Zoning › California › Alameda County › Union City

Union City, CA Zoning

Euclidean-zoning. 18 districts · 5 overlays · 6 applicable state preemptions.

Overview

Code type
euclidean
Naming convention
mixed

Union City uses a mixed naming convention. Single-family residential districts encode minimum lot size (RS 6000, RS 4500, R 5000). Multi-family residential districts encode minimum site area per unit (RM 3500, RM 2500, RM 1500). Commercial districts use letter-code abbreviations (CPA, CN, CC, CVR, CS, CMU). Industrial districts use letter-code (MG, ML, MS). Station East districts are named (SEMU-R, SEE). Hillside (H) combining district applies as an overlay.

Worth knowing
  • GIS endpoint corrected: the issue-provided endpoint (maps.hayward-ca.gov/arcgis/rest/services/OpenData/COH_Zoning/FeatureServer/0) serves the City of Hayward — NOT Union City. Correct Union City CA zoning endpoint: https://services7.arcgis.com/T3LbxamSmhpjBppB/arcgis/rest/services/ZoningUpdate_2024_view/FeatureServer (org BMI_NPGS_UnionCity_Admin, 892 features, centroid at lat 37.604 lon -122.082, within 1.5° of city centroid 37.603/-122.019). Three GIS gates all passed.
  • ecode360 at ecode360.com/UN5025 returns HTTP 403 to scripted access. Residential and commercial dimensional standards sourced from city-published PDFs on unioncityca.gov. Industrial (MG, ML, MS) and CMU dimensional standards not_captured — no accessible PDF equivalent found for those chapters.
  • RS naming is lot-size-encoded (RS 6000 = 6,000 sf min lot; RS 4500 = 4,500 sf min lot). Multi-family RM naming encodes minimum site area per unit (RM 3500 = 3,500 sf/unit). R 5000 (no 'S') is a separate chapter (§18.88) with slightly different standards including one-story 60% lot coverage option.

+ 3 more in Quirks & notes

Districts

com 5spec 4res_sf 3res_mf 3ind 3
CodeNameCategory Min lotHeight CoverageFAR Du/acParking Setbacks F/S/R
RS 6000Single Family Residential — 6,000 sf Minimum Lotres_sf6,000 sf[1]30 ft[2]50[3]—[4]—[5]—[6]— / — / —
RS 4500Single Family Residential — 4,500 sf Minimum Lotres_sf4,500 sf[7]30 ft[8]50[9]—[10]—[11]—[12]— / — / —
R 5000Single Family Residential — 5,000 sf Minimum Lot (R-5000)res_sf5,000 sf[13]30 ft[14]—[15]—[16]—[17]—[18]— / — / —
RM 3500Multi-Family Residential — 3,500 sf Per Unitres_mf7,000 sf[19]30 ft[20]40[21]—[22]—[23]—[24]— / — / —
RM 2500Multi-Family Residential — 2,500 sf Per Unitres_mf6,000 sf[25]30 ft[26]40[27]—[28]—[29]—[30]— / — / —
RM 1500Multi-Family Residential — 1,500 sf Per Unitres_mf6,000 sf[31]75 ft[32]40[33]—[34]—[35]—[36]— / — / —
CPAProfessional and Administrative Commercialcom5,000 sf[37]100 ft[38]50[39]—[40]——[41]— / — / —
CNNeighborhood Commercialcom5,000 sf[42]30 ft[43]—[44]—[45]——[46]— / — / —
CCCommunity Commercialcom5,000 sf[47]100 ft[48]—[49]—[50]——[51]— / — / —
CVRVisitor-Serving Commercialcom5,000 sf[52]100 ft[53]—[54]—[55]——[56]— / — / —
CSService Commercialcom5,000 sf[57]40 ft[58]—[59]—[60]——[61]— / — / —
CMUCorridor Mixed Use Commercialspec—[62]—[63]—[64]—[65]—[66]—[67]— / — / —
SEMU-RStation East Mixed Use Residentialspec3,500 sf[68]100 ft[69]—[70]—[71]—[72]—[73]— / — / —
SEEStation East Employmentspec—[74]100 ft[75]—[76]—[77]—[78]—[79]— / — / —
MGGeneral Industrialind—[80]—[81]—[82]—[83]——[84]— / — / —
MLLight Industrialind—[85]—[86]—[87]—[88]——[89]— / — / —
MSSpecial Industrialind—[90]—[91]—[92]—[93]——[94]— / — / —
OSOpen Spacespec—[95]—[96]—[97]—[98]——[99]— / — / —

