California ADU rules · San Bernardino County
Can I Build an ADU in Chino Hills?
Yes — you can build an ADU in Chino Hills. California's statewide ADU law requires every city, including Chino 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 ADU (detached or attached) + 1 JADU; if detached ADU, limited to 800 sq ft and 18 ft height
Detached ADU + JADU combo only if detached ADU is max 800 sq ft/18 ft.
Units on a multifamily lot
Local ruleConversions (>=1 or 25% of units) + up to 8 detached (not to exceed number of existing units)
Detached ADUs capped at 8 or number of existing units, whichever is less.
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: 800 sq ft if combined with JADU; otherwise 850 (1-bed) or 1,000 (2+ bed).
Max attached ADU size
Local rule850 (1-bed) or 1,000 (2+ bed), but cannot exceed 50% of primary if over 800 sq ft
State floor of 800 sq ft applies regardless of percentage.
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 rule18 ft
Detached ADU max 18 ft; attached ADU may match primary or up to 25 ft.
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 ruleSame as required for the primary dwelling
No special ADU front setback; must match primary dwelling.
Separation from main house
Local ruleNone required
No fixed minimum; must comply with building/fire code separation.
Parking
Parking required
Local ruleUp to 1 space
1 space per ADU unless exempted.
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 required for ADU; required for JADU garage conversion.
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 JADU, not for ADU.
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
Additional requirements if on septic (percolation test).
Chino Hills-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Fire Hazard Overlay District (VHFHSZ)
ADUs must comply with Fire Hazard Overlay standards if in mapped area.
ADU Ineligibility District (e.g., Carbon Canyon)
Some areas are ineligible for ADUs except under specific criteria.
Septic System Areas
Additional percolation test required for ADUs on septic.
Chino Hills limits detached ADUs to 800 sq ft/18 ft if combined with a JADU, and otherwise caps detached ADUs at 1,000 sq ft. Some areas, such as Carbon Canyon, are ineligible for ADUs except under special criteria.
Frequently asked questions
Can I build an ADU in Chino Hills?
Yes. California's statewide ADU law requires Chino 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 Chino 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 Chino Hills?
Side and rear setbacks are limited to 4 ft. Same as required for the primary dwelling.
Is parking required for an ADU in Chino 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 Chino 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 Chino Hills?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Chino Hills Municipal Code § 16.10.140 (Ord. No. 417, § 5(Exh. A), 2-11-2025)
- Chino Hills Municipal Code § 16.10.140(H)
- Chino Hills Municipal Code § 16.10.140(J)
- Chino Hills Municipal Code § 16.10.140(M)
- Chino Hills Municipal Code § 16.10.140(K)
- Chino Hills Municipal Code § 16.10.140(E)
- Chino Hills Municipal Code § 16.10.140(P)
- Chino Hills Municipal Code § 16.10.140(P)(3)
- Chino Hills Municipal Code § 16.10.140(C)
- Chino Hills Municipal Code § 16.10.140(W)
- Chino Hills Municipal Code § 16.10.140(F)-(G)
- 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 Chino 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 Chino Hills Planning before relying on it.
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