Everything homeowners need to know about building an accessory dwelling unit in Garden Grove - size limits, setbacks, permits, and the city's free pre-approved plan program, on top of California's statewide ADU law.
Last verified: August 2026
7/10 · ADU-friendly
1,200 sq ft*
Max ADU size
16 ft*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes Garden Grove Municipal Code Chapter 9.54 (Accessory Dwelling Units and Junior Accessory Dwelling Units) and California's statewide ADU law (Government Code Sections 66310-66342) for general reference - it is not legal advice. The state flagged several provisions of the city's current ordinance for further amendment in 2026 (see ordinance history below). Always confirm current requirements with Garden Grove Planning Services before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new construction)
850 sq ft (studio/1-bedroom) or 1,200 sq ft (2+ bedrooms)
16 ft; up to 18 ft on a multifamily lot with a multistory dwelling or within a half-mile of a major transit stop, plus up to 2 ft more for a matching roof pitch
4 ft side/rear setbacks; a 6 ft separation from the primary dwelling and other structures is required by local code
Attached (addition)
850 sq ft or 50% of the primary dwelling (studio/1-bedroom), 1,200 sq ft or 50% (2+ bedrooms), whichever is smaller; up to 800 sq ft regardless if the primary home is under 1,600 sq ft
25 ft or the primary dwelling's height limit, whichever is lower; max 2 stories
Must match the primary home's roof, wall, and window/door materials and colors, unless built from a pre-approved plan
Converted ADU (within existing structure)
No separate maximum if floor area isn't increased; up to a 150 sq ft expansion allowed for ingress/egress
Not height-limited
No setbacks required if the existing structure's setbacks are fire- and safety-adequate
Junior ADU (JADU)
500 sq ft, within existing walls
Within existing primary structure
Deed restriction required before permit issuance
Allowed zoning districts
Any lot zoned for single-family or multi-family residential use citywide, under Garden Grove Municipal Code Chapter 9.54. In no case can the combined footprint of an ADU plus an attached porch, patio, and/or one-car garage exceed 1,530 sq ft. Confirm your parcel's zoning with Garden Grove Planning Services.
Additional standards
Setbacks, parking & other rules
Setbacks
4 ft minimum from side and rear property lines for new attached and detached ADUs; front setback generally matches other structures on the lot, though a portion of an ADU may extend into the front setback if needed to reach 800 sq ft; a new ADU garage that opens to a street or alley needs a 20 ft setback
Parking
1 space required for a new attached or detached ADU, allowed in setback areas or via tandem parking; waived within a half-mile of transit, in a historic district, for converted ADUs, and a few other listed cases. No parking is required for a JADU
Units per lot
1 ADU + 1 JADU on a single-family lot. On a lot with an existing multifamily building: up to 8 detached ADUs (not exceeding the existing unit count) plus converted ADUs up to 25% of existing units. On a lot proposed for new multifamily development: up to 2 detached ADUs
Owner-occupancy
Not required for a standard ADU. JADUs require the owner to occupy either the JADU or the remaining home, backed by a recorded deed restriction, unless the owner is a public agency, land trust, or housing organization
Building code
Standard building, fire, and related code requirements apply; the city's ordinance confirms that adding an ADU does not itself trigger a fire-sprinkler retrofit requirement for the existing primary home
Rental rules
An ADU or JADU can be rented but not sold or conveyed separately from the primary home (with limited statutory exceptions). Rentals of less than 30 days are prohibited
Ordinance history
How Garden Grove's ADU rules got here
2017Statewide by-right ADU law takes effect. California Government Code Section 65852.2 begins requiring cities, including Garden Grove, to approve most ADUs ministerially; UC Berkeley's Center for Community Innovation graded the city's original ordinance a C in its 2020 statewide ADU scorecard.
2023GG Ready launches. Garden Grove rolls out its fully digital "GG Ready" permitting portal, moving plan-check submittals online.
2024Owner-occupancy ban made permanent. AB 976, effective January 1, 2024, permanently prohibits California cities from requiring owner-occupancy for standard ADUs.
2025Ordinance No. 2966 rewrites Chapter 9.54. Following a Planning Commission hearing on June 5, 2025 and a City Council public hearing on July 8, 2025 (passed 5-1), the city adopted Ordinance No. 2966 on August 12, 2025, restating Chapter 9.54 to align with recent state law, raise height limits, allow up to 8 detached ADUs on qualifying multifamily lots, and formalize the ADU Go pre-approved plan program.
2026State finds remaining compliance gaps. An HCD review letter dated March 30, 2026 found that Ordinance No. 2966 still fell short of state law in a dozen places, including its 6 ft building-separation requirement, minimum unit sizes tied to bedroom count, and a mandatory design-matching provision, and required the city to respond by April 29, 2026.
Worth knowing: Orange County as a whole saw ADU permits climb from roughly 1,367 in 2024 to about 1,916 in 2025, according to real estate data provider Cotality, a 40% jump. Garden Grove's own ADU Go program, four free city-designed plans ranging from a 447 sq ft studio to a 1,000 sq ft three-bedroom, is one of the more homeowner-friendly local programs in the county, even as the underlying ordinance continues to be refined under state review.
