San Marcos, CA Building Setbacks & Zoning: Lot Coverage Limits (2026)

Lot coverage - the maximum lot area that may be covered by buildings - is regulated in unincorporated San Diego County by the Coverage Regulations (Sections 4700-4799) and is assigned through a Coverage Designator in each property's zoning. Section 4705 (Coverage Designator Notation) provides two ways coverage may be expressed, with the most restrictive controlling: (1) an Arabic numeral stating, as a decimal fraction, the maximum portion of the lot or building site that may be covered by all buildings (for example, 0.40 = 40 percent), and (2) an Arabic numeral stating, as a whole number, the maximum building-covered area in square feet. A dash ('-') indicates that maximum coverage is not regulated, except as otherwise limited by the required setbacks - meaning on many rural and large-lot parcels, building footprint is effectively controlled by yard setbacks rather than an explicit coverage cap. Section 4710 (Coverage Specification) states that maximum lot coverage is established to regulate the intensity of development and may be specified by the Development Designator. Because the actual percentage or square-footage cap varies by parcel and zone, owners must check the Coverage Designator in their property's zoning or consult PDS. Coverage limits work together with the Setback (Section 4810) and Height (Section 4610) designators that together make up a parcel's development regulations.