Permit guides

ADU Permits in Union City: a Homeowner's Guide

Union City's ADU process is checklist-driven — and it has one requirement few other cities impose: undergrounded utilities.

Last updated October 2026. Rules change; always confirm current requirements with the city before you build.

Who handles your permit

ADU permits in Union City run through the Community Development Department — Planning Division for zoning, Building Division for the permit. The application rides on two city checklists: the ADU/JADU Zoning Checklist and the Design Standards Checklist, filed with the Building Division along with full plans.

What you can build

The standards Union City applies:

1,200 sq ftMax for a detached ADU

16 ftHeight limit for most detached ADUs

4 ftMinimum rear and side setbacks

1 + 1One ADU plus one Junior ADU per single-family lot

UndergroundUtility services to ADUs must be undergrounded

60 daysDeadline to act on a complete application

Hillside or environmentally sensitive areas can carry extra setback, height, or coverage limits. Sprinklers are required in the ADU when they're required for the main house.

Undergrounded utilities

This is Union City's signature requirement: utility services to ADUs must be undergrounded. Overhead drops that other cities accept won't pass here — budget for trenching and conduit from the start, because discovering it at plan check is an expensive redesign.

For Junior ADUs, the city requires a Declaration of Restrictions (deed restriction): signed by all owners, notarized, and recorded with the Alameda County Clerk. It ensures the JADU remains a secondary unit.

Price the trench early. Undergrounding is a real cost line — get the route and the utility's requirements confirmed before finalizing the budget.

What goes into the submittal

Union City expects a thorough package:

Completed ADU application to the Building Division
ADU/JADU Zoning Checklist and Design Standards Checklist
Building plans by a licensed architect or engineer: title sheet, scope of work, site plan, floor plans, elevations, sections, structural drawings
Stormwater checklist and landscape plan
Declaration of Restrictions for JADUs (notarized, recorded)

Where applications usually get stuck

Undergrounding costs. The trench, conduit, and utility coordination add thousands — plan for it upfront.
Hillside constraints. Special setback, height, or coverage limits can apply in hillside areas.
Deed restriction recording. The JADU restriction has to be signed, notarized, and recorded — a paperwork chain that stalls closings.
Sprinkler triggers. If the main house requires sprinklers, the ADU does too.

Not sure where to start? That's the part we do. We look at your property, map the requirements, coordinate the plans and specialists, and manage the submittal and corrections — one point of contact.

Tell us what you need help with.

Not sure where to start? That's what we're here for.

Send your project

Erik — (916) 540-8960 · Vall — (916) 956-8106
office@pcg-engineering.pro