Union City — Development Standards

Last reviewed: July 2, 2026

Overview

This page summarizes what the Union City Zoning Ordinance (Title 18) actually says about development standards — setbacks, heights, lot coverage, density and FAR — and explains how those rules differ by district. It cites the controlling code sections and shows where to go next for related rules (for example, parking, design review, overlay districts, and ADUs) so you can verify parcel-specific requirements. All numeric limits below are drawn from the Union City zoning code; where the code is silent I note that explicitly. See the code chapters cited for full legal text (bolded code names and numbers and § citations are provided inline). Links below point to related City topics you will commonly need.

• When you see parking the first time it links to the city's parking page: parking.
• When you see design review the first time it links to the city's design review page: design review.
• When you see overlay districts the first time it links to the overlay page: overlay districts.
• When you see ADUs the first time it links to the ADU page: ADUs.
• When you see California Building Standards Code the first time it links to the state building-code page: California Building Standards Code.
• When you see landscaping the first time it links to the landscaping page: landscaping.
• When you see signage the first time it links to the signage page: signage.
• When you see nonconforming uses the first time it links to the nonconforming uses page: nonconforming uses.

All standards below are taken from the Union City Zoning Ordinance (Title 18). Citations show the code section(s) and the file search reference to the ordinance material used.

District-by-district development standards

Notes on citation style used below: each numeric rule is followed by the controlling code section range (with a § glyph) and the file-search citation that contains that section text.

R-5000 (R‑5000 Zoning District)

Purpose & where it applies

• The R-5000 district is separately codified to regulate older Decoto single‑family areas and defines lot size, setbacks, parking and height tailored to those neighborhoods. § 18.88.010 – § 18.88.130 .

Typical permitted uses

• One-family dwellings and accessory structures; ADUs are allowed subject to Chapter 18.34. § 18.88.010 – § 18.88.130 .

Key dimensional standards (plain-English)

• Minimum lot size / building site: 5,000 sq ft (typical building site) and 50 ft width, with limited exceptions for very old lots; see § 18.88.010 – § 18.88.130 .
• Front setback for single-family: 20 ft minimum, with limited reduction options; side yard typically 5 ft (10 ft on a street/alley); rear yard 10 ft. § 18.88.010 – § 18.88.130 and cross‑references to Chapter 18.32 .
• Height: no more than two stories or 30 ft (whichever is less) for one‑family dwellings. § 18.88.010 – § 18.88.130 .
• Parking: new SFRs in R‑5000 must provide two covered, enclosed spaces; existing SFRs must maintain at least one such space. § 18.88.010 – § 18.88.130 .

Practical note: the R‑5000 chapter tells you to default to the general residential rules in Chapter 18.32 when a topic isn’t covered in R‑5000 — always check both. § 18.88.010 – § 18.88.130 .

RS and RM residential districts (Chapter 18.32)

Purpose & where it applies

• The RS (several RS flavors: RS 10000, RS 8000, RS 7000, RS 6000, RS 4500) and RM (e.g., RM 3500, RM 2500, RM 1500) districts are regulated in Chapter 18.32. § 18.32.010 – § 18.32.190 .

Typical permitted uses

• RS: single‑family dwellings and accessory uses; RM: multifamily dwellings, semi‑detached and attached units; ADUs permitted per Chapter 18.34. § 18.32.010 – § 18.32.190 .

Key dimensional standards (district highlights)

• Lot width & depth minima vary by district (example: RS 10000 inside lot 80 ft width; RM 1500 inside lot 60 ft width) — see the table in § 18.32 for full list. § 18.32.010 – § 18.32.190 .
• Lot coverage maximums: RS districts generally 50%; RM 1500 up to 80%; RM 2500/3500 typically 70%. § 18.32.010 – § 18.32.190 .
• Front setbacks: RS districts usually 20 ft (but RS 10000 and RS 8000: 25 ft); RM districts: 10 ft. § 18.32.010 – § 18.32.190 .
• Side yards: residential side yard is typically 10% of lot width (with minimums and maximums described); interior side yards providing access or parking are subject to higher minimums (e.g., 12 ft where providing vehicle access). § 18.32.010 – § 18.32.190 .
• Height: RS base max 30 ft; RM 2500/3500 max 45 ft; RM 1500 max 75 ft. § 18.32.010 – § 18.32.190 .
• Density (site area per unit): RM 3500 = 3,500 sf/unit; RM 2500 = 2,500 sf/unit; RM 1500 = ~1,450 sf/unit (subject to HE overlay). § 18.32.010 – § 18.32.190 .

Practical note: decks, garages, and other projections have specific setback/height rules (see Chapter 18.32) and landscaping/screening requirements should be planned early; the first line of applicable rules is Chapter 18.32. § 18.32.010 – § 18.32.190 . For landscaping see landscaping.

Community Commercial (CC) and Specialty Commercial (CS)

Purpose & typical uses

• CC (Community Commercial) governs neighborhood-commercial corridors and mixed-use sites; CS covers specialty commercial. Mixed-use along Mission Boulevard is explicitly regulated by CC standards and residential units above commerce use RM 1500 standards for density and parking. § 18.36 (various) and cross‑references in the code; see the mixed‑use Mission Boulevard provision.

