Bolthole Index

Alameda County, California

Zoning, building permits and septic rules in Union City, California

Union City, California adopts its own zoning under Title 18 of the city code1, and the city's Building Division takes building permit applications at its counter2. Inside Union City, zoning questions go to the city Planning Division3, not the Alameda County planning counter. Septic systems are regulated by Alameda County's Department of Environmental Health, which administers septic rules in the county's cities as well as in unincorporated land4.

At a glance

Zoning
City-run: Title 18 of the Union City code applies inside city limits1
Building permits
Issued by the Union City Building Division, not Alameda County2
Septic
Alameda County Department of Environmental Health administers septic rules in the county's cities4
Smallest single-family lot (RS districts)
Minimum site area runs from 10,000 sq ft in RS 10000 down to 4,500 sq ft in RS 450056
Front yard (RS districts)
20 feet; 25 feet in RS 10000 and RS 800078
Height (RS districts)
30 feet for a principal structure9
Manufactured homes
Allowed as the sole residence on a single-family lot in RS and R districts, if built after June 15, 197610
Accessory dwelling unit
One ADU per single-family site, with more where chapter 18.31, 18.32 or state law allows11

Who to call

Building permits

City of Union City Building Division

Building permits, plan submittals, resubmittals and inspection requests inside Union City

510.675.5313

[email protected]

34009 Alvarado-Niles Road, Union City, CA 94587

Planning & zoning

City of Union City Planning Division

Zoning inquiries and land-use applications inside Union City

510.675.5379

[email protected]

34009 Alvarado-Niles Road, Union City, CA 94587

Septic permits

Alameda County Department of Environmental Health

Onsite wastewater (septic) permits, inspections and five-year reporting in Alameda County

(510) 618-3452

1000 San Leandro Blvd., Suite 300, San Leandro, CA 94577

Online permits →

Contact details are copied from each office’s official page and were checked against it on October 23, 2026.

Off-grid gear

Going off-grid in Union City means bringing your own water and power. The kit we’d start with:

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Does Union City, CA have zoning, and what does it mean for lot size and setbacks?

Yes. Union City sets zoning through its own Title 18 of the city code, and that zoning applies inside city limits, not in unincorporated Alameda County1. The residential districts chapter defines the RS (single-family) and RM (multifamily) districts12.

In the single-family RS districts, minimum site area is 10,000 square feet in RS 100005 and 4,500 square feet in RS 45006. A lot of record that already existed may still be developed under a separate provision of the chapter13.

The minimum front yard in the RS districts is 20 feet7, except in RS 10000 and RS 8000, where it is 25 feet8. Side yards for residential uses are 10% of site width, with no more than 10 feet required and at least 5 feet permitted, subject to listed exceptions14. A principal structure in an RS district may not exceed 30 feet9, and structures may cover at most 50% of the site15.

Can you live in an RV or tiny home in Union City?

We could not confirm Union City's rules for living in an RV, camping on private land, or placing a tiny home. Those rules would sit in the zoning and building codes, and the Planning Division is the office to ask before you buy3.

What the city's residential chapter does confirm: a manufactured home built after June 15, 1976 is allowed as the sole principal residence on a single-family lot in RS and R districts, on a continuous concrete foundation with permanent utility connections10. One accessory dwelling unit is allowed per single-family site, with more where chapter 18.31, 18.32 or state law permits11.

Do you need a building permit in Union City, and who issues it?

Inside Union City, building permit applications go to the city's own Building Division, which accepts submittals, resubmittals and revisions at its counter2. Alameda County's Building Inspection Department serves unincorporated areas, so the county permit portal is the wrong office for a Union City address16.

We could not confirm from the city code which work is exempt from a building permit, so ask the Building Division before starting. California's owner-builder exemption covers contractor licensing only and does not remove permits or inspections17. New buildings follow the 2025 California Building Standards Code when the permit application date is on or after January 1, 202618.

How do septic permits work inside Union City?

Alameda County's Department of Environmental Health regulates septic systems throughout unincorporated areas and also administers the rules in the county's various cities4. Septic is therefore a county matter even though zoning and building permits belong to the city.

We could not confirm whether a given Union City address is required to connect to public sewer or whether septic is allowed there at all. The county's rule is that a new or replacement system must connect to an available public sewer within 200 feet of the building19. Ask the Department of Environmental Health and the city Building Division before assuming a septic system is an option20.

Building a home in Union City: the steps, in order

  1. Call the Planning Division to confirm the parcel's zoning district and which setbacks, height and coverage limits apply3.
  2. Ask the Department of Environmental Health whether the address must use public sewer or can use a septic system20.
  3. Submit plans to the Building Division counter and ask what work needs a building permit2.
  4. If a septic system is allowed, the county's standard process requires a construction permit from the Department of Environmental Health after final building plan approval and before installation21.
  5. Request inspections through the Building Division, which limits the number of inspections per business day, so book early2.

