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Union City · Building on your lot

Building on a hillside in Union City

Union City's own rules on building on a hillside, with the code text for every value.

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Each rule below links to the section of the Union City Municipal Code it was read from, with the code text one click away (checked October 2026). General information, not legal advice.

What Union City's code says

Union City code What Union City's code adds
Grading and retaining walls
  • No artificial slope steeper than nearby natural slopes or 3:1, whichever is greater.
    Applies: Hillside area grading guidelines.
    § 18.96.065 · code text
    No artificial slope shall exceed the naturally occurring slopes in its immediate vicinity or a slope of 3:1, whichever is greater.
  • Grading should generally stay within the building footprint, under access roads and driveways, or where needed for landslides.
    Applies: Hillside area grading guidelines.
    § 18.96.065 · code text
    Site grading should generally be limited to areas within the building footprint, under access roads and driveways, and where necessary due to unusual site conditions such as landslides.
When hillside rules apply
  • Average slopes over 10%.
    Applies: Only part of the base-zone unit count is credited there: 0.50 for 10.1–15%, down to 0.00 over 40%.
    § 18.96.040 · code text
    For portions of the site with an existing average slope exceeding 10%, credit may be claimed based on a proportion of the maximum number of units that would be allowed under the base zoning district in accord with the following table:
  • Slopes above 10%.
    Applies: Grading must be minimized and contoured.
    § 18.96.065 · code text
    Grading shall be minimized in all areas with slopes above 10% by properly contouring areas where grading occurs.

Who this affects

HomeownersContractorsDesigners

Frequently asked questions

What extra rules apply to a hillside lot in Union City?

Union City's code: Average slopes over 10%. (Only part of the base-zone unit count is credited there: 0.50 for 10.1–15%, down to 0.00 over 40%.) (§ 18.96.040); No artificial slope steeper than nearby natural slopes or 3:1, whichever is greater. (Hillside area grading guidelines.) (§ 18.96.065).

General information, not legal advice.

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