In short
- 663 ADU permits since 2018.
- 102 in 2025, down 15% from 2024.
- Typical permit time: 230 days from application to permit (median of 397 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 | 27 | — | — |
| 2019 | 30 | — | — |
| 2020 | 11 | 4 | 0 |
| 2021 | 87 | — | — |
| 2022 | 132 | — | — |
| 2023 | 154 | — | — |
| 2024 | 120 | — | — |
| 2025 | 102 | — | — |
“—” means the source for that year does not report ADU type.
Read more: ADU types explained
ADU rules in Alhambra
State law check: No HCD review letter on file (that isn't a finding either way). The code's junior-ADU owner rule covers every junior ADU, stricter than current state law.
| Rule | Alhambra's code | State law guarantees |
|---|---|---|
| Maximum size | Detached: 1,200 sq ft. Attached: 50% of the house, or 850 sq ft (1 bedroom or less) / 1,000 sq ft (more), whichever is greater. Conversions have no cap. 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 | Two stories and 25 ft, attached or detached. | 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; none for conversions. An ADU in front of the house keeps the zone's front setback. 5 ft between buildings, eave to eave. | No more than 4 ft side and rear; none for conversions of existing space. |
| Parking | 1 space (tandem on the driveway is fine) unless exempt: within ½ mile of public transit, inside the house or an existing accessory structure, historic sites and others. None for junior ADUs; 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. 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 attached or detached ADU, one ADU converted from existing space 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 of ADUs or junior ADUs. | No guarantee: cities may require rentals of more than 30 days, and junior ADUs can't be short-term rentals. |
- ADUs over 800 sq ft count toward the zone's floor area, lot coverage and open space limits.
- Design: a locally regulated ADU must match the house's materials, roof, colors and details, unless it uses a city pre-approved plan.
- No separate Planning application: ADUs go through the building permit.
Where local rules conflict with state law, state law controls. Sources: Alhambra Municipal Code § 23.22.040 (Ord. 4844, Apr 28, 2025) · Alhambra ADU Informational Handout (Dec 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 |
|---|---|---|---|
| Garage conversion | not reported | ||
| Unclassified | 230 | 154 – 347 | 397 |
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 348 ADU permits Alhambra reported issuing from 2020 through 2023, 256 (74%) have a completion reported to the state. For those, the median time from permit to completion was 13 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 Alhambra? Feature your business on this page.
Questions about ADUs in Alhambra
How many ADUs have been permitted in Alhambra?
Public records show 663 ADU permits in Alhambra from 2018 through 2025. 102 in 2025, down 15% 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 Alhambra?
Among the 397 ADU permits in Alhambra with both dates recorded, half were issued within 230 days of the application; the middle half took 154 to 347 days. That includes plan-check corrections and resubmittals, not just the review itself.
Can I build an ADU on my property in Alhambra?
California law allows ADUs on most lots with a house, including in Alhambra, 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 Alhambra?
Apply with the City of Alhambra's Planning Division through the city's online Permit Portal; no separate Planning application is needed. 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.