ADU Surveys in San Francisco, CA

San Francisco does not write a separate survey rule for ADUs, but its general plan-submittal standard reaches most of them. Planning's guidelines require a site survey, signed by a California-licensed surveyor, for new buildings or whenever staff request one, and they state that a site plan cannot substitute for it. A detached rear-yard ADU is a new building. The required survey content is specific: the curb elevation, the existing grade at the midpoints of the adjacent front walls, and the roof, eave, and peak elevations of the neighboring buildings, along with property lines and setbacks. For ADUs inside an existing building — the garage and ground-floor conversions that make up the bulk of the city's ADU permits — the site plan must still dimension the distance from existing walls to the property lines, and on a 25-foot-wide zero-lot-line lot that dimension is the whole question. A wall that is actually six inches over the line is a problem no site plan drawn from the assessor's map will reveal.

Those lines are harder to find here than anywhere else in the region. Most of the city's records before 1906 burned, monuments in the eastern half of the city were re-established afterward, and a century of rebuilding has left row-house walls, fences, and rear-yard sheds that only loosely track the record. We resolve the boundary from the city's monument lines on CCSF-CS13, recovered evidence, and the chain of title, then locate the existing house, garage, and neighbors' walls against it. On hillside lots — Bernal Heights, Glen Park, the Sunset's slopes above Golden Gate Heights — rear yards are often steep enough to bring the Slope and Seismic Hazard Zone Protection Act's 4:1 average-slope threshold into play for a detached unit, which makes a laser-scanned topographic survey of the yard part of the same visit. Our terrestrial laser scanner captures the lot, the existing building, and the neighboring elevations Planning asks for in one setup, and the point cloud gives the architect measured existing conditions for the conversion itself.

Deliverables are the signed site survey, a layered DWG base map, staked property corners, and the point cloud. Under DBI review, contractors often ask us back to verify foundation forms against the approved setbacks before the pour. See our San Francisco topographic surveys and as-built surveys.