Before You Build in Union City, CA: Permit & Rule Checklist (2026)

Union City limits fences to 3 feet within front and exterior/street side setbacks and 6 feet in rear and interior side yards. Up to 8 feet is allowed where a yard abuts qualifying uses such as a flood control channel, railroad, school, or major arterial.

A fence on top of a retaining wall is allowed only when the combined height of wall plus fence does not exceed the applicable fence height limit in UCMC 18.32.040(A). Exposed exterior retaining wall faces must be architecturally treated.

No permit is required for walls, fences, or hedges under 7 feet measured from grade. A building permit is required for fences over 7 feet, and for any gate on a multi-family lot that crosses a driveway, fire lane, or sidewalk access.

Fences and walls must aesthetically complement the yard and be compatible with neighboring yards, fences, and structures. Where an 8-foot fence adjoins a lower fence, it must step or slope down to match the adjoining height or 6 feet, whichever is greater.

Acceptable fence materials are natural materials such as wood, masonry, and earth. Fences and walls must aesthetically complement the yard and be compatible with neighboring yards, fences, and structures.

Union City enforces California's Swimming Pool Safety Act for pool barriers through its building permits. Under Health and Safety Code 115922, new or remodeled residential pools need at least two of seven drowning-prevention features, and any enclosure must meet Section 115923's 60-inch minimum height.

Building a swimming pool or spa in Union City requires permits from the Building Division. The city's Building Permit Requirements handout requires building, plumbing, mechanical, and electrical permits for most construction. Only prefabricated pools less than 24 inches deep are exempt.

Pool safety in Union City is governed by California's Swimming Pool Safety Act, applied through the city's building permits. New and remodeled residential pools and spas must include at least two of seven state-approved drowning-prevention safety features under Health and Safety Code Section 115922.

Above-ground pools in Union City generally require building and related permits from the Building Division. The city's Building Permit Requirements handout exempts only prefabricated swimming pools that are less than 24 inches deep, so deeper above-ground pools need permits and must meet the state Pool Safety Act barrier standards.

Hot tubs and spas in Union City are treated as construction requiring permits. The city's Building Permit Requirements handout lists no spa or hot tub exemption, so a building, plumbing, mechanical, and electrical permit is needed for most installations, and spas fall under California's pool safety standards.

Union City regulates accessory dwelling units under UCMC Chapter 18.34 (Ordinance 900-22), implementing California state ADU law. ADUs are approved ministerially without a hearing, no owner-occupancy is required for ADUs, and up to two ADUs are allowed on a single-family lot.

Union City allows converting an existing garage into an accessory dwelling unit under UCMC Chapter 18.34. The conversion is reviewed ministerially with a building permit, and the city cannot require replacement of the off-street parking spaces lost to the conversion.

Union City treats detached carports as accessory structures under UCMC Chapter 18.32. Carports must sit on the rear half of the lot, meet four-foot side and rear setbacks, and stay within the 12-foot height limit, with permits required above small sizes.

Union City regulates detached accessory structures such as storage sheds under UCMC Chapter 18.32. Sheds under 120 square feet with no utilities need no permit, while larger sheds require building or planning permits, and all must meet setback and height limits.

Union City has no standalone tiny-house ordinance. A tiny home on a permanent foundation is reviewed as an accessory dwelling unit under UCMC Chapter 18.34, while a tiny home on wheels is treated as a recreational vehicle and cannot be a permanent residence.

Open burning of yard waste, debris, or trash is effectively prohibited in Union City. Bay Area Air Quality Management District Regulation 5 bans most open burning region-wide, and the California Fire Code requires a permit for any allowed open burning. Residents should use green-waste and refuse collection instead.

Union City has no special fire-pit ordinance beyond the California Fire Code, adopted as its 2025 edition in Municipal Code Chapter 15.20. Recreational fires must stay at least 25 feet from structures, portable outdoor fireplaces 15 feet, and the fire must be attended until fully out.

Union City's water purveyor is the Alameda County Water District (ACWD), serving the Tri-City area. ACWD enforces permanent water-waste prohibitions year-round and adds day-limited irrigation only when its Board declares a shortage emergency.

Union City protects significant trees on private property. Under UCMC 12.16.170 it is unlawful to trim or remove a protected tree without a Public Works permit, and trees in any street, park, or public place also require a permit.

Union City limits removal of significant trees. UCMC 12.16.170 makes it unlawful to remove a protected private tree without a Public Works permit, which may require replacement trees, and unauthorized removal triggers the tree's appraised value.