-4).
Max Size (JADU)Not a category in Gilbert or in Arizona law. A unit converted inside the house counts as the one attached ADU allowed per lot and follows the same 75% cap (LDC 5.2.3.3).
Max HeightSame as the base zoning district (LDC 5.2.3.4.b): 30 ft / 2 stories in SF-10, SF-8, SF-7 and SF-6; 35 ft / 2 stories in SF-43 and SF-35; 36 ft / 3 stories in SF-D and SF-A (Tables 3.2.4.A-I.1). Height is measured from finished floor or grade, whichever is lower, to a flat roof or the midpoint of a sloped roof (ADU Guide). Every foot over 10 ft adds 1 ft to the rear and side setback.
Max UnitsOne detached and one attached ADU per lot; a second detached ADU on parcels of one acre or more if at least one ADU is a restricted-affordable unit (rented to households at or below 80% of area median income under a deed restriction or development agreement) (LDC 5.2.3.3; ARS 9-461.18.A.1-2, I.6).

Setback Requirements [1][2][3][4]

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 Setback5 ft minimum for an ADU up to 10 ft tall; add 1 ft for every foot of height over 10 ft (a 13-ft unit needs 8 ft). Units of 1,000 sq ft or less may sit inside the rear setback area; units over 1,000 sq ft must stay within the building envelope, i.e. the district rear setback of 20-40 ft (LDC 5.2.3.A.1-2, 5.2.3.B.2). State cap: 5 ft (ARS 9-461.18.B.6).
Side Setback5 ft minimum for an ADU up to 10 ft tall; add 1 ft for every foot of height over 10 ft. Units of 1,000 sq ft or less may sit inside the side setback area; larger units must be within the building envelope (district side setback 5-30 ft) (LDC 5.2.3.A.1-2, 5.2.3.B.2). No ADU may be built over a public utility easement without the utility's written consent (LDC 5.2.3.4.d).
Front SetbackSame front setback as the primary house in its district (LDC 5.2.3.A.2.a): 20 ft in SF-8, SF-7 and SF-6; 25 ft in SF-10; 40 ft in SF-43 and SF-35 (Tables 3.2.4.A-G.1). Planned Area Development overlays may modify these.
Parking RequiredNone required for an ADU. Gilbert's LDC 5.2.3 sets no ADU parking standard and the town may not require added parking or in-lieu fees (ARS 9-461.18.B.3).
Owner OccupancyNot required. LDC 5.2.3.4.f allows the ADU to be rented separately from the house, and ARS 9-461.18.B.1-2 bars any owner-residency or family-relationship test for long-term rentals (90 days or longer, or month to month). Short-term rentals need a Town STR licence (see rental).
Min Lot SizeNo ADU-specific minimum lot size: any lot where a single-family home is allowed qualifies (ARS 9-461.18.A; the old 6,000 sq ft use-permit threshold is gone). Combined building footprints must stay within the district lot-coverage cap: 45% one-story / 40% two-story in SF-10 through SF-6, 30% in SF-43 and SF-35 (LDC 5.2.3.4.a, Tables 3.2.4). The ADU must be built after the primary home (LDC 5.2.3.2).

Permit Process & Fees [5][6][7][8][9][10]

An ADU permit in Gilbert goes through a ministerial, by-right review. Typical timeline: Published review goals: 12 working days for the first review of a single-family plan set and 8 for the second (room additions 8/4); Express Permitting reviews eligible detached residential structures in 1-3 working days for the plan-review fee plus 60% (Project Review Time Frames, Mar 2026). Permit fees: Valuation-based: a $150,000 valuation is $1,145 permit plus $744.25 plan review (65% of the permit fee), about $1,890; add a $1,000 Administrative Use Permit if over 1,000 sq ft (Development Services Fee Schedule, Res. 4563 eff. July 1, 2025, revised Sept 15, 2026).

