California ADU rules · Los Angeles County
Can I Build an ADU in Alhambra?
Yes — you can build an ADU in Alhambra. California's statewide ADU law requires every city, including Alhambra, 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 rule2 detached ADUs per lot with a proposed multifamily dwelling, or up to 8 detached ADUs per lot with an existing multifamily dwelling (not to exceed the number of existing units); at least 1 attached ADU or up to 25% of existing units as conversions
Local cap of 2 detached ADUs for proposed multifamily, up to 8 for existing multifamily; not to exceed 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
Local rule1,200 sq ft
1,200 sq ft max for single-family lot detached ADUs; 850/1,000 sq ft for multifamily lots.
Max attached ADU size
Local rulegreater of 50% of primary dwelling, 850 sq ft (1 bedroom or less), or 1,000 sq ft (2+ bedrooms)
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
Local rule25 ft
Local cap of 25 ft and two stories for all ADUs.
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
Local rulemust comply with the front yard setback of the underlying zone
No local exception for ADUs; must meet base zone front setback.
Separation from main house
Local rule5 ft
Detached ADUs must maintain 5-foot separation from primary dwelling (eave to eave).
Parking
Parking required
Local ruleUp to 1 space
1 space per ADU; no parking required for JADUs; multiple local exemptions.
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 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
Local rule60 days
30 days if using a city preapproved plan.
Owner-occupancy
Local ruleOnly for a JADU
No owner-occupancy for ADUs; JADUs require owner-occupancy of either JADU or main dwelling.
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
Local ruleBuilding permit
No separate planning application required; other permits may apply.
Alhambra-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Fire code compliance
ADUs must comply with all applicable building, health, and fire codes; sprinklers not required unless for main dwelling.
Historic parcels
No parking required for ADUs on historic parcels.
Alhambra sets a 25-foot height cap for all ADUs and requires a 5-foot separation between detached ADUs and the primary dwelling. Multifamily lots have a local cap of 2 detached ADUs for proposed buildings and up to 8 for existing buildings, not to exceed the number of existing units.
Frequently asked questions
Can I build an ADU in Alhambra?
Yes. California's statewide ADU law requires Alhambra 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 Alhambra?
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 Alhambra?
Side and rear setbacks are limited to 4 ft. must comply with the front yard setback of the underlying zone.
Is parking required for an ADU in Alhambra?
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 Alhambra?
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 Alhambra?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Alhambra Zoning Code, ADU/JADU sections (2024 update)
- Alhambra Zoning Code § (B)(3)-(6)
- Alhambra Zoning Code § (D)(1)(a)-(b)
- Alhambra Zoning Code § (D)(1)(c)
- Alhambra Zoning Code § (F)
- Alhambra Zoning Code § (D)(2)(b), (f)
- Alhambra Zoning Code § (D)(2)(c)
- Alhambra Zoning Code § (G)(1)-(4)
- Alhambra Zoning Code § (G)(3)
- Alhambra Zoning Code § (C)(1)
- Alhambra Zoning Code § (H)
- Alhambra Zoning Code § (I)
- Alhambra Zoning Code § (G)(4)(b)
- 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 § 66333 (junior ADUs)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
- 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 Alhambra'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 Alhambra Planning before relying on it.
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