California ADU rules · Los Angeles County
Can I Build an ADU in Rolling Hills?
Yes — you can build an ADU in Rolling Hills. California's statewide ADU law requires every city, including Rolling Hills, 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 (up to 800 sq ft), 1 JADU (within existing/proposed SFR, max 500 sq ft), 1 conversion ADU; all three may be allowed if site conditions permit
Allows up to 3 units (1 detached, 1 JADU, 1 conversion) if feasible; more permissive than state baseline.
Units on a multifamily lot
Local ruleConversions: at least 1, up to 25% of units from non-livable space; Detached: up to 2 on proposed multifamily, up to 8 on existing multifamily (not to exceed number of existing units)
Detached ADUs on 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
Local rule1,000 sq ft
Detached ADU max: 850 sq ft (studio/1-bed), 1,000 sq ft (2+ beds); cannot be reduced below 800 sq ft.
Max attached ADU size
Local rule850 (studio/1-bed), 1,000 (2+ beds), AND no more than 50% of primary dwelling; never less than 800 sq ft
Both numeric and percent-based cap, but 800 sq ft always 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
Local rule30 ft minimum
Local front setback is 30 ft, more restrictive than state default.
Separation from main house
CA state lawNone required
No statewide separation requirement between the ADU and the primary dwelling.
Parking
Parking required
Local ruleUp to 1 space
1 off-street space per ADU or per bedroom, whichever is less; state 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 for garage/carport conversions.
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
No owner-occupancy for ADUs; JADUs may require deed restriction.
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 ruleADU permit, Building permit
Both ADU and building permits required.
Rolling Hills-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Historic district
ADU parking requirement is waived if property is in a historic district.
Rolling Hills allows up to three ADU/JADU units on a single-family lot if site conditions permit, and sets a local maximum size of 1,000 sq ft for detached/attached ADUs with a 30 ft front setback. Parking is required unless state exemptions apply, and no replacement parking is needed for garage conversions.
Frequently asked questions
Can I build an ADU in Rolling Hills?
Yes. California's statewide ADU law requires Rolling Hills 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 Rolling Hills?
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 Rolling Hills?
Side and rear setbacks are limited to 4 ft. 30 ft minimum.
Is parking required for an ADU in Rolling Hills?
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 Rolling Hills?
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 Rolling Hills?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Rolling Hills Municipal Code Chapter 17.28 (Ord. No. 388, § 4(Exh. A), 12-9-2025)
- §17.28.040(B)(1)(a)-(b)
- §17.28.040(B)(1)(c)-(d)
- §17.28.060(A)(1)-(3)
- §17.28.060(A)(2)-(3)
- §17.28.060(C)(3)
- §17.28.060(G)(1)-(2)
- §17.28.060(G)(3)
- §17.28.110(H)
- §17.28.120(A)(1)
- §17.28.060(G)(2)(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 § 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 § 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 Rolling Hills'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 Rolling Hills Planning before relying on it.
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