Approval ProcessBy-right building permit through the Development Services One Stop Shop (electronic plan review) for an ADU up to 1,000 sq ft; over 1,000 sq ft, obtain a $1,000 Administrative Use Permit from Planning first. Plans must show front-elevation articulation (all sides on two-story units), ground-mounted screened mechanical equipment and utilities fed from the house's service (LDC 5.2.3.5; Town ADU Guide).
Review TimelinePublished review goals: 12 working days for the first review of a single-family plan set and 8 for the second (room additions 8/4); Express Permitting reviews eligible detached residential structures in 1-3 working days for the plan-review fee plus 60% (Project Review Time Frames, Mar 2026).
Permit FeesValuation-based: a $150,000 valuation is $1,145 permit plus $744.25 plan review (65% of the permit fee), about $1,890; add a $1,000 Administrative Use Permit if over 1,000 sq ft (Development Services Fee Schedule, Res. 4563 eff. July 1, 2025, revised Sept 15, 2026).
Impact FeesSystem Development Fees for an ADU: $2,339.50 parks and recreation + $438.50 traffic signals + $752.50 roads + $284.50 police + $361.75 fire = $4,176.75, one quarter of the single-unit rate (adopted April 16, 2024, effective July 1, 2024). Water and wastewater connection fees ($18,396-$18,603 for a 3/4-inch meter) apply only if a new or larger meter is needed; ADU utilities normally come off the house, so confirm with the One Stop Shop (480-503-6728).
Plan CheckFull construction plan review through the One Stop Shop; a soils report is required unless the subdivision has one on file or you sign the Town's soils waiver; a third or later review may be billed at $150 per hour; expedited review costs twice the plan-review fee (Fee Schedule pp. 8-9; ADU Guide).
Pre-Approved PlansNone published on gilbertaz.gov as of Sept 20, 2026. ARS 9-461.20 (SB 1529, Laws 2025 ch. 259) requires every Arizona municipality to offer at least three pre-approved ADU design plans from July 1, 2026; ask the One Stop Shop whether Gilbert's are available.

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Construction Costs [11][12][13]

Building an ADU in Gilbert typically costs $150,000-$280,000 ($175-$350 per sq ft); a garage conversion runs $80,000-$150,000.

See what this means for your lot — ask Gilbert ADU builders for a quote →

Average Build Cost$150,000-$280,000
Cost per Sq Ft$175-$350
Garage Conversion$80,000-$150,000
Prefab ADU (Installed)$150,000-$300,000

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Rental Income Potential [14][15][16][17][18]

A 2-bedroom ADU in Gilbert rents for around $1,850-$2,300/mo, an estimated 6-11% gross rental yield.

Avg Rent (1 Bedroom)$1,500-$1,800/mo
Avg Rent (2 Bedroom)$1,850-$2,300/mo
Short-Term RentalYes, with a Town of Gilbert Short-Term Rental licence (registration through Neumo/GovOS; licence and renewal fee $250 from Oct 1, 2026), an ADOR TPT licence and written notice to adjacent neighbors (STR ordinance adopted.
Est. Annual ROI6-11% gross rental yield

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Recent Law Changes

What's Changed Recently

  • Ordinance 2931 (effective December 18, 2024) added LDC Section 5.2.3 and the ADU rows of Table 3.1.2 to comply with ARS 9-461.18 (HB 2720, Laws 2024 ch. 196): one attached plus one detached ADU by right, 75% gross-floor-area cap with 1,000 sq ft by right, 5-ft rear and side setbacks with a 1-ft-per-foot stepback above 10 ft, no parking, owner-occupancy or design-matching requirement; it replaced the prior use-permit casita rules.
  • Arizona HB 2928 (Laws 2025 ch. 217, signed May 2025) restructured ARS 9-461.18 without changing the mandate, extended ADU rules to county land (ARS 11-810.01) and let cities require short-term-rental owner residency on lots whose ADU was finaled on or after Sept 14, 2024 (ARS 9-500.39(B)(9)); Gilbert has not adopted that option.
  • ARS 9-461.20 (SB 1529, Laws 2025 ch. 259) requires Gilbert to offer at least three pre-approved ADU design plans from July 1, 2026; none were posted on gilbertaz.gov as of Sept 20, 2026.
  • Development Services Fee Schedule revised Sept 15, 2026 (permit and plan-review tables per Resolution 4563, effective July 1, 2025); the ADU system development fee has been $4,176.75 since July 1, 2024. The short-term rental licence fee rises to $250 on Oct 1, 2026.
  • Re-verified Sept 20, 2026 against the codified LDC (revision of June 10, 2026, which lists no ADU amendment after Ord. 2931), the Town's ADU Guide, the fee schedule, the March 2026 review-timeframe sheet and ARS 9-461.18, 9-461.20 and 9-500.39.

