Building an ADU in Garden Grove

Which rules apply in Garden Grove

Garden Grove's ADU and junior ADU rules are in Chapter 9.54 of the Garden Grove Municipal Code, last amended by Ordinance No. 2966 on August 12, 2025. The chapter says its provisions "shall be interpreted to be consistent with" state ADU law (Gov. Code 66310 and following) "and shall be applied in a manner that is consistent with state law," and that the city won't apply any of its standards "to the extent prohibited by any provision of state law, including, but not limited to, Government Code Section 66323."

ADUs are allowed on any lot zoned for single-family or multifamily homes that has an existing or proposed home. JADUs are allowed inside a single-family house on single-family-zoned lots. The Director of Community Development approves or denies a complete application "ministerially without discretionary review or public hearing."

Start at the city's ADU page, which links the code, the application, handouts and the ADU Go plans. [1][4]

What the state flagged in 2026

On March 30, 2026, HCD sent the city a letter finding that Ordinance No. 2966 "fails to comply with State ADU Laws" and gave the city until April 29, 2026 to respond. Among the findings:

• The code doesn't allow a converted ADU inside a proposed (not yet built) house.
• Minimum ADU sizes by bedroom count can't be applied to the state's by-right ADUs.
• The front setback rule must allow an ADU of at least 800 sq ft with 4-foot side and rear setbacks.
• The 20-foot setback for a new ADU garage must not get in the way of building ADUs; the 6-foot building separation can't be applied to the state's by-right ADUs beyond what fire and safety require; and the parking rule leaves out state exemptions.
• The "consistency and compatibility of design" language is not objective, and the mechanical equipment screening and 3-foot clear path rules must go.
• The city can't require JADU parking, and can't require a new utility connection for converted ADUs.

The city's online code, current through Ordinance No. 2979 (August 11, 2026), still shows the 2025 text. Under state law the city must either amend the ordinance or adopt findings explaining why it believes the ordinance complies. Where your project touches one of these points, confirm with the Planning Division at (714) 741-5312 how the city is applying the rule. [1][2][5]

How many units you can build

On a single-family lot, the code says "Except as otherwise provided in Government Code Section 66323, no more than one ADU and/or one JADU is permitted." The JADU deed restriction also states that "The property shall include no more than one JADU and/or ADU."

HCD's handbook says the state's by-right categories must be allowed together: on a single-family lot, "at least one ADU constructed from existing space, one JADU, and one newly constructed detached ADU." Because the city code defers to Section 66323, ask Planning how it handles that combination before you design.

On multifamily lots the code allows up to eight detached ADUs on a lot with existing apartments (no more than the number of existing units), up to two detached ADUs with a proposed apartment building, and converted ADUs in non-living space up to 25% of the existing units (at least one). [1][6]

Size, height and setbacks

• Detached ADU: up to 850 sq ft for a studio or one bedroom, 1,200 sq ft for two or more bedrooms.
• Attached ADU: the same caps or 50% of the house's floor area, whichever is less; if the house is under 1,600 sq ft, up to 800 sq ft. HCD's handbook says a percentage limit on attached ADUs can't restrict an ADU to less than 850 sq ft, or 1,000 sq ft with more than one bedroom.
• Minimum sizes: 150 sq ft (efficiency unit), 220 (studio), 500 (one bedroom), 700 (two or more). HCD says these can't apply to the state's by-right ADUs.
• Converted ADU: no size cap if you don't add floor area; a converted accessory structure can add up to 150 sq ft for entry and exit.
• Extras: a covered porch or patio up to 80 sq ft and an attached one-car garage up to 250 sq ft, with a combined total of no more than 1,530 sq ft.
• Height: a detached ADU 16 feet; 18 feet on a lot with a multistory apartment building or within a half-mile walk of a major transit stop or high-quality transit corridor (plus up to 2 feet for a roof pitch matching the house near transit). An attached ADU 25 feet or the house's height limit, whichever is lower, and no more than two stories. Converted ADUs have no height limit.
• Setbacks: 4 feet from side and rear lot lines. The zone's front setback applies, but part of an ADU may go in the front setback only as far as needed to fit an ADU of up to 800 sq ft. No setbacks for converted ADUs if the existing setbacks are enough for fire safety.
• Separation: 6 feet between a detached ADU and the house, and between an ADU and other unattached buildings, except conversions without added floor area.
• ADU garage: 20 feet from a street or alley it opens onto.

The code also says floor area, front setback, building separation, lot coverage, open space and minimum lot size rules are waived as needed to allow an ADU of up to 800 sq ft. State law says the state's by-right ADUs don't have to meet lot coverage, front setbacks and design standards. Confirm with Planning how the city applies these limits to your lot. [1][2][6]

Design and other building requirements

Except as Government Code 66323 provides, an attached or detached ADU must match the house: the roof type, pitch, color, material, texture and eaves, and the color, material and texture of walls, windows and doors. ADUs built from a city pre-approved plan are deemed to comply.

The code also requires:

• separate exterior access for an attached or converted ADU;
• a laundry space with washer and dryer hookups in the ADU or in a garage it can reach;
• a separate water heater inside the unit (no exterior water heater enclosures; tankless is fine);
• roof and ground equipment and meters "completely screened from view," with a 3-foot clear path if placed between a building and the property line; and
• trash container areas of at least 38 by 38 inches each, paved and outside the garage parking area.

HCD's 2026 letter says the screening and 3-foot path rules and the "consistency and compatibility of design" language don't comply with state law. Ask Planning how these apply to your plans. [1][2]

Parking

A new attached or detached ADU needs one off-street space on top of the house's parking. It can be in a setback area or tandem on the driveway unless the Director finds that isn't feasible. If you demolish or convert a garage, carport or parking space for the ADU, you don't have to replace it.

