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Building on a hillside in San Marcos

San Marcos'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 San Marcos Municipal Code it was read from, with the code text one click away (checked October 2026). General information, not legal advice.

What San Marcos's code says

San Marcos code What San Marcos's code adds
Soils or geology report
  • A preliminary soils report from a certified engineer is required.
    Applies: Ridgeline development permit applications in the Ridgeline Overlay Zone; not needed for a single-family home or accessory building on a single lot.
    § 20.260.070 · code text
    A preliminary soils report submitted by a certified engineer.
Grading and retaining walls
  • Grading may cover no more than 25% of the lot area.
    Applies: Ridgeline Overlay Zone.
    § 20.260.050 · code text
    Grading shall be limited to no more than twenty-five percent (25%) of the lot area.
  • Cuts and fills deeper than 20 feet are discouraged.
    Applies: Ridgeline Overlay Zone.
    § 20.260.050 · code text
    Cuts and fill in excess of twenty (20) feet in depth are discouraged.
Height on hillside lots
  • Buildings may be at most 24 feet tall.
    Applies: Buildings approved by exception within the 100-foot primary or 50-foot secondary ridgeline setback.
    § 20.260.050 · code text
    Additionally, the structure shall not exceed a height of twenty-four (24) feet.
  • New buildings or room additions may be at most 28 feet tall.
    Applies: Ridgeline Overlay Zone.
    § 20.260.050 · code text
    Build new structures or room additions to not exceed a height of twenty-eight (28) feet.
  • Decks, trellises and similar features up to 28 feet tall are exempt.
    Applies: Existing homes outside the ridgeline setback; no added building or roof area.
    § 20.260.030 · code text
    Architectural elements, including decks, trellises, and other similar architectural enhancements that do not increase the building or roofing square footage and do not exceed a maximum building height of twenty-eight (28) feet.
  • Home expansions up to 28 feet tall are exempt.
    Applies: Existing homes outside the ridgeline setback; up to 1,000 square feet added footprint and 4,500 square feet total.
    § 20.260.030 · code text
    An expansion is proposed provided that expansion does not exceed 1,000 square feet of additional building footprint and that the total combined square footage does not exceed 4,500 square feet maximum or a building height of twenty-eight (28) feet.
  • Decks, trellises and similar features up to 24 feet tall are exempt.
    Applies: Existing main homes within the ridgeline setback; no added footprint.
    § 20.260.030 · code text
    Architectural elements, including decks, trellises, and other similar architectural enhancements, are proposed that do not increase the building footprint and do not exceed a building height of twenty-four (24) feet.
  • Home expansions up to 24 feet tall are exempt.
    Applies: Existing main homes within the ridgeline setback; up to 500 square feet added, total footprint up to 3,000 square feet.
    § 20.260.030 · code text
    An expansion is proposed provided that the expansion does not exceed five hundred (500) square feet of additional building footprint, create a new building footprint exceeding 3,000 square feet, or exceed a building height of twenty-four (24) feet.
  • New accessory buildings up to 24 feet tall are exempt.
    Applies: Footprint of 200 square feet or less.
    § 20.260.030 · code text
    New accessory structures that do not exceed two hundred (200) square feet in building footprint or a building height of twenty-four (24) feet.
  • Accessory building expansions up to 24 feet tall are exempt.
    Applies: Up to 200 square feet added, total footprint no more than 400 square feet.
    § 20.260.030 · code text
    Expansion of existing or approved accessory structures that do not exceed two hundred (200) square feet of additional building footprint or a building height of twenty-four (24) feet, or create a new building footprint exceeding four hundred (400) square feet.

Who this affects

HomeownersContractorsDesigners

Frequently asked questions

What extra rules apply to a hillside lot in San Marcos?

San Marcos's code: Grading may cover no more than 25% of the lot area. (Ridgeline Overlay Zone.) (§ 20.260.050); Cuts and fills deeper than 20 feet are discouraged. (Ridgeline Overlay Zone.) (§ 20.260.050).

General information, not legal advice.

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San Marcos Municipal Code — full text