Tips for Building an ADU in Gilbert

  • Size to 1,000 sq ft or less if you want a straight building permit: LDC Table 3.1.2 makes a larger ADU (up to 75% of the house's gross floor area) an Administrative Use Permit ($1,000) and pushes it inside the building envelope.
  • Height drives setbacks: a 10-ft-tall casita can sit 5 ft off the rear and side lines, a 13-ft one needs 8 ft and a 16-ft one 11 ft (LDC 5.2.3.A.2.c); keep the roof low on a tight lot.
  • Utilities must come off the house's service; you may request a second electric meter or a separate address, but neither is required (ADU Guide). Avoiding a new water meter avoids the $18,000-plus water and wastewater connection fee.
  • Ask for Express Permitting: residential detached structures and garage conversions can be reviewed in 1-3 working days for the plan-review fee plus 60% (Plan Review Programs, rev. 11/2024). Projects in the floodplain or on lots needing on-lot retention are not eligible.
  • HOA CC&Rs still apply: ARS 9-461.18(C) leaves private covenants intact, and the Town's ADU Guide tells you to check with your HOA before designing.
  • Gilbert enforces the 2018 I-Codes and 2017 NEC with local amendments (adopted Jan 1, 2020, Ord. 2739); the Residential Addition, Alteration & Accessory checklist lists the sheets a casita permit needs.
  • Cost basis: Phoenix-metro builder guides dated May 2026 ($150,000-$250,000 for a 500-800 sq ft detached casita, $250,000-$400,000-plus custom, $80,000-$150,000 garage conversion, $150-$400 per sq ft; prefab $200,000-$400,000 installed); rents from HUD FY2027 Small Area FMRs for Gilbert ZIPs (1BR $1,750-$2,240 gross, 2BR $2,030-$2,600), RentCafe Aug 31, 2026 (1BR $1,553, 2BR $1,854) and Zumper Sept 19, 2026 (1BR $1,489, 2BR $1,937).
  • Cost basis (2026-09-20 re-verification): short term allowed: Yes, with a Town of Gilbert Short-Term Rental licence (registration through Neumo/GovOS; licence and renewal fee $250 from Oct 1, 2026), an ADOR TPT licence and written notice to adjacent neighbors (STR ordinance adopted June 2023). Gilbert has not adopted the ARS 9-500.39(B)(9) option to require owner residency where the ADU was finaled on or after Sept 14, 2024; check the STR page before listing.

ADU Builders in Gilbert

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Sources & References

All data on this page is sourced from official government records and verified market data. View our full methodology.

  1. Town of Gilbert Land Development Code (codified PDF, revision of June 10, 2026): Section 5.2.3 Accessory Dwelling Unit, Table 3.1.2 Use Regulations, Tables 3.2.4 Single Family districts, amendment table (Ord. 2931 eff. 12-18-24) government — Accessed 2026-09-20
  2. Land Development Code page (Ord. 2809 adopted Sept 21, 2021; latest revision June 10, 2026) - Town of Gilbert Planning government — Accessed 2026-09-20
  3. A Guide to Accessory Structures and Accessory Dwelling Units (ADU Guide, Feb 2025) - Town of Gilbert Development Services government — Accessed 2026-09-20
  4. ARS 9-461.18 - Accessory dwelling units; regulation; applicability; definitions state_statute — Accessed 2026-09-20
  5. Permits, Applications & Checklists - Town of Gilbert Development Services (One Stop Shop) government — Accessed 2026-09-20
  6. Development Services Fee Schedules (revised Sept 15, 2026): Planning fees p.2-4, connection fees p.5, System Development Fees p.6, Building Permit and Plan Review table p.8, misc. fees p.9 government — Accessed 2026-09-20
  7. Project Review Time Frames - Plan Review & Inspection Division (Mar 2026) government — Accessed 2026-09-20
  8. Plan Review Programs (Express Permitting, Expedited, PBA; rev. 11/2024) - Town of Gilbert government — Accessed 2026-09-20
  9. Building Code Adoption Dates - Town of Gilbert government — Accessed 2026-09-20
  10. ARS 9-461.20 - Municipal housing; standard preapproved housing design plans state_statute — Accessed 2026-09-20
  11. ADUs in Arizona: Rules, Costs, What to Know (2026) - Fenn Rogers Custom Homes, Mesa (updated May 12, 2026) industry — Accessed 2026-09-20
  12. How Much Does It Cost to Build a Casita in Arizona? (2026 Guide) - Rise Above Remodeling, Phoenix industry — Accessed 2026-09-20
  13. Prefab Modular ADU: 2026 Costs, Code Paths & Lot Fit - Dwelling Index (updated May 27, 2026) industry — Accessed 2026-09-20
  14. HUD FY2027 Small Area Fair Market Rent Schedule - Phoenix-Mesa-Chandler MSA ZIP table (Gilbert ZIPs 85233-85298) government — Accessed 2026-09-20
  15. Average Rent in Gilbert, AZ - RentCafe (updated Aug 31, 2026) Market Data — Accessed 2026-09-20
  16. Gilbert, AZ Rent Research - Zumper (updated Sept 19, 2026) Market Data — Accessed 2026-09-20
  17. Short-Term Rentals - Town of Gilbert Business Registration and Licensing government — Accessed 2026-09-20
  18. ARS 9-500.39 - Vacation rentals; short-term rentals; regulation (B.9 ADU owner-residency option) state_statute — Accessed 2026-09-20

