Union City, CA Building Setbacks & Zoning: Lot Coverage Limits (2026)
Key Facts
- RS districts (single-family)
- 50% maximum coverage
- RM 3500 / RM 2500
- 70% maximum coverage
- RM 1500
- 80% maximum coverage
- Governing section
- § 18.32.080
Summary
Union City limits building lot coverage to 50% of site area in all RS single-family zoning districts, rising to 70% in RM 3500/2500 and 80% in RM 1500 multifamily districts, under Alameda County, California zoning code.
The maximum site area covered by all structures located on the site shall be as prescribed in the following table: RS 10000, 50%. RS 8000, 50%. RS 7000, 50%. RS 6000, 50%. RS 4500, 50%. RM 3500, 70%. RM 2500, 70%. RM 1500, 80%.
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
Municipal Code § 18.32.080 sets maximum lot coverage, the share of a site's area covered by structures, by residential district: all five RS (single-family) districts, from RS 10000 down to RS 4500, cap coverage at 50%. Multifamily RM districts allow more: RM 3500 and RM 2500 top out at 70%, and RM 1500 allows up to 80%. These figures apply citywide in Union City's standard residential zones; the separate R-5000 district (§ 18.88.080) and the Open Space district (§ 18.92.080, capped at 6%) set their own distinct coverage limits.
Violations & Fines
Exceeding the maximum lot coverage without an approved variance triggers plan-check rejection or a stop-work order, and the excess structure becomes nonconforming and subject to removal under § 18.16.
Frequently Asked Questions
What's the maximum lot coverage for a single-family home in Union City?
Are lot coverage limits higher for multifamily lots?
Sources & Official References
Other rules in Union City
California rules heatmap·Compare Union City to another location·View the California building setbacks & zoning overview
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Lot Coverage Limits in Nearby Cities
How other cities in Alameda County handle lot coverage limits.