California ADU rules · Los Angeles County
Can I Build an ADU in Whittier?
Yes — you can build an ADU in Whittier. California's statewide ADU law requires every city, including Whittier, 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 detached ADU + 1 attached ADU + 1 JADU
Allows both 1 detached and 1 attached ADU per single-family lot, in addition to 1 JADU.
Units on a multifamily lot
Local ruleup to 25% of existing units as conversion ADUs (minimum 1), plus up to 8 detached ADUs (not to exceed number of existing units); up to 2 detached ADUs on lots with proposed multifamily dwellings
Detached ADUs on multifamily lots capped at number of existing units; up to 2 detached ADUs on lots with proposed multifamily dwellings.
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
Detached ADUs: 1,200 sq ft max for new construction; up to 1,500 sq ft on lots ≥20,000 sq ft.
Max attached ADU size
Local rulegreater of 850 sq ft (0–1 bedroom) or 1,000 sq ft (2+ bedrooms), or 50% of primary dwelling
Attached ADU size is the greater of the state minimums or 50% of the primary dwelling.
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
25 ft max for both attached and detached ADUs; attached ADUs also limited to height of primary dwelling if lower.
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 rule5 ft
5 ft minimum separation between detached ADU and primary dwelling, unless it would preclude an 800 sq ft ADU.
Parking
Parking required
Local ruleUp to 1 space
1 space per ADU unless exempt; exemptions include proximity to transit, historic districts, and other state-standard 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
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
CA state lawOnly for a JADU
No owner-occupancy requirement for ADUs (the prior sunset was removed). A JADU may require owner-occupancy, principally where it shares sanitation with the main house.
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.
Whittier-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Insufficient water/sewer
ADUs not allowed in areas with insufficient water/sewer as determined by the director.
Historic Districts
No parking required for ADUs in historic districts.
Whittier allows both 1 detached and 1 attached ADU plus 1 JADU per single-family lot, and permits detached ADUs up to 1,500 sq ft on large lots. A 5 ft separation is required between detached ADUs and the primary dwelling unless it would preclude an 800 sq ft ADU.
Frequently asked questions
Can I build an ADU in Whittier?
Yes. California's statewide ADU law requires Whittier 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 Whittier?
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 Whittier?
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 Whittier?
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 Whittier?
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 Whittier?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- WMC §18.10.030(I)
- WMC §18.10.030(I)(c)(i)
- WMC §18.10.030(I)(c)(ii)-(iii)
- WMC §18.10.030(I)(d)(ii)
- WMC §18.10.030(I)(d)(i)
- WMC §18.10.030(I)(H), (I)(14)(ii)(c)
- WMC §18.10.030(I)(b)(ii)
- WMC §18.10.030(I)(f)
- WMC §18.10.030(I)(e)
- 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 § 66315 (owner-occupancy)
- 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 Whittier'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 Whittier Planning before relying on it.
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