Frequently Asked Questions

Can I build an ADU in Gilbert?

Yes. ADUs are allowed in All single-family zoning districts (SF-43, SF-35, SF-15, SF-10, SF-8, SF-7, SF-6, SF-D, SF-A): an ADU under 1,000 sq ft is a permitted (P) use and one over 1,000 sq ft needs an Administrative Use Permit (A) (LDC Table 3.1.2 and Section 5.2.3, Ord. 2931 eff. Dec 18, 2024). In commercial, office and employment districts an ADU is allowed only as a facility-manager unit (note L34). Tribal land and high-noise airport areas are outside the state mandate (ARS 9-461.18.G). in Gilbert. The maximum size for a detached ADU is 75% of the primary home's gross floor area (interior habitable area), measured by LDC Section 2 'Gross Floor Area'. Up to 1,000 sq ft is by right; from 1,001 sq ft up to the 75% cap the unit needs a $1,000 Administrative Use Permit and must be inside the building envelope (LDC 5.2.3.4.c, 5.2.3.A-B). State floor: the lesser of 75% or 1,000 sq ft must be permitted (ARS 9-461.18.A.3).. Owner-occupancy is not required, so you can rent out the ADU.

How much does an ADU cost in Gilbert?

ADU construction in Gilbert typically costs $150,000-$280,000. Garage conversions run $80,000-$150,000, and prefab ADUs cost $150,000-$300,000.

How much can I rent an ADU for in Gilbert?

Average ADU rents in Gilbert are $1,500-$1,800/mo for a 1-bedroom and $1,850-$2,300/mo for a 2-bedroom unit.

Do I need parking for an ADU in Gilbert?

None required for an ADU. Gilbert's LDC 5.2.3 sets no ADU parking standard and the town may not require added parking or in-lieu fees (ARS 9-461.18.B.3).. Check with Gilbert planning department for the latest Arizona ADU parking rules, as many states have relaxed requirements in recent years.

How long does it take to get an ADU permit in Gilbert?

The permit review timeline in Gilbert is Published review goals: 12 working days for the first review of a single-family plan set and 8 for the second (room additions 8/4); Express Permitting reviews eligible detached residential structures in 1-3 working days for the plan-review fee plus 60% (Project Review Time Frames, Mar 2026).. Permit fees: Valuation-based: a $150,000 valuation is $1,145 permit plus $744.25 plan review (65% of the permit fee), about $1,890; add a $1,000 Administrative Use Permit if over 1,000 sq ft (Development Services Fee Schedule, Res. 4563 eff. July 1, 2025, revised Sept 15, 2026).

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Gilbert ADU FAQ

Answers to every common question about building an ADU in Gilbert — costs, rules, permits, rental income.

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Gilbert ADU Costs

Detailed cost breakdown: construction $150,000-$280,000, garage conversion $80,000-$150,000, plus ROI analysis.

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Garage Conversion ADU Guide

Complete guide to costs ($80K-$180K), impact fee savings, and permits for garage-to-ADU conversions.

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ADU vs Mother-in-Law Suite

Legal differences that affect what you can build, how you can use it, and rental rights.

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About this information: This page is an informational summary of publicly available regulations - it is not legal, financial, or professional advice, and it is not a substitute for confirming requirements with your local planning department. Rules change frequently; always verify current requirements before designing, budgeting, or building. Last verified: 2026-09-20. Contractors we introduce are independent businesses - verify license and insurance directly before hiring. Spotted an error? Tell us - we verify against primary sources and correct quickly.

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