Union City, CA Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Union City, CA, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Eligible structures
- Attached and detached garages
- Replacement parking
- Not required
- Demolition permit
- Issued with ADU permit
- Review
- Ministerial, no hearing
Summary
Union City's ADU ordinance lets homeowners convert an attached or detached garage into an accessory dwelling unit, waiving replacement parking and combining the garage demolition permit with the ADU permit review.
ADUs shall be either attached to, or located within, the proposed or existing primary dwelling, including attached garages, storage areas or similar uses or an accessory structure or detached from the proposed or existing primary dwelling and located on the same lot as the proposed or existing primary dwelling, including detached garages. ... replacement parking shall not be required when a garage, carport, covered parking structure, or uncovered parking space is demolished in conjunction with the construction of an ADU or converted to an ADU.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4940544; v16 updated 2026-06-23).
Full Breakdown
Union City's ADU ordinance (Union City Municipal Code § 18.34.030(B)) expressly allows converting an attached or detached garage into an ADU: garages are listed alongside storage areas and accessory structures as eligible ADU locations. Converting a garage relieves the owner of replacement parking: subsection (C)(5) states no replacement parking is required when a garage, carport, or parking space is demolished or converted for an ADU, and a garage demolition permit is reviewed and issued together with the ADU permit rather than as a separate approval. State ADU law, Government Code Sections 66310-66342, sets the floor these local rules must meet.
Violations & Fines
Converting a garage without a building permit, or without meeting the ministerial ADU permit requirements of § 18.34.020, exposes the owner to a stop-work order and code enforcement action; no separate parking penalty applies since replacement parking is waived.
Frequently Asked Questions
Does converting a garage to an ADU require replacement parking?
Can I convert a detached garage to an ADU in Union City?
Sources & Official References
Other rules in Union City
California rules heatmap·Compare Union City to another location·View the California accessory structures overview
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Garage Conversions in Nearby Cities
How other cities in Alameda County handle garage conversions.