ADU Surveys in Antioch, CA

Antioch keeps its ADU paperwork lean: the packet asks for a site plan with lot size, dimensions, and property lines, every building with dimensions, driveways and parking, all easements, and a north arrow. No survey requirement, no topo trigger — on paper. But two details reward accuracy. First, Antioch's objective design standards for larger new-construction ADUs include a privacy rule keyed to distance: window and door openings facing a property line closer than 30 feet pick up glazing requirements, so where the lines actually run changes the elevations, not just the site plan. Second, the state's 4-foot setbacks are measured from legal boundaries that Antioch's housing stock tracks loosely — the city runs from an 1850s rivertown grid downtown (the oldest incorporated city in the county) through mid-century tracts to the newer southeast hills, and each era contributes its own flavor of fence-line drift.

The southeast side adds terrain. Lots climbing toward the Black Diamond Mines edges and the Sand Creek corridor carry real slope, where grading, drainage, and retaining decisions need measured ground even though the ADU packet never says the word "contour" — and where field inspectors frequently require a surveyor to verify foundation forms against approved setbacks before the pour. Antioch also operates a legalization program for unpermitted units, and bringing an existing structure into compliance starts with documenting exactly where it sits relative to the lines. Our laser-scanned site survey covers all of it in one visit: boundary from record research, structures and hardscape mapped, easements of record placed on the plan, and elevations wherever the lot has fall worth designing around.

Records run through the Contra Costa County Recorder in Martinez. Deliverables are a stamped base map, layered DWG, and staked corners; for slope-driven projects see our Antioch topographic surveys.