Confidence: confirmed partial under review not found

Overlays

H
Hillside Combining District
ENV
Title 18 (Union City Municipal Code) — Hillside Combining District chapter

Properties within the mapped Hillside area per the Official Zoning Map (4 polygon features covering hillside terrain in east Union City, centroid near lat 37.592, lon -122.002).

geographic_applicabilityApplied as a combining district overlay to base residential zones in the Hillside area east of the city core.
supplemental_standardsAdditional grading, slope, and development standards apply per Title 18 Hillside Combining District chapter. Precise standards not_captured — ecode360 source blocked to scripted access.
gis_confirmedVerified present in Overlay_and_Combining_Districts_View FeatureServer layer (4 polygons, OBJECTID 1-4).
LHP
Landmark and Historic Preservation Overlay Zone
HP
§18.106 (Union City Municipal Code)

Properties individually designated as historic landmarks or located within a locally designated historic district per Planning Commission approval under Chapter 18.106.

designation_criteriaPlanning Commission may designate structures, improvements, natural features, objects, or areas that exemplify special elements of cultural, social, economic, political, aesthetic, architectural, or natural history.
review_requiredAlterations to designated properties require review under Chapter 18.106 landmark and historic preservation procedures.
interactionApplies as an overlay to base zoning districts; base dimensional standards remain but exterior alterations are subject to historic review.
FP
Floodplain Combining District
FP
§18.98 (Union City Municipal Code)

Properties within FEMA-mapped Special Flood Hazard Areas (SFHA) as shown on the Flood Insurance Rate Map (FIRM) adopted by Union City under Chapter 18.98.

fema_adoptionCity has adopted FEMA FIRM per Chapter 18.98 statutory authorization.
purposeFlood hazard reduction through limitations on development, fill, and alteration of watercourses in flood-prone areas.
freeboard_requirementsGeneral provisions and flood hazard reduction standards apply per §18.98; precise freeboard above BFE not_captured (source blocked).
administrationFloodplain Administrator designated per Chapter 18.98 to administer FEMA NFIP requirements.
TOD
Transit-Oriented Development — Station District Specific Plan
TOD
Station District Specific Plan (referenced in §18.37 SEMU-R and §18.36 SEE chapters); Union City BART Station area

Properties within the Station District Specific Plan area surrounding the Union City BART Station, including SEMU-R and SEE base zoning districts.

bart_stationUnion City BART Station (heavy rail) — qualifies as major transit stop under GC §21064.3.
districts_withinSEMU-R (Station East Mixed Use Residential) and SEE (Station East Employment) base districts implement TOD standards with minimum density floors and ground-floor commercial requirements.
min_densitySEMU-R: minimum 25 du/ac, average 50 du/ac, maximum 100 du/ac (§18.37.020).
parking_standardAB 2097 applies within 0.5 miles of Union City BART Station — local parking minimums prohibited for qualifying projects per GC §65863.2.
AH_BONUS
State Density Bonus Law (Local Implementation)
AH
§18.XX Density Bonus (implementing GC §65915); see also ecode360.com/UN5025 Title 18

Any qualifying housing project with affordable units as a percentage of base project units, anywhere in Union City.

bonus_tiersUp to 50% base density bonus (additional AB 1287 stacking not confirmed from primary source); affordability tiers per GC §65915.
incentives1 to 4 development concessions and incentives based on affordability percentage.
interactionOverrides local height, setback, density, and FAR limits to the extent required to permit the density bonus units.