Key dimensional standards (high level)

• Mixed‑use residential above ground‑floor commercial uses must apply CC lot, setback and height standards for the commercial portion and RM 1500 rules for residential density/parking. § 18.36.xx and cross-reference to § 18.32 for RM 1500 standards .
• Parking minimums for commercial uses are in Chapter 18.36 (and cross‑reference to the city's parking standards). See parking. § 18.36.150 .

Verify exact CC dimensional numbers on the site-level table because special‑plan or Old Alvarado rules may modify setbacks and lot coverage. § 18.36 and mission‑boulevard mixed‑use rules .

Corridor Mixed‑Use Employment (CMUE) and Station East Employment (SEE) — Table 18.41.060

Purpose & where it applies

• CMUE and SEE are employment/employment‑mixed districts with specific FAR, lot dimensions and height bands listed in Table 18.41.060. Table 18.41.060 / § 18.41.060 .

Key dimensional standards (decision‑relevant excerpts)

• Site area, minimum: 1 acre (both CMUE and SEE). § 18.41.060 .
• FAR (floor area ratio): CMUE minimum 0.40, maximum 2.0; SEE minimum 0.75, maximum 3.0. § 18.41.060 .
• Street frontage & lot depth minimums: 150 ft frontage, 200 ft depth (exceptions possible via site development review). § 18.41.060 .
• Setbacks: typical 10 ft front, interior side 4–5 ft (but much larger when adjoining residential: 50 ft for CMUE adjoining residential; 20 ft for SEE). § 18.41.060 .
• Maximum height: 60 ft (CMUE) and 100 ft (SEE) with rooftop amenity allowances; buildings above certain heights require use permits. § 18.41.060 .

Practical note: the tables are prescriptive — for higher heights or to reduce setbacks the decision maker must make findings or approval via use permit/site development review. Also all development must comply with § 18.24.050 (bulk regulations) as cross‑referenced. .

Station East Mixed‑Use Residential (SEMU‑R)

Purpose & typical uses

• SEMU‑R is focused on high‑density residential with ground‑floor commercial along major thoroughfares, codified in Chapter 18.37. § 18.37.010 – § 18.37.210 .

Key dimensional standards

• Allowed FAR range for the district and specific minimums/maximums are stated in the district regulations (includes such items as minimum site area per unit in plan tables). § 18.37.010 – § 18.37.210 .
• Setbacks: front/side/rear minimum setbacks 6 ft generally; buildings fronting Decoto Road or Alvarado‑Niles Road require 20 ft setbacks (may be reduced to 10 ft for up to 10% of frontage with site development review). § 18.37.010 – § 18.37.210 .
• Height: district maximum is 100 ft; rooftop amenities allowed (with caps). § 18.37.010 – § 18.37.210 .
• FAR and density ranges are established; for mixed‑use, nonresidential FAR minimums are sometimes required except for live/work units (see district text). § 18.37.010 – § 18.37.210 .

Practical note: SEMU‑R explicitly requires compliance with § 18.24.050 and various design rules; expect design review and site development review for projects at the taller end. See design review. .

Open Space (OS)

Purpose & standards

• OS protects park/open space lands and sets large setbacks and very low coverage: see Table 18.92.070 and Chapter 18.92. § 18.92.010 – § 18.92.200 and Table 18.92.070. .

Key standards

• Front / side / rear setbacks: up to 100 ft on large parcels; smaller public lands and sites under 10 acres have lower minima (see Table 18.92.070). § 18.92.070 .
• Maximum impervious area / building coverage: 6% (very low). § 18.92.070 .
• Height: residential buildings not to exceed two stories or 25 ft (varies by OS sub‑designation). § 18.92.070 .

511 Area, Decoto Industrial Park Study Area (special districts)

• The 511 Area and DIPSA (Decoto Industrial Park Study Area) have their own tables and special standards; see Chapter 18.100 (511 Area) and Chapter 18.102 (DIPSA) for site area, setbacks, buffering (e.g., 100 ft powerline buffer), and other project‑level conditions. § 18.100.050 and § 18.102.010 – § 18.102.050 .

Quick decision table (most used standards)

(Reference: tables and district chapters cited above; always confirm the parcel’s specific zoning and any overlay that modifies these numbers.)

Checklist

• Confirm property zoning and any overlay districts (e.g., HE overlay, LHP) that modify base standards. § 18.116 / § 18.106
• Pull the district chapter for the parcel and read the district table(s) (e.g., Chapter 18.32, 18.37, 18.41, 18.88, 18.92). § 18.32, § 18.37, § 18.41, § 18.88, § 18.92
• Verify required FAR, maximum height, minimum lot area or frontage for your district (district tables cited above). Table 18.41.060, Chapter 18.32
• Confirm parking minimums and bicycle parking requirements (Chapter 18.28/18.32/18.36). See parking. § 18.32.160 / § 18.36.150
• Check whether proposed height increases or setback modifications require a use permit, site development review, or variance. See § 18.56, § 18.60, and site development chapters.
• Confirm landscaping/screening and solid‑waste enclosure placement early — these are commonly required conditions. See landscaping and Chapter 18.92.
• For ADUs, consult Chapter 18.34 and state ADU law (California ADU law). § 18.34 (not quoted here)
• If the property is historic or in an LHP overlay, confirm design review triggers. See design review and Chapter 18.106.

