ADU Surveys in Vallejo, CA

Vallejo's application checklist treats surveying as part of the ADU vocabulary. The required site plan must show property lines with dimensions and arc lengths, every easement by its nature — water, sewer, drainage, access, and more — utilities, setback dimensions, significant site features like swales and hills, structures within 50 feet beyond the property lines, and the lowest finished floor elevation, with the flood zone stated on the cover sheet. Boundary and topographic surveys appear as named checklist items the Planning Division can require case by case, and the boundary survey spec is explicit: prepared by a licensed California surveyor (or authorized civil engineer), with easements shown. The topographic spec is equally concrete — existing topography and proposed grading extending 50 feet beyond the property lines, 2-foot contours on gentle ground, retaining walls with top- and bottom-of-wall elevations. And the city's ADU guide states plainly that a soils report is generally required for all new construction.

Then there is the elevation rule that makes Vallejo unusual: citywide, the lowest finished floor of residential structures must sit at or above 13.50 feet NAVD88 — FEMA's 10-foot base flood elevation for the 100-year storm plus 3.5 feet for sea-level rise. For flatland and waterfront neighborhoods, that turns a backyard ADU into an elevation problem a surveyor answers: existing grade, proposed floor elevation, and FEMA zone delineation with base flood elevations labeled on the plans where a Special Flood Hazard Area touches the parcel. Up in the hills — Glen Cove, the ridge neighborhoods — the topo and grading side takes over instead. Vallejo's older grid around St. Vincent's Hill adds the familiar boundary caution: Victorian-era lots whose fences and record lines parted ways generations ago.

ADUs over 800 square feet route through Planning zoning review before building permit; all sizes route through multiple departments including the Vallejo Flood and Wastewater District. Records run through the Solano County Recorder in Fairfield. Deliverables are a stamped site plan base map, layered DWG, staked corners, and datum-referenced elevations ready for the 13.5-foot analysis; see also our Vallejo topographic surveys.