California ADU rules · Los Angeles County
Can I Build an ADU in San Gabriel?
Yes — you can build an ADU in San Gabriel. California's statewide ADU law requires every city, including San Gabriel, 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
CA state law1 ADU + 1 JADU
At least one ADU and one JADU per single-family lot (a conversion ADU may also be possible).
Units on a multifamily lot
Local ruleup to 2 detached + conversions (>=1 or 25% of units); no JADUs allowed
San Gabriel limits detached ADUs on multifamily lots to 2, and prohibits JADUs on multifamily lots.
Junior ADU (JADU)
Local ruleAllowed
JADUs allowed only on single-family lots.
Size & height
Max detached ADU size
Local rule1,000 sq ft
Detached ADUs capped at 850 sq ft (studio/1-bed) or 1,000 sq ft (2-bed); must allow at least 800 sq ft by state law.
Max attached ADU size
Local rule50% of primary dwelling or detached ADU max (850/1,000 sq ft), whichever is less; must allow at least 800 sq ft
Attached ADU max is the lesser of 50% of primary or detached ADU max; 800 sq ft minimum must be allowed.
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
Local rule6 ft
6 ft minimum separation required between ADU and any other building on the lot.
Parking
Parking required
Local ruleUp to 1 space
1 space per unit or per bedroom, whichever is less; multiple 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
Local ruleNot required
No replacement parking required when garage/carport/covered parking is converted to ADU.
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 only for JADUs.
Impact-fee waiver
Local ruleWaived under 750 sq ft
No impact fees for ADUs under 750 sq ft; proportional fees above.
Permits required
Local ruleBuilding permit, Demolition permit (for garage conversion)
Demolition permit for garage conversion issued concurrently with building permit.
San Gabriel-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Fire lane and fire flow requirements
New ADUs/JADUs require a 10-ft wide fire lane within 150 ft and minimum fire flow of 1,000 gpm, unless exempted by state law.
Historic district visibility and garage demo notice
ADUs in historic districts must not be visible from the public right-of-way; garage demolition in historic districts requires notice.
San Gabriel sets a local detached ADU cap of 850/1,000 sq ft and requires a 6 ft separation between ADUs and other buildings. Multifamily lots are limited to 2 detached ADUs and no JADUs are allowed on multifamily properties.
Frequently asked questions
Can I build an ADU in San Gabriel?
Yes. California's statewide ADU law requires San Gabriel 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 San Gabriel?
A detached ADU of at least 1,000 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 San Gabriel?
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 San Gabriel?
Up to 1 space. 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 San Gabriel?
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 San Gabriel?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- San Gabriel Municipal Code § 153.047 (2024)
- SGMC § 153.047(A), (Q), (P)
- SGMC § 153.047(P), (Q)
- SGMC § 153.047(D)
- SGMC § 153.047(E)
- SGMC § 153.047(7)(7)
- SGMC § 153.047(7)(9)
- SGMC § 153.047(M)(1)
- SGMC § 153.047(P)(7)(a)
- SGMC § 153.047(T)
- SGMC § 153.047(T), (I)
- SGMC § 153.047(L)
- SGMC § 153.047(7)(2), (I)
- 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 § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
Last updated 2026-06-25. This is an AI-assisted summary of San Gabriel'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 San Gabriel Planning before relying on it.
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