Risks & Ambiguities

Plain-English Summary

Union City’s zoning code sets different development rules for each zoning district: single‑family zones (R‑5000, RS) emphasize lot size, modest heights (30 ft) and 50% coverage; multifamily RM zones allow denser development and taller buildings (RM 1500 up to 75 ft and high coverage); employment and mixed‑use zones (CMUE, SEE, SEMU‑R) specify FAR ranges, larger lot/ frontages and taller height caps (up to 100–160 ft in some areas) and require larger buffers next to residences. Always read the parcel’s district chapter and the cross‑referenced chapters (notably Chapter 18.32 and Table 18.41.060) because overlays and site‑specific plans can change the numbers. § 18.32, § 18.41.060, § 18.37.010 – § 18.37.210.

Source References

• Title 18 Zoning — Union City Zoning Code (general): § 18.04.010 – § 18.04.210
• Chapter 18.32 — Residential Districts (RS/RM standards, setbacks, coverage, heights): § 18.32.010 – § 18.32.190
• Chapter 18.88 — R‑5000 Zoning District: § 18.88.010 – § 18.88.130
• Table 18.41.060 — CMUE / SEE development standards (FAR, frontage, setbacks, height): § 18.41.060
• Chapter 18.37 — Station East Mixed‑Use Residential (SEMU‑R): § 18.37.010 – § 18.37.210
• Chapter 18.92 — Open Space (OS) district and Table 18.92.070: § 18.92.010 – § 18.92.200 and Table 18.92.070
• Chapter 18.100 — 511 Area (standards and specific plan table references): Table 18.100.050
• Chapter 18.102 — Decoto Industrial Park Study Area (DIPSA): § 18.102.010 – § 18.102.050
• Parking cross‑references: § 18.32.160, § 18.36.150 (off‑street parking requirements referenced in multiple district chapters; see parking).
• SB 9 rules and objective standards: Chapter 18.31 (§ 18.31.010 – § 18.31.110) for SB 9 limitations and setbacks.

If you need the full ordinance PDF or the city’s eCode page for a parcel, tell me the address or APN and I will point to the exact chapter and table that controls that property. For construction details and Title 24 compliance, consult the California Building Standards Code.

Retrieved passages

• Union City Zoning Code (§ 4) High relevance show source text
• Union City Zoning Code (Section 18.52.060) High relevance show source text
• Union City Zoning Code (§ 2) High relevance show source text
• Union City Zoning Code (§ 2) High relevance show source text
• Union City Zoning Code (§ 5) High relevance show source text
• Union City Zoning Code (§ 2) High relevance show source text
• Union City Zoning Code (§ 2) High relevance show source text
• Union City Zoning Code (§ 2) High relevance show source text
• CBC § 4 (§ 4) High relevance show source text
• Union City Zoning Code High relevance show source text
• Union City Zoning Code (§ 2) High relevance show source text
• Union City Zoning Code (§ 3) High relevance show source text
• Union City Zoning Code (Chapter 18.112) Medium relevance show source text

Cited sections

• Title 18 Zoning — Union City Zoning Code (general): **§ 18.04.010 – § 18.04.210** (Title 18)
• Chapter 18.32 — Residential Districts (RS/RM standards, setbacks, coverage, heights): **§ 18.32.010 – § 18.32.190** (Chapter 18.32)
• Chapter 18.88 — R‑5000 Zoning District: **§ 18.88.010 – § 18.88.130** (Chapter 18.88)
• Table 18.41.060 — CMUE / SEE development standards (FAR, frontage, setbacks, height): **§ 18.41.060** (§ 18.41.060)
• Chapter 18.37 — Station East Mixed‑Use Residential (SEMU‑R): **§ 18.37.010 – § 18.37.210** (Chapter 18.37)
• Chapter 18.92 — Open Space (OS) district and Table 18.92.070: **§ 18.92.010 – § 18.92.200** and **Table 18.92.070** (Chapter 18.92)
• Chapter 18.100 — 511 Area (standards and specific plan table references): **Table 18.100.050** (Chapter 18.100)
• Chapter 18.102 — Decoto Industrial Park Study Area (DIPSA): **§ 18.102.010 – § 18.102.050** (Chapter 18.102)
• Parking cross‑references: **§ 18.32.160**, **§ 18.36.150** (off‑street parking requirements referenced in multiple district chapters; see parking). (§ 18.32.160)
• SB 9 rules and objective standards: **Chapter 18.31** (§ 18.31.010 – § 18.31.110) for SB 9 limitations and setbacks. (Chapter 18.31)
• UnionCity_ZoningCode.md

• Official Union City code library