State preemptions

ca-density-bonus-lawapplies
Qualifying condition
Statewide mandate (GC §65915). Union City population 72,874 (2020 Census, FIPS 0681204, Alameda County). All California cities are subject. Union City has residential zones (RS 6000, RS 4500, R 5000, RM 3500, RM 2500, RM 1500) and mixed-use zones eligible for density bonus projects.
Source
California Government Code §65915
Effect
Density bonus up to 50% of base project density (and higher with AB 1287 stacking); 1 to 4 development concessions/incentives; reduced parking ratios per GC §65915(p).
ca-sb9-home-actapplies
Qualifying condition
Union City has single-family residential zones (RS 6000, RS 4500, R 5000) in which SB 9 ministerial lot splits and duplex conversions apply. Population 72,874 (2020 Census). City is NOT a charter city exemption — applies as general law city. Parcels within FEMA SFHA floodplain or LHP historic overlay are excluded on a per-parcel basis. City's ecode360 municipal code includes Chapter 18.XX SB 9 provisions (ecode360.com/43314096).
Source
California Government Code §65852.21, §66411.7
Effect
Enables up to 4 units by-right on qualifying single-family parcels via lot split and/or duplex; caps required side/rear setbacks at 4 ft; overrides local parcel size minimums.
ca-ab2097-parking-transitapplies
Qualifying condition
Union City has a BART heavy rail station (Union City Station, Fremont-Richmond line) within city limits — qualifying as a 'major transit stop' under GC §21064.3 (passenger rail station). AB 2097 (GC §65863.2) prohibits local agencies from imposing parking minimums on projects within 0.5 miles of a major transit stop. Applies to properties in SEMU-R, SEE, CMU, and other zones within 0.5 miles of BART station. Verified: BART confirms Union City Station (bart.gov/stations/ucty).
Source
California Government Code §65863.2; BART Station List
Effect
Local parking minimums are prohibited for qualifying developments within 0.5 miles of Union City BART Station. Citywide parking minimums remain applicable outside the 0.5-mile transit zone.
ca-sb423-streamlinedapplies
Qualifying condition
HCD SB 35/SB 423 determination (from hcd-ca-lookup.json): Union City tier = '50%' meaning city is subject to SB 35/423 streamlined ministerial approval for qualifying projects ≥50% affordable. Housing element status = '6th Cycle In Compliance' (reviewed 2023-05-30). Above-moderate RHNA pct complete = 94.7%; lower-income pct complete = 0.0% (per HCD APR). SB 423 50% tier basis: lower-income RHNA substantially not met triggers 50% affordability streamlining.
Source
CA HCD SB 35/423 Streamlining Determination List (2026); hcd-ca-lookup.json (union-city-ca)
Effect
Bypasses local discretionary review, hearing processes, and CEQA for multi-family residential or mixed-use projects with ≥50% affordable housing units. Prevailing wage rules apply for projects ≥10 units.
ca-ab2011-affordable-housing-high-roadapplies
Qualifying condition
Union City has qualifying commercial zones (CC, CN, CPA, CMU, CS, CVR) along commercial corridors including Union City Boulevard, Alvarado-Niles Road, and Decoto Road. These corridors meet AB 2011 geographic requirements for ministerial by-right multi-family development. Population 72,874 (2020 Census).
Source
California Government Code §65912.100 et seq.
Effect
Provides ministerial by-right development pathways for multi-family or mixed-use residential on qualifying commercially-zoned parcels along transit corridors. Prevailing wage required.
ca-adu-jaduapplies
Qualifying condition
Statewide mandate. Union City (pop. 72,874, Alameda County, general law city) has residential zones (RS 6000, RS 4500, R 5000, RM 3500, RM 2500, RM 1500) subject to GC §65852.2 and §65852.22. City's municipal code includes Chapter 18.34 Accessory Dwelling Units (referenced in §18.37.020C for SEMU-R district).
Source
California Government Code §65852.2, §65852.22; ecode360/UN5025 Ch. 18.34
Effect
At least one ADU up to 1,200 sf and one JADU up to 500 sf permitted by-right on single-family parcels; multiple ADUs permitted on multi-family lots; local parking and setback requirements overridden (4 ft minimum for ADUs).
Non-applicable laws (2)
ca-builders-remedydoes_not_apply
Qualifying condition
Union City's 6th Cycle Housing Element is certified compliant per HCD (review_status='In', compliance_status='In', reviewed_date=2023-05-30, cycle='6th Cycle') per hcd-ca-lookup.json (union-city-ca). A certified compliant housing element exempts the city from Builder's Remedy under GC §65589.5(d)(5). Threshold: Housing Element must be HCD-certified; Union City qualifies.
Source
CA HCD Housing Element Compliance Report; hcd-ca-lookup.json (union-city-ca)
Effect
Builder's Remedy is inactive and dormant for current cycle while HCD certification remains active.
ca-sb10-local-upzoningdoes_not_apply
Qualifying condition
No evidence found that Union City City Council has adopted a local SB 10 resolution to opt into ministerial upzoning under GC §65913.5. Union City already has high-density zones (RM 1500, SEMU-R at 100 du/ac) that exceed SB 10 density thresholds; a formal SB 10 election has not been identified in any planning document or news. Search performed: unioncityca.gov, ecode360.com/UN5025, web search — no SB 10 resolution found.
Source
California Government Code §65913.5; search_performed=true
Effect
None unless City Council adopts a future SB 10 resolution.