No ADU parking is required when the ADU is within a half-mile walk of public transit, in an architecturally and historically significant historic district, part of the house or an accessory structure (a converted ADU), where on-street parking permits are required but not offered to the occupant, or within one block of a car-share vehicle.

State law adds one more exemption the city code doesn't list: an ADU applied for together with a new home on the lot, if the ADU or lot also meets one of the other exemptions. State law also bars parking requirements for the state's by-right ADUs, and HCD flagged the city's parking rule in 2026. Confirm with Planning before you plan a parking space. [1][2][6]

Fees

The code says ADUs are subject to the city's development impact fees, but "No impact fee as required by this Code is required for an ADU that is less than 750 square feet in size," and any impact fee on an ADU of 750 sq ft or more is charged in proportion to the house's size. "Impact fee" here doesn't include utility connection fees or capacity charges, planning application fees, plan check fees or building permit fees.

The city's Public Works developer fee sheet, which says its amounts are "as of 1/1/2020 and are subject to change," lists for ADUs 750 sq ft or larger: a park facility fee (flat rate $6,061), traffic mitigation (flat rate $1,600), drainage ($0.27 per sq ft of ADU) and a parkway tree fee ($2.50 per linear foot of front lot line). It says only the Orange County Sanitation District fee ($2,000 to $4,000, by number of bedrooms) applies to ADUs under 750 sq ft. Ask Public Works for current amounts and how the proportional rule is applied.

State law exempts ADUs of 750 sq ft of interior livable space "or less" from impact fees (the city code says "less than 750"), and school districts can charge only ADUs over 500 sq ft. For typical costs see our ADU cost guide. [1][4][6][7]

Junior ADUs

A JADU is up to 500 sq ft and built only within the walls of a proposed or existing single-family house, including an existing attached garage. It needs a separate entrance and an efficiency kitchen. It may have its own bathroom or share the house's; without its own, it needs an interior entrance to the main living area or direct access to the shared bathroom. It uses the house's water, sewer and other utility connections, with no separate meters.

Before the building permit is issued, you record a deed restriction with the County Recorder (city form) saying the JADU can't be sold, mortgaged or transferred separately and that an owner must live in the JADU or the rest of the house; if owner occupancy stops, the JADU "shall automatically become unhabitable space." The code says no extra JADU parking is required "beyond that required at the time the existing primary dwelling was constructed."

State law changed in 2026: owner occupancy may be required only if the JADU shares a bathroom with the house. HCD's handbook also says a JADU deed restriction includes only the ban on separate sale and the JADU's size and features. HCD's 2026 letter also says the city can't require any JADU parking. Ask Planning how these apply. See our junior ADU guide and garage conversion guide. [1][2][6]

Renting it out, sale and fire sprinklers

An ADU or JADU may be rented separately from the house, but any rental must be for 30 days or longer; short-term rentals are prohibited. Neither may be sold separately from the house except as Gov. Code 66341 allows. You don't have to live on the property to have an ADU.

Fire sprinklers aren't required in an ADU if the house doesn't need them, and building an ADU doesn't trigger sprinklers in the existing house. The city won't require you to fix nonconforming zoning conditions, building code violations or unpermitted structures that aren't a health and safety threat and aren't affected by the ADU. [1]

Permit steps in Garden Grove

1. Talk to the Planning Division

   Call Planning at (714) 741-5312 or visit 11222 Acacia Parkway to confirm the ADU complies with zoning before you submit. If you want to use an ADU Go plan, Planning is the first step. [3][5][8]

2. Get plans

   Download a free ADU Go plan and add the site plan, Title 24 and structural sheets, or have a designer prepare custom plans. [3]

3. Check sewer, utilities and flood zone

   Verify sewer capacity with the Water Services Division at (714) 741-5346, check easements and clearances to Southern California Edison lines, and meet flood-zone rules if the lot is in Zone A. [8]

4. Submit for plan check

   Submit the signed ADU application, building plan check application and a PDF plan set online; the ADU Go page sends pre-approved plan projects to GG Ready. The city's checklist (dated December 2022) says owners must sign an agreement pausing the 60-day review period while corrections are pending, and that refusing to sign leads to denial. State law pauses the 60-day period when the applicant asks for a delay; ask Planning whether the agreement is still required. [3][6][8]

5. Record the JADU deed restriction (JADUs only)

   Provide a grant deed or title report so the city can prepare the covenant, then record it with the County Recorder and file a copy with the city before the building permit is issued. [1][8]

6. Pay fees, get the permit and build

   Building and Safety invoices plan check and permit fees, and impact fees apply to ADUs of 750 sq ft or more. Questions go to Building and Safety at (714) 741-5307. [1][8]

Pre-approved and sample plans

• ADU Go (Pre-Approved ADU Program)

  Four free city-owned ADU plans (447 sq ft studio, 630 sq ft one-bedroom, 750 sq ft two-bedroom, 1,000 sq ft three-bedroom); architectural sheets only, not for Flood Zone A lots, submitted through GG Ready. [3]

Who to call

• City of Garden Grove Planning Services Division

  ADU zoning standards, ADU Go plans and the JADU deed restriction

  (714) 741-5312

  11222 Acacia Parkway, Garden Grove, CA 92840

  [5][8]

• City of Garden Grove Building and Safety Division

  Plan check and building permits

  (714) 741-5307

  11222 Acacia Parkway, Garden Grove, CA 92840

  [4][8]

• Garden Grove Water Services Division

  Sewer capacity verification for ADUs

  (714) 741-5346

  [8]

Questions people ask