Monterey County, CA Fence Regulations: Retaining Walls (2026)

Monterey County Code Chapter 16.08 governs grading, which includes excavation for retaining walls, in the unincorporated area only; incorporated cities such as Salinas, Monterey, Seaside, Marina, Carmel-by-the-Sea, Pacific Grove and King City set their own rules. Section 16.08.040 requires a grading permit from the Building Official for any excavation, subject to listed exceptions. Exception C covers 'an excavation below finished grade for basements and footings of a building, retaining wall or other structure authorized by a valid building permit,' but that exception explicitly does not cover 'any excavation having an unsupported height greater than five feet after the completion of such structure.' In practice, a retaining wall built as part of a permitted structure's foundation stays exempt from a separate grading permit only while its unsupported face is at or under five feet; taller walls trigger the grading permit process, including plan review and, per Section 16.08.030, oversight by a registered civil engineer or engineering geologist.

Section 16.08.320, Cut and Fill Slope Setbacks, adds that the tops and toes of cut and fill slopes must be set back from property boundaries far enough to protect adjacent properties from water run-off or erosion damage, and that 'retaining walls may be used to reduce the required setbacks when approved by the Building Official.' Minimum setbacks otherwise default to Table B of the chapter unless a soils or geology report and the approved grading plan justify a different distance. Any retaining wall work performed without the required grading permit is treated the same as unpermitted grading generally: the site can be posted with a stop-work notice under Section 16.08.430 and all work must halt until a valid permit is issued.