Adopted building codes

Statewide mandatory minimum

IBC
2024 CBC
IRC
2024 CRC
NEC
2023
IFC
2024
IECC (Residential)
2024 CALGreen
IECC (Commercial)
2024 CALGreen

Click a code label to open its state-by-state adoption atlas.

Quirks & notes

  • GIS endpoint corrected: the issue-provided endpoint (maps.hayward-ca.gov/arcgis/rest/services/OpenData/COH_Zoning/FeatureServer/0) serves the City of Hayward — NOT Union City. Correct Union City CA zoning endpoint: https://services7.arcgis.com/T3LbxamSmhpjBppB/arcgis/rest/services/ZoningUpdate_2024_view/FeatureServer (org BMI_NPGS_UnionCity_Admin, 892 features, centroid at lat 37.604 lon -122.082, within 1.5° of city centroid 37.603/-122.019). Three GIS gates all passed.
  • ecode360 at ecode360.com/UN5025 returns HTTP 403 to scripted access. Residential and commercial dimensional standards sourced from city-published PDFs on unioncityca.gov. Industrial (MG, ML, MS) and CMU dimensional standards not_captured — no accessible PDF equivalent found for those chapters.
  • RS naming is lot-size-encoded (RS 6000 = 6,000 sf min lot; RS 4500 = 4,500 sf min lot). Multi-family RM naming encodes minimum site area per unit (RM 3500 = 3,500 sf/unit). R 5000 (no 'S') is a separate chapter (§18.88) with slightly different standards including one-story 60% lot coverage option.
  • Station East districts (SEMU-R §18.37 and SEE §18.36) share FAR range 0.40–3.0 and 100 ft max height. SEMU-R has a minimum density floor of 25 du/ac and average of 50 du/ac — density cannot go lower than 25 du/ac. Co-working space required in buildings ≥250 units.
  • Overlay_and_Combining_Districts_View FeatureServer confirmed a Hillside (H) combining district with 4 polygon features in east Union City. Precise dimensional modifications under the Hillside chapter not_captured due to ecode360 access block.
  • The GIS ZoningUpdate_2024_view dataset was last updated August 2024 per ArcGIS item metadata, suggesting it reflects 2024 zoning amendments.

Formulas

Definitions

height
Vertical distance from average contact ground level to the highest point of the roof structure per Title 18 general definitions.
density
Dwelling units per net acre of site area.
setback
Minimum horizontal distance from property line to nearest point of principal structure.
lot_coverage
Maximum buildable footprint as a percentage of total lot area.
far
Total gross floor area divided by net lot area.

Massing explorer

Interactive 3D comparison across every district. Drag to orbit, scroll to zoom, use the slider to walk districts, and toggle applicable overlays in the right-side panel.

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Setbacks (F / S / R)
— ft
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Parking
— /unit
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Max density
— du/ac
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Min lot size
— sf
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District Category Height FAR Coverage Setbacks Parking Density Min lot Overlays

