In short
- 841 ADU permits since 2018.
- 148 in 2025, up 44% from 2024.
- Typical permit time: 300 days from application to permit (median of 372 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 | 48 | — | — |
| 2019 | 72 | — | — |
| 2020 | 44 | — | — |
| 2021 | 103 | — | — |
| 2022 | 195 | — | — |
| 2023 | 128 | — | — |
| 2024 | 103 | — | — |
| 2025 | 148 | — | — |
“—” means the source for that year does not report ADU type.
Read more: ADU types explained
Not counted above: 7 approved projects with no building permit reported yet.
ADU rules in Rosemead
State law check: HCD sent a technical-assistance letter (December 5, 2025) noting the city's 2020 ordinance on file may be outdated; no formal findings. The city responded.
| Rule | Rosemead's code | State law guarantees |
|---|---|---|
| Maximum size | Detached: 850 sq ft (studio or 1 bedroom) or 1,200 sq ft (2+ bedrooms), 800 sq ft with a junior ADU. Attached: 50% of the house (800 sq ft if the house is under 1,600). 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 | One story: 17 ft. Two stories: 30 ft. | 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; conversions need only fire-safety setbacks. 10 ft between dwellings. | No more than 4 ft side and rear; none for conversions of existing space. |
| Parking | 1 space per ADU or per bedroom, whichever is less, unless exempt; no replacement parking. | 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 permitted 2020–2024; the code lets the city require it after that. Junior ADU: required. | 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 converted ADU, or one detached ADU and one junior ADU. | 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 | No short-term rentals. | No guarantee: cities may require rentals of more than 30 days, and junior ADUs can't be short-term rentals. |
- City policy (March 4, 2025) caps a detached ADU at 1,200 sq ft including any attached garage, carport, patio or balcony.
- New ADUs must match or complement the house's design, colors and materials.
- The city has pre-approved detached ADU plans of 800, 1,000 and 1,200 sq ft.
Where local rules conflict with state law, state law controls. Sources: Rosemead Municipal Code § 17.30.190 (Ord. 995, Sep 8, 2020) · Rosemead ADU handout and Zoning Code Policy 25-01 (2026) · HCD letter (Dec 5, 2025); HCD's list of review letters; California ADU rules. Verified Sep 30, 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 |
|---|---|---|---|
| Unclassified | 300 | 196 – 448 | 372 |
Middle half: the range covering the middle 50% of permits (a quarter were lower, a quarter higher).
Read more: How long ADU permits take in Los Angeles (and other cities) · How long ADUs take to build
From permit to completion
Of the 410 ADU permits Rosemead reported issuing from 2020 through 2023, 225 (55%) have a completion reported to the state. For those, the median time from permit to completion was 12 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 Rosemead? Feature your business on this page.
Questions about ADUs in Rosemead
How many ADUs have been permitted in Rosemead?
Public records show 841 ADU permits in Rosemead from 2018 through 2025. 148 in 2025, up 44% 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 Rosemead?
Among the 372 ADU permits in Rosemead with both dates recorded, half were issued within 300 days of the application; the middle half took 196 to 448 days. That includes plan-check corrections and resubmittals, not just the review itself.
Can I build an ADU on my property in Rosemead?
California law allows ADUs on most lots with a house, including in Rosemead, 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 Rosemead?
Apply with the City of Rosemead's Planning Division, starting with an administrative site plan and design review before building plan check; the city lists pre-approved ADU plans. 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.