Riverside County

Norco ADU rules

Research summary of what we found for City of Norco in Riverside County. Not a determination for a specific lot.

Last checked November 3, 2026.

City or county ADU page

Norco Planning department. No ADU-specific page was found.

How big can an ADU be in Norco?

Maximum size
An attached or detached ADU may be up to 850 sq ft with one bedroom or less, or 1,000 sq ft with two or more bedrooms. When there is an existing home, an attached ADU is also limited to 50% of the home's living space, if that is smaller. Patios and covered porches of a detached ADU are limited to 50 sq ft each. Size, percentage, lot coverage, open space (including animal-keeping areas) and front setback limits are waived when they would block an ADU of at least 800 sq ft with 4 ft side and rear setbacks.
Source: Norco Municipal Code § 18.30.46 Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360), § 18.30.46(E)(1), (E)(19)(a), accessed 2026-11-02.

ADU setbacks in Norco

Setbacks and location
New ADUs need 4 ft side and rear setbacks; conversions of existing living area or accessory structures, and rebuilds in the same place and size, need none. An ADU must be 10 ft from all other buildings on the lot, may not be in the front yard setback area, and a detached ADU may not sit between the front property line and the back of the main home (conversions excepted). These limits cannot be applied to an ADU that meets Gov. Code § 66323(a) where they conflict with it, and front setback limits are waived when they would block an 800 sq ft ADU. A wall or fence is needed where an ADU is closer than 5 ft to a side or rear line.
Source: Norco Municipal Code § 18.30.46 Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360), § 18.30.46(E)(2), (E)(9), (E)(11), (E)(19), accessed 2026-11-02.

What we found for Norco

What we have for this place. Where a local figure is stricter than the California state baseline, both are shown.

Local ADU rules
Norco's ADU rules are in Municipal Code Section 18.30.46, last amended by Ordinance No. 1138 (February 4, 2026). ADUs and JADUs need only a building permit and are reviewed ministerially, without a hearing. The City says within 15 business days whether an application is complete and acts on it within 60 days of a complete application when the lot already has a home.
Source: Norco Municipal Code § 18.30.46 Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360), § 18.30.46(D)(1)-(5) (Ord. 1138, 2/4/2026), accessed 2026-11-02.

How many ADUs per lot
On a single-family lot: one ADU and one JADU, plus a second ADU that meets Gov. Code § 66323(a)(1) or (a)(2), but no more than one attached ADU (which includes one inside an existing accessory structure) and one detached ADU. On a lot with existing multifamily homes: ADUs in non-livable space (at least one, up to 25% of existing units) plus up to eight detached ADUs, not more than the number of existing units. On a lot with proposed multifamily homes: up to two detached ADUs.
Source: Norco Municipal Code § 18.30.46 Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360), § 18.30.46(B)(1)(a), (E)(5), accessed 2026-11-02.

Height
A detached ADU may be 16 ft, measured from the finished floor to the tallest roof peak. It may be 18 ft within a half mile walk of a major transit stop or high-quality transit corridor (up to 20 ft to match the main home's roof pitch), or on a lot with a multistory multifamily building. An ADU attached to the main home may be 25 ft or the home's height limit, whichever is lower. No ADU may be more than two stories.
Source: Norco Municipal Code § 18.30.46 Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360), § 18.30.46(E)(13), accessed 2026-11-02.

Parking
One space per ADU, 9 ft by 20 ft, which need not be covered and may be tandem in the main home's driveway. No space is needed within a half mile walk of public transit, in a historic district, for an ADU inside the home or an accessory structure, where on-street permits are required but not offered, within one block of a car share pick-up spot, or when the ADU is filed with a new home or multifamily building. Garage, carport or covered spaces removed for an ADU do not have to be replaced. JADUs need no added parking.
Source: Norco Municipal Code § 18.30.46 Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360), § 18.30.46(E)(8), (F)(8), accessed 2026-11-02.

Animal-keeping areas and septic systems
An ADU must keep the lot's recorded primary animal-keeping area (or the zone's animal-keeping open space) and a clear access at least 12 ft wide to it; for an ADU under Gov. Code § 66323(a), this applies only if the ADU can still fit elsewhere on the lot, and it is waived when it would block an 800 sq ft ADU. No new private septic system is allowed for an ADU; an existing septic system must be expanded unless sewer is within 200 ft. Detached ADUs need a separate water meter.
Source: Norco Municipal Code § 18.30.46 Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360), § 18.30.46(E)(15), (E)(18), (E)(19), accessed 2026-11-02.

Junior ADUs
A JADU may be up to 500 sq ft inside the walls of a proposed or existing single-family home (an attached garage counts), with an efficiency kitchen and its own entrance (plus an interior door if it shares a bathroom). The owner must live in the home or the JADU unless the JADU has its own sanitation. It may not be sold separately or rented for 30 days or less. No parking, separate utility connection or impact fee is needed.
Source: Norco Municipal Code § 18.30.46 Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360), § 18.30.46(F), accessed 2026-11-02.

