ADU rules in Garden Grove

Detached ADUs are allowed on any lot zoned for single-family or multifamily residential use that has a proposed or existing legally developed single-family or multifamily dwelling (9.54.020.A), which takes in the R-1, R-2 and R-3 zones and the mixed-use zones that allow housing. On a single-family lot the chapter allows one ADU and one JADU 'except as otherwise provided in Government Code Section 66323' (9.54.030.A), so a detached new-construction unit of up to 800 sq ft with 4-foot side and rear setbacks can also be added beside a conversion ADU and a JADU under Gov. Code 66323(a)(1) and (a)(2). On a lot with an existing multifamily building up to eight detached ADUs are allowed, never more than the number of existing units, and two on a lot with a proposed multifamily building (9.54.030.B, mirroring 66323(a)(4)). A detached ADU must stand 6 feet from the home and from other unattached structures (9.54.040.D), a rule HCD's March 30, 2026 findings say cannot be applied to state-exempt 66323 units. Ord. No. 2966 (adopted August 12, 2025) is the current text; the City's pending Amendment No. A-047-2026(B) leaves these location and count rules unchanged.

Attached ADUs (physically attached to the home, or to an accessory structure attached to it) and converted ADUs built within existing permitted space of a house, attached garage or accessory structure are allowed on the same residential lots (9.54.010.C.3 and C.5, 9.54.020.A), and a JADU of up to 500 sq ft may be created within the walls of a proposed or existing single-family dwelling, including an existing attached garage (9.54.050.A). An attached or converted ADU needs its own exterior entrance separate from the main home (9.54.040.H), converted ADUs need no setbacks beyond what fire and building codes require (9.54.040.C.3), and an attached ADU may be up to 25 feet or the home's height limit, whichever is lower, and no more than two stories (9.54.040.E.2). In existing multifamily buildings, converted ADUs may go in non-livable space such as storage rooms or garages: at least one, and up to 25 percent of the existing units (9.54.030.B.3). HCD's March 30, 2026 findings note that the converted-ADU definition omits conversions within a proposed single-family home, which Gov. Code 66314(d)(3) and 66323(a)(1) require; state law fills that gap until the pending amendment is adopted.

A new detached ADU may have up to 850 sq ft with a studio or one bedroom and 1,200 sq ft with two or more bedrooms; an attached ADU has the same caps or 50 percent of the primary dwelling's floor area if that is less, except that it may reach 800 sq ft when the home is under 1,600 sq ft (9.54.040.B.2). Converted ADUs that add no floor area are uncapped, a conversion of an accessory structure may add up to 150 sq ft for ingress and egress, and minimum sizes run from 150 sq ft (efficiency unit) to 700 sq ft (two or more bedrooms) (9.54.040.B.1). An ADU may add an attached porch or patio of up to 80 sq ft and an attached one-car garage of up to 250 sq ft, but the ADU plus those features may not exceed 1,530 sq ft (9.54.040.B.3); lot coverage, floor area ratio, front setback, building separation, open space and minimum lot size standards are waived only as far as needed for an 800 sq ft unit (9.54.040.A), so above 800 sq ft the zone limits can bind on small lots (in R-1, 50 percent footprint coverage counting the home, accessory structures, driveways and uncovered parking, 9.08.040.030.A.3), while the Gov. Code 66323(a)(2) state-exempt detached unit of up to 800 sq ft is subject to none of them. Heights: 16 feet for a detached ADU, 18 feet within one-half mile walking distance of a major transit stop or high-quality transit corridor (plus 2 feet to match the home's roof pitch) or on a lot with a multistory multifamily building, and 25 feet or the home's limit, whichever is lower, for an attached ADU, two stories maximum (9.54.040.E); a JADU is capped at 500 sq ft (9.54.050.B). Two state-law tensions remain open: since SB 543 (effective January 1, 2026) the Gov. Code 66321(b) size floors are measured in interior livable space while 9.54.040.B caps 'total floor area' and 9.04.060 measures gross floor area to the exterior faces of walls, and HCD's March 2026 Handbook reads a percentage cap as unable to hold an attached ADU below 850 sq ft of interior livable space (1,000 sq ft with more than one bedroom), a floor the city's rule does not guarantee for homes under 1,700 sq ft (studio or one bedroom) or 2,000 sq ft (two or more bedrooms). HCD's March 30, 2026 findings did not challenge the caps themselves, and the pending Amendment No. A-047-2026(B) keeps the same numbers while restating them as interior livable space.