What stays with Alameda County, and what to check before you buy

Septic regulation stays with Alameda County's Department of Environmental Health4. Land outside Union City limits falls under the county; see the Alameda County page for unincorporated rules.

Wells: the county's well permit program lists Union City under the Alameda County Water District rather than the county's own well program22. Confirm the well rules with that district before drilling.

Prices and tax context are county-level: the typical Alameda County home value is about $1,076,79823 and the effective property tax rate is 0.8%24.

Watch-outs

  • We could not confirm the city's building permit exemptions, building code adoption, inspection steps or fees; call the Building Division before you plan work2.
  • Alameda County's own lot, setback and height standards apply only in unincorporated areas, not inside Union City25.
  • We read only the residential districts chapter of Title 18; commercial and other districts may carry different standards12.

Sources

  1. Table of contents - Union City, CA eCode360 (Union City), quoted and re-checked
  2. City of Union City Building Division (unioncityca.gov)
  3. City of Union City Planning Division (unioncityca.gov)
  4. Local Agency Management Program for Onsite Wastewater Treatment Systems, Alameda County, quoted and re-checked
  5. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  6. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  7. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  8. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  9. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  10. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  11. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  12. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  13. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  14. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  15. Chapter 18.32: Residential Districts - Union City, CA (Union City), quoted and re-checked
  16. Alameda County Permit Portal — Building Permits, quoted and re-checked
  17. Owner-Builder Overview, quoted and re-checked
  18. Approved Building Standards (California statewide rule), quoted and re-checked
  19. Local Agency Management Program for Onsite Wastewater Treatment Systems, Alameda County, quoted and re-checked
  20. Alameda County Department of Environmental Health (deh.acgov.org)
  21. Standard OWTS Construction Permit Issuance Process, quoted and re-checked
  22. Wells Drilling Permits, quoted and re-checked
  23. Typical home value (Zillow): Bolthole Index county data
  24. Effective property tax rate: Bolthole Index county data
  25. Planning - Community Development Agency - Alameda County, quoted and re-checked

Written October 23, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

Answers from the rulebook for Union City

Union City’s own rules

  • Local zoningPresent (with conditions)

    Land inside Union City city limits, administered by the city under its own Title 18 zoning code

    • Zoning is set by the city's own Title 18; the city's zoning applies inside its limits, not in unincorporated Alameda County.
    “title 18 zoning (§ 18.04.010 – § 18.118.060)”
  • Zoning districtsPartial

    Residential zoning districts (RS and RM) inside Union City city limits

    • Only the residential districts chapter was read; commercial and other district chapters were not checked.
    “the purpose of this chapter is to define allowable uses and provide property development standards for the rs and rm zoning districts”
  • Minimum lot sizeDistrict specific (with conditions)

    RS 10000 single-family residential district inside Union City city limits

    • Applies to a lot recorded after the effective date of the chapter; a lot of record existing on that date may be developed under § 18.32.050(c).

    minimum site area (RS 10000): >= 10000 square feet

    “the minimum site area shall be as prescribed in the following table: district site area rs 10000 10,000 square feet”
    4 more reviewed findings on this topic
    • District specific (with conditions) — RS 8000 single-family residential district inside Union City city limits
      “the minimum site area shall be as prescribed in the following table: district site area rs 10000 10,000 square feet rs 8000 8,000 square feet rs 7000 7,000 square feet rs 6000 6,000 square feet rs 4500 4,500 square feet”
    • District specific (with conditions) — RS 7000 single-family residential district inside Union City city limits
      “the minimum site area shall be as prescribed in the following table: district site area rs 10000 10,000 square feet rs 8000 8,000 square feet rs 7000 7,000 square feet rs 6000 6,000 square feet rs 4500 4,500 square feet”
    • District specific (with conditions) — RS 6000 single-family residential district inside Union City city limits
      “the minimum site area shall be as prescribed in the following table: district site area rs 10000 10,000 square feet rs 8000 8,000 square feet rs 7000 7,000 square feet rs 6000 6,000 square feet rs 4500 4,500 square feet”
    • District specific (with conditions) — RS 4500 single-family residential district inside Union City city limits
      “the minimum site area shall be as prescribed in the following table: district site area rs 10000 10,000 square feet rs 8000 8,000 square feet rs 7000 7,000 square feet rs 6000 6,000 square feet rs 4500 4,500 square feet”
  • SetbacksSpecified

