Union City Zoning, Planning & Building Codes

Last reviewed: July 3, 2026

Overview

Union City’s land-use rules are codified in Title 18 — Zoning (the City of Union City Zoning Ordinance), which implements the General Plan and divides the city into districts that regulate allowable uses, bulk, parking and review procedures (§ 18.04.010 – § 18.04.210) . This page orients you to how the code is structured, the actual district families in use in Union City, where to find the citywide development standards, the main specific plans and overlays that alter base rules, how discretionary vs. ministerial review works, and how state housing rules (ADUs, SB 9, density and related law) have been folded into the local code.

How Union City's code is organized

• The zoning ordinance is titled Title 18 — Zoning and begins with general provisions and definitions (§ 18.04.010 – § 18.04.210) .
• The code is arranged by chapters that group rules by topic and district: e.g., Residential Districts (Chapter 18.32), Commercial Districts (Chapter 18.36), Industrial Districts (Chapter 18.40), bulk and general development rules (Chapter 18.24), parking/loading (Chapter 18.28), sign rules (Chapter 18.30), administration (Chapter 18.52) and the discretionary/administrative review procedures (Chapters 18.54, 18.56, 18.72, 18.76) .
• Where to look quickly:
  • Use the chapter headers: e.g., § 18.32.010 for residential district rules and § 18.36.010 for commercial rules .
  • Citywide bulk rules are in Chapter 18.24 (see § 18.24.010 – § 18.24.050) and special bulk rules or exceptions are cross‑referenced in district chapters .
  • Permits, decision-makers and appeal mechanics are in Chapter 18.52 (Administration) and the use-permit and variance chapters (Chapters 18.54, 18.56, 18.60) .

(If you want the city’s zoning menu view, see the Union City Zoning landing page.)

Zoning district families (what actually exists in Union City)

Union City uses a mix of conventional residential, commercial, industrial, mixed‑use and special district chapters. Key names and where they live in the code:

• Residential: R-5000 (R‑5000 district rules found at § 18.88.010 – § 18.88.130), and the city-wide RS and RM family within Chapter 18.32 (Residential Districts — § 18.32.010 – § 18.32.190) .
• Mixed‑use & Station/Transit districts: CMU (Corridor Mixed Use, Chapter 18.35), VMU (Village Mixed Use, § 18.27.010 – § 18.27.220), SEMU‑R (Station East Mixed Use Residential, § 18.37.010 – § 18.37.210) and the station mixed‑use commercial CSMU (Chapter 18.38) — these chapters explicitly allow ground-floor commercial with residential above and set district-specific rules .
• Commercial: CN (Neighborhood Commercial), CC (Community Commercial), CPA (Professional & Administrative), CVR (Visitor & Recreation), and CUL (Union Landing Commercial, Chapter 18.39) — rules in Chapter 18.36 (Commercial Districts, § 18.36.010 – § 18.36.210) and the Union Landing chapter govern permitted uses and conditional use tables .
• Industrial: ML (Light Industrial), MS (Special Industrial), MG and related industrial tables appear in Chapter 18.40 (Industrial Districts) with use tables and conditional permit designations .
• Open Space and Special Districts: OS — Open Space (Chapter 18.92); R‑5000 has its own chapter (18.88) for the historic Decoto area; 511 Area (Chapter 18.100) and DIPSA (Decoto Industrial Park Study Area, Chapter 18.102) are specific plan / special districts with their own standards .
• Overlays & combining districts: Hillside Combining (-H) (Chapter 18.96), Floodplain Combining (Chapter 18.98), Landmark & Historic Preservation (LHP, Chapter 18.106) and a Housing Element (HE) Overlay (Chapter 18.116) that implements density expectations under the Housing Element and State law (see § 18.116.010 – § 18.116.030) .

Bold district names above match the code language and each district chapter contains the specific permitted and conditional uses and cross‑references to code‑wide chapters.

Citywide development standards (high‑level)

Where the rules live and representative numbers:

