In short
- 2,578 ADU permits since 2018.
- 445 in 2025, down 1% from 2024.
- Typical permit time: 128 days from application to permit (median of 1,462 permits with both dates recorded).
About this data
- Source: California HCD Housing Element Annual Progress Reports. The state data does not say whether an ADU is detached, attached, a garage conversion or a JADU, so most records show as 'unknown'. Permit valuations are not published in this source. Timelines use the application date the city reported to the state, matched to the permit where possible; some cities report their planning application date, so timelines can include planning review. Each project is counted once, in its building-permit year (or completion year when no permit date was reported).
Permits by year
Permits by year and type (table)
| Year | All ADU permits | Garage conversions | Detached |
|---|---|---|---|
| 2018 | 90 | — | — |
| 2019 | 266 | — | — |
| 2020 | 266 | — | — |
| 2021 | 267 | — | — |
| 2022 | 374 | — | — |
| 2023 | 422 | 0 | 0 |
| 2024 | 448 | 33 | 257 |
| 2025 | 445 | 0 | 0 |
“—” means the source for that year does not report ADU type.
Read more: ADU types explained
ADU rules in Garden Grove
State law check: HCD found the city's ADU ordinance (August 12, 2025) out of line with state law (March 30, 2026), including its minimum sizes, front setbacks, building separation and ADU garages; state law controls where they differ.
| Rule | Garden Grove's code | State law guarantees |
|---|---|---|
| Maximum size | Attached: 850 sq ft (studio or 1 bedroom) or 1,200 sq ft (2+ bedrooms), or 50% of the house if less (at least 800 sq ft). Detached: 850 or 1,200 sq ft. No cap for conversions. Minimum 150 to 700 sq ft by bedroom count. Junior ADU 500 sq ft. | At least 850 sq ft (1,000 sq ft with 2+ bedrooms) must be allowed; an 800 sq ft detached ADU always is. Conversions of existing space have no size cap. Junior ADU: up to 500 sq ft. |
| Height | Detached: 16 ft (18 ft near transit, plus 2 ft for roof pitch). Attached: 25 ft or the zone limit, 2 stories. | Detached: at least 16 ft (18 ft within ½ mile of transit, plus 2 ft for a matching roof). Attached: 25 ft or the zone's limit, whichever is lower. |
| Setbacks | 4 ft side and rear; front setback matches the zone, unless that would block an 800 sq ft ADU. 6 ft between a detached ADU and other buildings. None for conversions. | No more than 4 ft side and rear; none for conversions of existing space. |
| Parking | 1 space for a new attached or detached ADU unless exempt (transit, historic district, car share); none for conversions. No replacement parking for converted garages. | At most 1 space; none within ½ mile of transit and in several other cases. No replacement parking when a garage is converted. |
| Owner living on site | None for ADUs. Junior ADU: the owner lives in the house or the junior ADU, with a deed restriction. | None for ADUs. A junior ADU that shares a bathroom with the house requires the owner to live in one of them. |
| How many on a single-family lot | One ADU and one junior ADU on a single-family lot, unless state law allows more. | One ADU converted from existing space, one junior ADU and one new detached ADU (up to 800 sq ft). From January 1, 2027: two new detached ADUs (a city then needn't allow a junior ADU on that lot). |
| Short-term rentals | 30 days or longer, for ADUs and junior ADUs. | No guarantee: cities may require rentals of more than 30 days, and junior ADUs can't be short-term rentals. |
- New ADUs must match the house's roof, walls, windows and colors, except state-law ADUs.
- An ADU needs its own water heater and washer and dryer hookups.
- The city runs ADU Go, a pre-approved ADU plan program; pre-approved plans are reviewed within 30 days.
Where local rules conflict with state law, state law controls. Sources: Garden Grove Municipal Code 9.54 · HCD findings (March 30, 2026); HCD's list of review letters; California ADU rules. Verified Oct 5, 2026. Rules change and every lot is different: confirm with the city before you design.
How long permits take
| Type | Median days, application to permit | Middle half | Permits |
|---|---|---|---|
| Detached ADU | 124 | 83 – 185 | 148 |
| Attached ADU | 109 | 92 – 164 | 26 |
| Garage conversion | 155 | 108 – 239 | 21 |
| Junior ADU (JADU) | 118 | 6 – 178 | 90 |
| Unclassified | 130 | 85 – 191 | 1,177 |
Middle half: the range covering the middle 50% of permits (a quarter were lower, a quarter higher).
Read more: How long ADUs take to build
From permit to completion
Of the 1,312 ADU permits Garden Grove reported issuing from 2020 through 2023, 956 (73%) have a completion reported to the state. For those, the median time from permit to completion was 9 months.
The state reports don't record expired or cancelled permits, and a completion the city hasn't reported looks the same as an unfinished project, so the share is a floor. Years with incomplete reports are left out.
What neighbors declared as cost
Cost data (declared permit valuations) is not published for this area in these sources.
Read more: How to choose an ADU builder
An ADU builder serving Garden Grove? Feature your business on this page.
Questions about ADUs in Garden Grove
How many ADUs have been permitted in Garden Grove?
Public records show 2,578 ADU permits in Garden Grove from 2018 through 2025. 445 in 2025, down 1% from 2024. These counts come from the city's reports to the state, which place a project in its completion year when no permit date was reported.
How long does an ADU permit take in Garden Grove?
Among the 1,462 ADU permits in Garden Grove with both dates recorded, half were issued within 128 days of the application; the middle half took 84 to 190 days. That includes plan-check corrections and resubmittals, not just the review itself.
Can I build an ADU on my property in Garden Grove?
California law allows ADUs on most lots with a house, including in Garden Grove, but what you can build depends on your lot, local rules and utilities. This site shows permits, not eligibility. See California ADU rules.
Where do I apply for an ADU permit in Garden Grove?
Apply with the City of Garden Grove's Community Development Department, which runs ADU Go, a pre-approved ADU plan program. Official ADU page.
How current is this?
- State annual progress reports: through 2025 (published once a year)
How our data works · Download the data · Free to reuse with credit to SoCal ADU Tracker (socaladutracker.com), under CC BY 4.0.