No owner-occupancy requirement applies to ADUs: 9.54.060.C.1 states that owner occupancy of the primary dwelling or the ADU is not required, consistent with Gov. Code 66315, which bars an owner-occupant requirement for ADUs. JADUs differ: the city's text still requires the owner of record to live in the JADU or the rest of the home in every case (9.54.050.I.3 deed restriction and 9.54.060.C.2), but Gov. Code 66333(b), as amended by AB 1154 effective January 1, 2026, allows owner occupancy to be required only when the JADU shares sanitation facilities with the main home, and 66339.5 makes the state JADU article supersede a conflicting local ordinance. So a JADU with its own bathroom carries no owner-occupancy condition under current law, while one that shares a bathroom still does (with the usual exception for a government agency, land trust or housing organization owner). Amendment No. A-047-2026(B), recommended by the Planning Commission on August 20, 2026 but not yet before the City Council, would add the separate-sanitation exception to the deed-restriction clause. The recorded JADU deed restriction also bars separate sale, mortgage or transfer and fixes the unit's size and attributes (9.54.050.I).

Chapter 9.54 requires one off-street space for a new attached or detached ADU, in addition to the home's own parking, and allows it in setback areas or as tandem parking on a driveway unless the Director makes specific site or fire-safety findings (9.54.040.G.1-G.2). No space is required when the ADU is within one-half mile walking distance of public transit (a bus stop counts under the Gov. Code 66313(m) definition the chapter adopts), in an architecturally and historically significant historic district, for a converted ADU, where on-street permits are required but not offered to the occupant, or within one block of a car-share vehicle (9.54.040.G.3); Gov. Code 66322(a)(6) adds an ADU applied for together with a new home that meets one of those tests, and the city's submittal checklist asks for a map showing the walking distance to the nearest bus stop. Garages, carports and uncovered spaces demolished or converted for an ADU need not be replaced (9.54.040.G.2; Gov. Code 66314(d)(11)). JADUs need no additional parking: HCD's March 30, 2026 findings called the code's qualifier 'beyond that required at the time the existing primary dwelling was constructed' (9.54.050.F) noncompliant with Gov. Code 66334(a), which bars any added parking for a JADU, and the same letter found 9.54.040.G out of step with 66322(a) and 66314(d)(10). State law caps ADU parking at one space per unit or per bedroom, whichever is less (66314(d)(10)(A)); HCD's March 2026 Handbook adds that studios and efficiency units do not increase the bedroom count and that no parking may be imposed on Gov. Code 66323 state-exempt units, so the city's flat one-space rule yields for those units. The pending Amendment No. A-047-2026(B) keeps the one-space rule, cross-referencing the 66322(a) exemptions, and removes JADU parking.

ADUs and JADUs need only a building permit: the Community Development Director must approve or disapprove a complete application ministerially, without discretionary review or a public hearing, within 60 days, or within 30 days for a detached ADU that uses a city pre-approved plan or a plan identical to one approved in the current building-code cycle, and review is limited to compliance with Chapter 9.54 (9.54.070.A-C); 9.32.030.C routes ADU approvals to that chapter rather than to the site plan and hearing process. Gov. Code 66317 adds the 15-business-day completeness determination, the deemed-approved rule after 60 days and a written appeal of an incompleteness finding or denial; the pending Amendment No. A-047-2026(B) would codify these, with appeals to the Planning Commission filed within 10 days and decided within 60 days. Applications are filed online through the GG Ready (Development Access) portal; the city's ADU Go program, launched January 1, 2025, offers four free city-owned pre-approved plans from a 447 sq ft studio to a 1,000 sq ft unit, which cannot be used on lots in the FEMA Special Flood Hazard Area (Zone A). The December 2022 submittal checklist still linked as the 'ADU Application' requires a signed agreement tolling the 60-day period while corrections are pending and says refusal means automatic denial, whereas the code tolls the clock only for an applicant-requested delay (9.54.070.C.3; Gov. Code 66317(a)(3)).

An ADU or JADU may be rented separately from the primary residence but may not be sold or conveyed separately, and the lot may not be subdivided to allow separate ownership, except as Gov. Code 66341 or other law allows (9.54.060.A); Garden Grove has not opted into the Gov. Code 66342 ADU-condominium regime (the code never mentions it). A rented ADU or JADU must be rented for 30 days or longer, and short-term rental under 30 days is prohibited (9.54.060.B); for JADUs and state-exempt 66323 units state law requires a term longer than 30 days (Gov. Code 66333(g), 66323(e)). The ban matches the city's general rule: Code Enforcement treats any residential rental for less than 30 days as an illegal hotel or motel use under the permissive zoning code (9.32.020.E.1 with the R-1 and R-2/R-3 use matrices, which list no hotel or motel use), enforceable as a misdemeanor with fines of up to $1,000 per day, and runs a short-term rental hotline; SB 9 units carry their own over-30-day rule (9.56.080). Where JADU owner occupancy still applies (shared sanitation), the deed restriction provides that if owner occupancy ends the JADU becomes unhabitable space that may not be separately rented (9.54.050.I.3).