• Bulk regulations and common yard/obstruction rules live in Chapter 18.24 (General Development Regulations); see § 18.24.010 – § 18.24.050 for how yards, obstructions and mandatory compliance work (and for the list of allowed encroachments such as roof overhangs, small terraces, pedestrian paths) .
• Representative residential minima (from the R‑5000 chapter):
  • Front setback: 20 ft (with limited exceptions) • Side setback: 5 ft • Rear setback: 10 ft • Height limit: 2 stories or 30 ft — see § 18.88.010 – § 18.88.130 for the full R‑5000 text .
• Station/Mixed‑use and employment districts set FAR, frontage and height ranges in their tables; for example CMUE / SEE development standards list FAR minimums (.40 / .75) and maximum FARs (2.0 / 3.0), front setbacks 10 ft, and maximum heights up to 60–100 ft depending on subdistrict — see Table 18.41.060 in the mixed‑use employment chapter for the full grid (Chapter 18.41 / § 18.41.060) .
• Parking: residential and commercial parking standards are cross‑referenced; the code points to residential parking requirements in § 18.32.160 and commercial parking in § 18.36.150 and allows decisions about shared parking and parking relief by the decision-maker in certain districts . The Station/Transit rules include specific lower parking minima for transit‑adjacent or BART property projects (see parking table in Chapter 18.41) . (See the Union City Parking menu for a quick reference.)
• Lot coverage and site-area minima/maxima are district‑by‑district; some districts expressly state “amount of site covered by structures shall not be restricted” while others impose explicit lot coverage limits (e.g., single‑family lot coverage: 60% one‑story / 50% two‑story in some districts) — consult the district chapter for the numeric table (examples at § 18.32 and § 18.88) .
• Design and pedestrian standards (plazas, minimum walkway widths, sign plans and context‑sensitive frontages) are regulated in the district chapters and in Chapter 18.24 and station/area chapters; some corridors (Old Alvarado, Mission Boulevard) carry additional design guidelines cited in the district chapters (for instance Old Alvarado design guidelines are referenced in the commercial rules) .

For citywide numeric standards and waivers, check the district tables and the cross‑references in Chapter 18.24 and the applicable district chapter.

Specific plans & overlays (what changes the base rules)

• 511 Area Specific Plan: implemented through Chapter 18.100 (511 Area District); the chapter adopts land‑use categories by reference and requires that development follow Chapters 18.72 and 18.76 procedures among other specific standards (§ 18.100.010 – § 18.100.090) .
• Union Landing has its own commercial district (CUL, Chapter 18.39) and detailed development‑type tables that limit which uses are allowed where in Union Landing — see § 18.39.030 – § 18.39.050 for performance criteria and use tables .
• DIPSA (Decoto Industrial Park Study Area, Chapter 18.102) imposes buffers, special setbacks from Mission Boulevard and high‑quality material/detail requirements for new residential neighborhoods in that study area .
• Overlays that modify base rules include the Hillside Combining (-H, Chapter 18.96), Floodplain Combining (Chapter 18.98), Landmark & Historic Preservation Overlay (Chapter 18.106) and the Housing Element Overlay (HE, Chapter 18.116) which establishes maximum site‑area per dwelling unit to meet the Housing Element’s density commitments (see § 18.116.010 – § 18.116.030) . See the Overlay Districts menu for clickable navigation to those rules.

Building permits & review — the practical path

• Who decides: the code vests administration in the Economic & Community Development Director, the Zoning Administrator and the Planning Commission depending on the permit type; the Director issues zoning permits and acts as or appoints the Zoning Administrator (§ 18.52.010 – § 18.52.090) .
• Typical permit paths:
  • Ministerial / Zoning Permit: for uses and projects that comply with objective standards — apply to the Director / Zoning Administrator (see Chapter 18.52) .
  • Administrative Site Development Review (Chapter 18.72): a streamlined process for certain projects; the Director/Zoning Administrator may approve administratively unless the project is controversial or triggers criteria requiring Planning Commission review (see Chapter 18.72 and § 18.72.070 for referral triggers) .
  • Site Development Review (Chapter 18.76): full Planning Commission review for projects that require a public hearing; applies citywide to projects identified in the chapter (§ 18.76.010 – § 18.76.110) .
  • Use Permits / Administrative Use Permits: conditional/allowed‑with‑conditions uses are handled under Chapters 18.54 (Administrative Use Permit) and 18.56 (Use Permits); some uses require Zoning Administrator, Planning Commission or City Council approval depending on the table in the district chapter .
  • Variances and appeals: handled under Chapter 18.60 (Variance Permits) and appeals processes are described in Chapter 18.52 (notice and hearing rules are cross‑referenced there) .
• Plan submittal & building code: every building‑permit application must be accompanied by the plats, plans and certifications required by the zoning director; the Chief Building Official inspects for building‑code compliance and the zoning title requires a zoning permit showing zoning compliance accompany building permit submittals (see the Director powers and permit submittal requirements) . For construction standards, the zoning code references standard building/occupancy rules (Uniform/State building code references appear in multiple district use tables) and the city enforces building-code requirements as part of permit review . (See the California Building Standards Code link for state code reference.)