    Side yards for residential uses in residential districts inside Union City city limits

    • Side yard is 10% of site width, with a maximum required of 10 feet and a minimum permitted of 5 feet, subject to listed exceptions (interior access side yards of at least 12 feet, corner-lot street side yards) that were not read in full.
    • Accessory dwelling unit side-yard standards in r and rs districts are listed as an exception in the same subsection.

    side yard as share of site width: 10 percent (maximum 10 feet required; minimum 5 feet permitted subject to exceptions)

    “the minimum side yard for residential uses shall be 10% of the width of the site; provided, that a side yard of not more than 10 feet shall be required and a side yard of not less than five feet shall be permitted subject to the following exceptions:”
    2 more reviewed findings on this topic
    • District specific (with conditions) — Front yard in RS districts other than RS 10000 and RS 8000 (RS 7000, RS 6000, RS 4500) inside Union City city limits
      “in the rs districts the minimum front yard shall be 20 feet.”
    • District specific (with conditions) — Front yard in RS 10000 and RS 8000 single-family residential districts inside Union City city limits
      “except that in the rs 10000 and rs 8000 districts the minimum front yard shall be 25 feet.”
  • Lot coverageDistrict specific (with conditions)

    RS 10000, RS 8000, RS 7000, RS 6000 and RS 4500 single-family residential districts inside Union City city limits

    • Maximum site area covered by all structures, as stated in the table; RM districts (70% to 80%) are not covered by this claim.

    maximum site coverage by all structures: <= 50 percent of site area

    “the maximum site area covered by all structures located on the site shall be as prescribed in the following table: district coverage rs 10000 50% rs 8000 50% rs 7000 50% rs 6000 50% rs 4500 50%”
  • Building heightDistrict specific (with conditions)

    Principal structures in RS single-family residential districts inside Union City city limits

    • Spires, cupolas, chimneys, elevator penthouses, flagpoles and necessary mechanical appurtenances may reach 40 feet; amateur radio antennas are governed by § 18.32.190.
    • RM 2500 and RM 3500 allow 45 feet; RM 1500 allows 75 feet (multifamily, not claimed here).

    maximum height of principal structure: <= 30 feet (appurtenances up to 40 feet)

    “in the rs district, no principal structure shall exceed 30 feet in height. spires, cupolas, chimneys, elevator penthouses, flagpoles and necessary mechanical appurtenances may be allowed to a maximum height limit of 40 feet.”
  • Manufactured homesAllowed (with conditions)

    Manufactured home as sole principal residence on a single-family lot in RS and R districts inside Union City city limits

    • Home must have been constructed after June 15, 1976.
    • Each unit must have a continuous concrete foundation and permanent utility connections, and conform to all applicable building, plumbing, electrical and fire codes.
    • All provisions of the title applicable to one-family residential structures apply unless preempted by state law.
    “in rs and r districts, manufactured homes placed as a sole principal residence on a single-family lot and constructed after june 15, 1976, subject to the following requirements:”
  • Accessory dwellingsAllowed (with conditions)

    Accessory dwelling unit on a single-family site in single-family residential districts (including R, RS, RS(S) and 511 districts) inside Union City city limits

    • No more than one principal dwelling unit and one accessory dwelling unit per site, unless otherwise permitted under chapter 18.31, 18.32, or state law.
    • Detailed ADU size, parking and setback standards were not read; see followups.

    accessory dwelling units per site: 1 unit (additional units as permitted under chapter 18.31, 18.32 or state law)

    “in the single-family residential districts including the r, rs, rs(s) and 511 districts, no more than one principal dwelling unit and one accessory dwelling unit shall be located on each site unless otherwise permitted under chapter 18.31, 18.32, or state law.”
  • Subdividing landRegulated (with conditions)

    Land divisions inside Union City city limits

    • Title 17 Subdivisions is codified in the city code; the substantive map, lot-split and parcel-map rules were not read.
    “title 17 subdivisions (§ 17.04.010 &ndash; § 17.88.080)”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Union City or Alameda County directly.

  • Building permit — Building permit for new home construction inside Union City city limits
  • Owner-builder exemption — Owner-builder permit exemption inside Union City city limits
  • Building code adopted — Adoption of California building codes inside Union City city limits
  • Inspections — Building inspections for new home construction inside Union City city limits
  • Certificate of occupancy — Certificate of occupancy for a new home inside Union City city limits
16 more unanswered
  • Minimum dwelling size
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Mandatory utility hookup
  • Agricultural exemption
  • Driveway access
  • Building in a floodplain
  • Short-term rentals
  • Permit fees
  • Permit process

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that Union City publishes no rule on the point, not that none exists. Alameda County’s page lists the county offices to call.

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