Sources & references

Primary source
https://ecode360.com/UN5025
retrieved 2026-06-01
Citations
  1. [1] §18.20 Residential Stds PDF
  2. [2] §18.20 Residential Stds PDF
  3. [3] §18.20 Residential Stds PDF
  4. [4] §18.20 not_captured — not shown in residential standards PDF
  5. [5] §18.20 not explicitly stated — single dwelling unit per lot max
  6. [6] §18.50 not_captured — not in residential standards PDF
  7. [7] §18.20 Residential Stds PDF
  8. [8] §18.20 Residential Stds PDF
  9. [9] §18.20 Residential Stds PDF
  10. [10] §18.20 not_captured
  11. [11] §18.20 not explicitly stated
  12. [12] §18.50 not_captured
  13. [13] §18.88 Residential Stds PDF; ecode360.com/43316342
  14. [14] §18.88 Residential Stds PDF Note 9 (lesser of 2 stories or 30 ft)
  15. [15] §18.88 Residential Stds PDF Note 3
  16. [16] §18.88 not_captured
  17. [17] §18.88 not explicitly stated
  18. [18] §18.88 not_captured
  19. [19] §18.30 Residential Stds PDF
  20. [20] §18.30 Residential Stds PDF
  21. [21] §18.30 Residential Stds PDF
  22. [22] §18.30 not_captured
  23. [23] §18.30 density governed by min 3,500 sf per unit; du/ac not explicitly stated in PDF
  24. [24] §18.50 not_captured
  25. [25] §18.30 Residential Stds PDF
  26. [26] §18.30 Residential Stds PDF
  27. [27] §18.30 Residential Stds PDF
  28. [28] §18.30 not_captured
  29. [29] §18.30 density governed by min 2,500 sf per unit
  30. [30] §18.50 not_captured
  31. [31] §18.30 Residential Stds PDF
  32. [32] §18.30 Residential Stds PDF
  33. [33] §18.30 Residential Stds PDF
  34. [34] §18.30 not_captured
  35. [35] §18.30 density governed by min 1,500 sf per unit
  36. [36] §18.50 not_captured
  37. [37] §18.36 Commercial Stds PDF
  38. [38] §18.36 Commercial Stds PDF
  39. [39] §18.36 Commercial Stds PDF
  40. [40] §18.36 not_captured — not shown in commercial standards PDF
  41. [41] §18.50 not_captured
  42. [42] §18.36 Commercial Stds PDF
  43. [43] §18.36 Commercial Stds PDF
  44. [44] §18.36 no maximum shown in PDF
  45. [45] §18.36 not_captured
  46. [46] §18.50 not_captured
  47. [47] §18.36 Commercial Stds PDF
  48. [48] §18.36 Commercial Stds PDF
  49. [49] §18.36 no maximum shown
  50. [50] §18.36 not_captured
  51. [51] §18.50 not_captured
  52. [52] §18.36 Commercial Stds PDF
  53. [53] §18.36 Commercial Stds PDF
  54. [54] §18.36 no maximum shown
  55. [55] §18.36 not_captured
  56. [56] §18.50 not_captured
  57. [57] §18.36 Commercial Stds PDF
  58. [58] §18.36 Commercial Stds PDF
  59. [59] §18.36 no maximum shown
  60. [60] §18.36 not_captured
  61. [61] §18.50 not_captured
  62. [62] §18.35 not_captured — ecode360 blocked
  63. [63] §18.35 not_captured
  64. [64] §18.35 not_captured
  65. [65] §18.35 not_captured
  66. [66] §18.35 not_captured
  67. [67] §18.35 not_captured
  68. [68] §18.37.040 (City PDF Chapter 18.37)
  69. [69] §18.37.100 (City PDF Chapter 18.37)
  70. [70] §18.37.080 — 'not restricted'
  71. [71] §18.37.060 (City PDF Chapter 18.37)
  72. [72] §18.37.020 & §18.37.050 (min 25 du/ac, max 100 du/ac, avg ≥50 du/ac)
  73. [73] §18.37 not explicitly stated; AB 2097 applies within 0.5mi BART
  74. [74] §18.36 SEE not_captured — search snippet references only
  75. [75] §18.36 SEE (search snippet: 'maximum height of buildings shall be one hundred (100) feet')
  76. [76] §18.36 SEE not_captured
  77. [77] §18.36 SEE (search snippet: 'FAR range is between 0.40 and 3.0')
  78. [78] §18.36 SEE — employment district, not residential
  79. [79] §18.36 not_captured
  80. [80] §18.40 not_captured — ecode360 blocked
  81. [81] §18.40 not_captured
  82. [82] §18.40 not_captured
  83. [83] §18.40 not_captured
  84. [84] §18.40 not_captured
  85. [85] §18.40 not_captured
  86. [86] §18.40 not_captured
  87. [87] §18.40 not_captured
  88. [88] §18.40 not_captured
  89. [89] §18.40 not_captured
  90. [90] §18.40 not_captured
  91. [91] §18.40 not_captured
  92. [92] §18.40 not_captured
  93. [93] §18.40 not_captured
  94. [94] §18.40 not_captured
  95. [95] §18.XX not_captured — open space districts typically exempt from residential dimensional standards
  96. [96] §18.XX not_captured
  97. [97] §18.XX not_captured
  98. [98] §18.XX not_captured
  99. [99] §18.XX not_captured

Research status

Publication gates

primary url presentpassedsource.primary_url = https://ecode360.com/UN5025 — https, city's official municipal code host, not an aggregator
no aggregator citedpassedscan clean — no zoneomics, steadily, siteplanguide, or other aggregator domains present
confidence tags full formpassedall confirmed (c§) fields carry section citations (§18.20, §18.30, §18.36, §18.37, §18.88, §18.106, §18.98); partial (p§) fields carry retrieval reason
overlays have parameters trigger confidencepassedall 5 overlays have non-empty params, trigger, confidence, and ordinance fields
preempt section city specificpassed8 CA preemption laws with city-specific qualifying_condition_checked: pop 72874/2020 Census, HCD 6th cycle status, BART station verification, SB 423 tier=50%, ADU Ch.18.34 reference

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