State housing law in Union City — how ADUs, SB 9, density bonus and other state rules interact

• ADUs / JADUs:
  • Union City implements ADU rules in Chapter 18.34 (Accessory Dwelling Units); the chapter adopts state-oriented ADU standards (size, setbacks, parking exemptions, no passageway requirement, separate utility rules, short‑term rental prohibition under 30 days, impact‑fee triggers) and specifies setbacks: side & rear minimums of 4 ft for certain ADUs and that ADUs are not subject to the city’s minimum parking requirements in some circumstances (see the ADU chapter for the full list and § references) . (See the ADU menu for a focused summary.)
• SB 9 (two‑unit law and urban lot splits):
  • Union City created a local SB 9 chapter — Chapter 18.31 (SB 9 Subdivisions and Development Projects, § 18.31.010 – § 18.31.110) — that implements objective local standards: maximum of two SB 9 units per parcel, rules for urban lot split (no more than two resulting parcels, min parcel sizes and frontage rules), setbacks for SB 9 units (interior side & rear 4 ft, corner street‑side 10 ft), height caps for the portion between the 4‑ft offset (16 ft), parking requirement of one covered off‑street space per SB 9 unit (with transit/carpool exceptions), separate utility requirements and ministerial review/ministerial parcel map approval for urban lot splits when the chapter’s criteria are met (§ 18.31.010 et seq.) .
• Density bonus and affordable housing:
  • The city has an Affordable Housing chapter and a Housing Element (HE) Overlay, Chapter 18.116, which implements minimum‑density expectations for sites rezoned under the Housing Element and cross‑references Government Code density rules (e.g., minimum 20 du/acre where appropriate). Inclusionary and affordable‑housing requirements and in‑lieu fee mechanisms are in the affordable housing chapters (see Chapter 18.33 and Chapter 18.116) .
• Rent control / tenant protections: Union City’s Title 18 is focused on land use; the zoning code itself does not create citywide rent control language in Title 18. For rental limitations tied to housing programs (affordable units, HE overlay and inclusionary requirements) see Chapter 18.33 and related Affordable Housing sections; for citywide rent control you must confirm via the broader municipal code and Council ordinances (not in the zoning chapters retrieved here) .
• Practical note: the SB 9 chapter expressly provides that planned‑unit development or specific‑plan standards may apply only to the extent they do not conflict with State law and that SB 9 applications are eligible for ministerial approval when they meet the chapter’s objective criteria (Chapter 18.31, § 18.31.010 et seq.) .

Where to read the specific rules (quick navigation tips)

• For district use tables: open Chapter 18.32 (Residential) (§ 18.32.010 – § 18.32.190), Chapter 18.36 (Commercial, § 18.36.010 – § 18.36.210) and Chapter 18.40 (Industrial) to find permitted vs. conditional uses and cross‑references to parking and signs .
• For parking numbers: see § 18.32.160 (residential parking) and § 18.36.150 (commercial parking) and the Station/BART tables for transit‑adjacent waivers or reduced requirements . (See the Union City Parking page for a simplified reference.)
• For discretionary vs. ministerial process: read Chapter 18.52 (Administration) for who decides and Chapters 18.54/18.56/18.72/18.76 for the procedure and findings required at each level .
• For ADUs and SB 9 specifics: read Chapter 18.34 (ADUs) and Chapter 18.31 (SB 9) for the objective standards and ministerial rules (§ 18.31.010 – § 18.31.110) .

Source References

• Union City Zoning Code — Title 18 (General Provisions and chapter list) (§ 18.04.010 – § 18.04.210)
• Chapter 18.32 — Residential Districts (§ 18.32.010 – § 18.32.190)
• Chapter 18.36 — Commercial Districts (§ 18.36.010 – § 18.36.210)
• Chapter 18.24 — General Development / Bulk Regulations (§ 18.24.010 – § 18.24.050)
• Chapter 18.31 — SB 9 Subdivisions and Development Projects (§ 18.31.010 – § 18.31.110)
• Chapter 18.34 — Accessory Dwelling Units (ADUs) (ADU provisions summarized)
• Chapter 18.41 / Table 18.41.060 — Station / Mixed‑Use employment development standards (FAR, frontage, height)
• Chapter 18.76 — Site Development Review (procedures & applicability) (§ 18.76.010 – § 18.76.110)
• Chapter 18.52 — Administration (decision makers, permits, appeals) (§ 18.52.010 – § 18.52.090)

(If you want direct topic pages, use the internal site menus for Union City: Union City Zoning, Union City Development Standards, Union City Parking, Union City Design Review, Union City Overlay Districts, Union City ADUs, and the California Building Standards Code pages.)