San Marcos, CA Building Setbacks & Zoning: Setback Rules (2026)

32 of the San Marcos Municipal Code, the city's Grading Regulations, sets the setback standards for any cut or fill slope created under a grading permit. 110(a) makes clear the listed setbacks are minimums only: the Administrative Authority, or the written recommendation of the project's Engineer of Record, Geotechnical Engineer, or Engineering Geologist, can require a larger setback for safety and stability, to prevent erosion or deposition damage to neighboring parcels, or to preserve access for slope maintenance and drainage. A retaining wall can be used to shrink the required setback, but only with Administrative Authority approval.

110(b) ties the actual distances to Figure No. 2: the top of a cut slope and toe of a fill slope must be set back from buildings, the property line, the public right-of-way, and easement boundaries. Figure No. 2 scales the setback to slope height (H): under 5 feet of slope, the setback is 0 feet from the toe and 1 foot from the top; between 5 and 30 feet, it is H/2 from the toe and H/5 from the top; over 30 feet, it is a flat 15 feet from the toe and 6 feet from the top, with additional width required where an interceptor drain is needed.

Frontage right-of-way or easement areas must be graded at a 1 percent to 2 percent slope unless the Administrative Authority allows otherwise. 110(c) separately requires foundation setbacks between graded slopes and structures per Figure No. 3. Subsection (d) requires subdivisions to place lot lines at the top of slope absent extreme topography, and subsection (e) requires a signed letter of permission from any adjacent property owner before the City issues a grading permit for work that encroaches onto or disturbs the neighboring parcel.