ADU Builder in Union City, CA
Get a Free Union City ADU Consultation
Union City ADU Design Standards
Union City’s ADU checklist (Municipal Code Chapter 18.34) includes design rules most cities do not have:
- No continuous wall plane longer than 15 feet.
- At least three exterior colors or materials.
- Roof pitch of at least 2.5:12, with eaves of at least 12 inches.
- No exterior stairs to an upper story, and no upper-floor balconies.
- A covered entry of at least 3 feet.
We design ADUs that meet these standards and still match the main house.
ADU Construction
Sizes, Setbacks and Utilities
- ADU up to 850 sq ft for a studio or one bedroom, 1,000 sq ft for two or more bedrooms. Junior ADU up to 500 sq ft, with owner occupancy and a recorded deed restriction.
- Detached ADUs generally 16 feet tall; attached ADUs follow the zoning district limit. We confirm current height rules for your lot.
- 4-foot side and rear setbacks, and 5 feet of separation from other structures.
- No parking required for the ADU. If a JADU is created in a garage, the lost parking must be replaced.
- A separate sewer lateral is required, and new detached ADUs need solar PV.
- Sprinklers only if the main house requires them.
Before submitting, the City asks ADU applicants to contact Alameda County Water District, Union Sanitary District and PG&E.
Pre-Approved ADU and Permits
Union City’s pre-approved ADU program lists plan PADU-25-001, a 700 sq ft unit with one bathroom.
34009 Alvarado-Niles Road, Union City, CA 94587 · City Hall (510) 471-3232
Building Division (510) 675-5313 · Planning (510) 675-5379
Building counter Monday to Thursday 9 a.m. to 5 p.m. and alternate Fridays 9 a.m. to noon. Planning counter Monday to Thursday 9 a.m. to 2 p.m., with appointments given priority. Plan submittals and resubmittals are taken at the counter.
Inspections are requested through the Building Inspection Hotline, (510) 487-0711. The City caps the number of inspections per day, so call early.
Explore More
Other Union City services: Bathrooms · Kitchens · Additions · New Homes · Union City overview
Same service nearby: Fremont · Newark · Alameda County
Union City ADU FAQ
What design rules apply to ADUs in Union City?
No wall plane over 15 feet, at least three exterior colors or materials, a 2.5:12 minimum roof pitch with 12-inch eaves, no exterior upper-story stairs or upper balconies, and a 3-foot covered entry.
How big can an ADU be in Union City?
850 sq ft for a studio or one bedroom and 1,000 sq ft for two or more. A junior ADU is up to 500 sq ft.
Does a Union City ADU need its own sewer line?
Yes, a separate sewer lateral is required.
Is there a pre-approved ADU plan?
Yes, PADU-25-001, a 700 sq ft unit.