Permit process
How Garden Grove ADU permitting works
1
Pre-application check
Confirm your zoning and lot capacity with Garden Grove Planning Services, (714) 741-5312, before you design.
2
Choose custom plans or ADU Go
Use one of the city's four free pre-approved ADU Go plans (447 to 1,000 sq ft) to skip the architectural-compatibility review, or submit a fully custom design.
3
Prepare your submittal
You'll need a site plan, Title 24 energy compliance documents, and structural plans and calculations, even when using a pre-approved ADU Go plan.
4
Submit through GG Ready
All new applications go through the city's online GG Ready plan-check portal to the Building and Safety Division, (714) 741-5307.
5
Ministerial review
The Director must approve or disapprove a complete application within 60 days (30 days for a pre-approved or previously approved identical plan), with no discretionary hearing; an application not acted on in time is automatically approved.
6
Building permit & inspections
Pull your building permit, begin construction, and schedule the standard framing, plumbing, electrical, and final inspections.
Properties in flood zones can't use the pre-approved ADU Go plans. Fees and timelines are approximate - confirm current figures with Garden Grove Planning Services or Building and Safety.
Budgeting
What it costs to build an ADU in Garden Grove
Garage conversion
Roughly $70,000-$180,000, the least expensive path since the shell already exists
Basement conversion
Uncommon in Garden Grove's largely slab-built housing stock; where feasible, costs run comparable to or higher than a garage conversion
New detached ADU
Roughly $150,000-$340,000+ for a code-compliant, freestanding unit; using a free ADU Go pre-approved plan can reduce design costs
Permit fees
Reported at roughly $5,000-$25,000 depending on project scope; ADUs under 750 sq ft are exempt from local impact fees, and larger units are charged proportionally to the primary dwelling's square footage
ADU Go plans
Free, city-owned pre-approved architectural plans; applicants still pay standard plan-check, permit, school, and utility fees
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, finishes, and whether you use a free ADU Go plan versus a fully custom design.
Before you apply
Tips for a smooth approval
Look at ADU Go before hiring a designer. The city's four free pre-approved plans (447 to 1,000 sq ft) skip the architectural-compatibility review and can meaningfully cut your design timeline and cost.
Plan for the 6 ft separation rule as it stands today. The state flagged this requirement as potentially unlawful in a March 2026 letter, but until Garden Grove formally amends the ordinance, design to the current 6 ft standard between your ADU and other structures.
Match the primary home's exterior materials if going custom. A fully custom attached or detached ADU must match the primary dwelling's roof, wall, and window/door colors and materials, unless you use a pre-approved ADU Go plan.
Keep new construction at or under 750 sq ft if avoiding impact fees matters to you. Larger units are charged proportionally to the primary dwelling's floor area.
Decide on rental plans before you build. Short-term rentals under 30 days are prohibited for both ADUs and JADUs, so this is long-term housing only.
FAQ
Common questions
Do I need to live on the property to build an ADU in Garden Grove?
No. California's AB 976 permanently eliminated owner-occupancy requirements for standard ADUs statewide as of January 1, 2024. A JADU still requires the owner to occupy either the JADU or the remaining primary home, backed by a recorded deed restriction.
How many ADUs can I build on one lot?
On a single-family lot, 1 ADU plus 1 JADU. A lot with an existing multifamily building can add up to 8 detached ADUs (not exceeding the number of existing units) plus converted ADUs equal to up to 25% of existing units.
Do I need extra parking for an ADU?
Usually 1 space for a new attached or detached ADU, though it's waived within a half-mile of transit, in a historic district, for converted ADUs, and in a few other listed cases. JADUs never require additional parking.
How long does the permit process take?
The city must decide within 60 days of a complete application (30 days if you use a pre-approved ADU Go plan or an identical previously approved plan), with no discretionary hearing. An application not acted on in time is automatically approved.
What's the maximum size for a detached ADU in Garden Grove?
850 sq ft for a studio or 1-bedroom unit, or 1,200 sq ft for a 2-bedroom or larger unit, with a 16 ft height limit (up to 18 ft on qualifying multifamily or transit-proximate lots).
How much does an ADU cost to build in Garden Grove?
Garage conversions tend to run roughly $70,000-$180,000, and new detached units roughly $150,000-$340,000 or more, based on local contractor estimates and regional reporting. Permit fees are reported at roughly $5,000-$25,000 depending on project scope.
What is ADU Go?
ADU Go is Garden Grove's free pre-approved ADU plan program: four city-owned designs ranging from a 447 sq ft studio to a 1,000 sq ft three-bedroom. Using one skips the architectural-compatibility review, though you still need site-specific documents like a site plan, Title 24 compliance, and structural calculations.
Is Garden Grove's ADU ordinance fully compliant with state law?
Not entirely as of this writing. A March 2026 HCD review of Ordinance No. 2966 (adopted August 2025) found a dozen provisions that still needed adjustment, including the 6 ft building-separation rule and a mandatory design-matching requirement, and gave the city until April 29, 2026 to respond. Confirm the current status of any resulting amendment with Garden Grove Planning Services.
