California ADU rules · Monterey County
Can I Build an ADU in Gonzales?
Yes — you can build an ADU in Gonzales. California's statewide ADU law requires every city, including Gonzales, to approve a qualifying accessory dwelling unit by right, plus a junior ADU (JADU) on a single-family lot. What varies city to city are the local specifics below.
Can you build one?
ADUs allowed
CA state lawYes — by right
ADUs and JADUs are allowed by right in all residential and mixed-use zones; ministerial approval, no hearing.
Units on a single-family lot
Local rule1 ADU (attached or detached) + 1 JADU per lot; total dwelling units (primary + ADUs/JADUs) cannot exceed 4 on any single-family lot (including SB 9 splits)
Local cap of 4 total dwellings per single-family lot, including SB 9 splits.
Units on a multifamily lot
Local ruleUp to 25% of existing units as conversions (minimum 1); up to 2 detached ADUs on lots with proposed multifamily dwellings; up to 8 detached ADUs on lots with existing multifamily dwellings, not to exceed the number of existing units
Detached ADUs on existing multifamily lots capped at number of existing units.
Junior ADU (JADU)
CA state lawAllowed
Up to 500 sq ft, within the walls of an existing single-family home (single-family lots only).
Size & height
Max detached ADU size
CA state law1,200 sq ft
Statewide default cap for detached new-construction ADUs in the absence of a compliant local ADU ordinance. The unconditional by-right floor a city must always allow is 800 sq ft (see Guaranteed minimum size); a city with a compliant ordinance may set its own ceiling.
Max attached ADU size
Local ruleMay expand up to 150 sq ft from existing dwelling; if expanded beyond 151 sq ft, max is 50% of primary living area; must allow at least 800 sq ft (or 1,000 for 2+ bedrooms) per state floor
Local rule for attached ADUs, but state minimums still apply.
Guaranteed minimum size
CA state law800 sq ft
An 800 sq ft ADU must be allowed regardless of FAR/lot-coverage caps; a city also cannot cap an attached ADU below 850 sq ft (1,000 for 2+ bedrooms).
Max JADU size
CA state law500 sq ft
Max height
CA state law16 ft
16 ft baseline; cities must allow 18 ft within ½ mi of a major transit stop or where the primary dwelling is two-story, and 20 ft on a lot with a multistory multifamily building.
Setbacks
Side setback
CA state law4 ft
A city cannot require more than 4 ft side or rear setback; conversions of existing structures are exempt.
Rear setback
CA state law4 ft
Front setback
CA state lawNo front setback may block the mandatory 800 sq ft / 16-ft / 4-ft-setback ADU; otherwise per base zone
Separation from main house
CA state lawNone required
No statewide separation requirement between the ADU and the primary dwelling.
Parking
Parking required
Local ruleNone
No parking required for attached ADUs or JADUs; detached ADUs may require up to 1 space, but broad exemptions apply.
Transit parking exemption
CA state lawYes — no parking required near transit & for conversions
No parking may be required within ½ mi walking distance of transit, in a historic district, for an ADU within an existing structure, within one block of car-share, or in certain permit-parking areas.
Garage-conversion replacement parking
CA state lawNot required
When a garage/carport is demolished or converted to build an ADU, replacement parking cannot be required.
Approval, timeline & cost
Approval path
CA state lawMinisterial (by right)
No public hearing or discretionary design review for a qualifying ADU.
Approval timeline
CA state law60 days
The agency must act within 60 days of a complete application — and the ADU is deemed approved if it does not.
Owner-occupancy
Local ruleOnly for a JADU
Owner-occupancy required for JADUs only, not for ADUs.
Impact-fee waiver
CA state lawWaived under 750 sq ft
An ADU of 750 sq ft or less pays no impact fees (the 750 sq ft threshold itself is exempt under § 66311.5); larger ADUs pay fees proportional to the primary dwelling. JADUs (≤ 500 sq ft) are exempt.
Permits required
CA state lawBuilding permit
Only a ministerial building permit — no conditional use permit or discretionary design review for a qualifying ADU.
Gonzales limits total dwellings (primary + ADUs/JADUs) to 4 per single-family lot, including SB 9 splits. Attached ADUs may be up to 25 ft tall (max 2 stories), and no parking is required for attached ADUs or JADUs.
Frequently asked questions
Can I build an ADU in Gonzales?
Yes. California's statewide ADU law requires Gonzales to approve a qualifying accessory dwelling unit ministerial (by right), plus a junior ADU (JADU) on a single-family lot.
How big can an ADU be in Gonzales?
A detached ADU of at least 1,200 sq ft must be allowed, and an ADU of 800 sq ft can never be zoned out by floor-area or lot-coverage limits. A JADU can be up to 500 sq ft.
What are the setback requirements for an ADU in Gonzales?
Side and rear setbacks are limited to 4 ft. No front setback may block the mandatory 800 sq ft / 16-ft / 4-ft-setback ADU; otherwise per base zone.
Is parking required for an ADU in Gonzales?
None. No parking can be required within ½ mile of transit, for conversions, or for units inside the primary home. When a garage is converted, replacement parking is not required.
How long does ADU approval take in Gonzales?
A complete application must be acted on within 60 days, with ministerial (by right) — no public hearing or discretionary design review for a qualifying ADU.
Do I have to live on the property to build an ADU in Gonzales?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Gonzales Municipal Code § 12.112.020 (Ord. 2025-152, 2021-128, 2020-121, 2004-29)
- Gonzales Municipal Code § 12.112.020(I), (L)
- Gonzales Municipal Code § 12.112.020(J), (K), (L)
- Gonzales Municipal Code § 12.112.020(K)(3)(b)
- Gonzales Municipal Code § 12.112.020(J)(6), (K)(6), (L)(4)
- Gonzales Municipal Code § 12.112.020(L)(8)
- Cal. Gov. Code §§ 66310–66342 (ADU Law)
- HCD 2025 Accessory Dwelling Unit Handbook
- Cal. Gov. Code § 66317 (ministerial approval, 60-day deadline)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
- Cal. Gov. Code § 66314 (local ordinance standards)
- Cal. Gov. Code § 66311.5 (impact fees: none for an ADU ≤ 750 sq ft or JADU ≤ 500 sq ft)
Last updated 2026-06-25. This is an AI-assisted summary of Gonzales's ADU rules, drawn from its published ordinance and California ADU law — general information, not legal advice, and it may be incomplete or out of date. Verify the controlling rule for your specific parcel with Gonzales Planning before relying on it.
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