Fees and sprinklers
No impact fees for an ADU up to 750 sq ft; larger ADUs pay in proportion to the main home. An ADU is not a new unit for water and sewer connection or capacity fees. Fire sprinklers are needed only if the main home needs them. ADUs may be rented for at least 30 days and may not be sold separately except as Gov. Code § 66341 allows.
Source: Norco Municipal Code § 18.30.46 Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360), § 18.30.46(C), (E)(7), (E)(15), (E)(17), accessed 2026-11-02.

City checklist and contact
The City's ADU/JADU options checklist (updated July 16, 2024) lists older figures, including a 1,200 sq ft detached ADU; the code section above is newer. For questions, contact the Norco Planning Division at (951) 270-5662.
Source: City of Norco, Accessory Dwelling (ADU)/Junior Accessory Dwelling (JADU) Options/Checklist, Checklist, last updated 07/16/2024, accessed 2026-11-02.

State housing department (HCD) review
On October 3, 2023, HCD found that Norco's ADU ordinance (No. 1093, adopted February 15, 2023) did not comply with state ADU law on separate sale, the bedroom wording of the size limit, the number of ADUs per lot, a code citation, and the JADU interior entry. The City had until November 2, 2023 to respond. It has since amended the section several times, most recently by Ordinance No. 1138 (2026). No newer HCD letter was found.
Source: HCD ordinance review letter, City of Norco, Letter of October 3, 2023, accessed 2026-11-02.

California state rules

The statewide baseline recorded from state law and the HCD ADU Handbook.

Detached size cap described in state law
1,200 sq ft. From Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Side and rear setback cap for a new ADU
4 ft. From Government Code section 66314, which describes a cap on side and rear setbacks for a new ADU.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Setback for a conversion of an existing structure
No additional setback, from Government Code section 66314 for a conversion of an existing structure.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Minimum lot size
A city may not impose a minimum lot size for an ADU, from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Minimum unit the handbook says cities must allow
At least an 800 sq ft ADU with 4 ft side and rear setbacks. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(3).
Source: HCD ADU Handbook, 66321(b)(3); handbook updated March 2026, accessed 2026-10-16.

Detached height described in the handbook
16 ft, or 18 ft or 20 ft in some cases. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(4).
Source: HCD ADU Handbook, 66321(b)(4); handbook updated March 2026, accessed 2026-10-16.

Permit decision deadline
60 days. From Government Code section 66317(a)(3): the permitting agency must decide on (approve or deny) a completed ADU application within 60 days when an existing single-family or multifamily dwelling is on the lot. Section 66317(a)(1) says the application is considered ministerially, without discretionary review or a hearing.
Source: California Government Code section 66317, 66317(a)(1), (a)(3), accessed 2026-10-17.

Owner-occupancy requirement
None. From Government Code section 66315: a local agency may not impose an owner-occupancy requirement on an ADU. It may require that the property be used for rentals of terms 30 days or longer. The HCD ADU Handbook (updated March 2026) describes the same rule.
Source: California Government Code section 66315, 66315; HCD ADU Handbook updated March 2026, accessed 2026-10-17.

Parking near public transit
No parking standards within one-half mile walking distance of public transit. From Government Code section 66322(a)(1). Section 66322(a) lists several other cases where parking standards may not be imposed.
Source: California Government Code section 66322, 66322(a), accessed 2026-10-17.

Ministerial categories
The HCD ADU Handbook (updated March 2026) states that Government Code section 66323 sets four ministerial categories. What we have does not restate those four categories.
Source: HCD ADU Handbook, 66323; handbook updated March 2026, accessed 2026-10-16.

Fire Hazard Severity Zones
If your lot is in a Fire Hazard Severity Zone, the CAL FIRE Office of the State Fire Marshal says in Information Bulletin 25-004 (issued March 3, 2025): “Fire Hazard Severity Zones (FHSZs) should not restrict the development of Accessory Dwelling Units (ADUs). However, additional building standards may be necessary, including but not limited to California Fire Code Chapter 49 and California Building Code Chapter 7A.” State ADU law does not itself bar an ADU there. A city or county may still apply its building code, including wildfire-resistant construction (Gov. Code 66314(d)(8)); require side and rear setbacks “sufficient for fire and safety” for a unit converted under 66323(a)(1); and decline parking in setbacks on specific fire and life safety findings (66314(d)(10)(B)). It may also consider public safety when it designates where ADUs may be permitted (66314(a)). Sprinklers can't be required in an ADU or JADU if the primary residence doesn't need them (66314(d)(12), 66323(d)). Some cities and counties still apply their own fire-zone limits. Where this summary has one, it is listed with the local rules. This summary does not look up your lot. Check the CAL FIRE Fire Hazard Severity Zone map viewer linked from the State Fire Marshal's Fire Hazard Severity Zones page: https://experience.arcgis.com/experience/5065c998b4b0462f9ec3c6c226c610a9
Source: CAL FIRE Office of the State Fire Marshal Information Bulletin 25-004, page 4, issued March 3, 2025; Gov. Code 66314, 66323, accessed 2026-10-20.

State baseline on the directory → · State ADU rules on the homepage →

Can I build an ADU in Norco?

State law sets a baseline for ADUs in Norco, and what we found locally is listed on this page. Whether a specific lot can add an ADU depends on zoning, utilities, and other site facts this page does not measure. Confirm with the City of Norco Planning Division, or run a free address summary.

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