Two Programs, Two Very Different Deals.
San Francisco gives homeowners a choice between a Local Program and a State Program, and picking the right one matters. The Local Program is built for adding units inside existing buildings and can grant waivers from Planning Code requirements like density, open space, rear yard, and exposure. The catch: when the City grants a waiver, the new unit must be registered under a Costa-Hawkins Regulatory Agreement, which makes it subject to rent control. Local Program applicants also must post notice on the property at least 15 days before submitting the application. The details are laid out on SF.gov's Local Program rules page.
The State Program is the opposite: no waivers, no Planning Code discretion, and no rent control triggered by the approval itself. Per SF Planning's Director Bulletin No. 3, State Program ADUs get ministerial review within 60 days of a complete application, are exempt from CEQA, and face no discretionary review. Neighbors cannot slow it down. For a standalone backyard unit like an Abodu, the State Program is almost always the right lane, and it is the one our team uses to keep the process predictable.
Where a Detached Backyard ADU Fits in SF.
Yes, detached backyard ADUs are real in San Francisco, they just do not fit every lot. SF parcels are famously narrow and deep, so the question is whether your rear yard has the room. Under the State Program, SF Planning allows one detached ADU on a single-family lot at up to 850 square feet for a studio or one-bedroom and up to 1,000 square feet for two or more bedrooms, with a height of up to 18 feet plus 2 extra feet to match the primary home's roof pitch, and 4-foot setbacks from side and rear lot lines.
There is a useful SF-specific wrinkle: if you are replacing an existing rear-yard structure, like an old garage or shed, the 4-foot setback does not apply as long as the new ADU sits in the same location and matches the dimensions of what it replaces. A single-family lot can also stack a detached ADU with a converted ADU and a junior ADU, so one property can gain multiple units. Not sure whether your yard pencils? Check your lot and we will map your setbacks and buildable area for you.
Multifamily Lots: San Francisco's Signature Move.
San Francisco's housing stock is mostly multifamily, and the City's ADU rules lean into it harder than almost anywhere in California. Under the Local Program, buildings with four or fewer units can add one ADU plus one detached ADU, while buildings with five or more units, or those doing seismic upgrades, can add an unlimited number of ADUs plus one detached unit, per SF Planning.
The State Program is generous here too: existing multifamily properties can add up to 8 detached ADUs, capped at the number of existing units, and detached ADUs on multifamily lots have no maximum size restriction under the State Program, though the same 18-foot height limit applies. For building owners, that turns underused rear yards and side lots into new rental income at scale. Abodu builds for exactly this scenario; see how we work with multifamily and portfolio owners.
SF Quirks: Rent Control and Historic Buildings.
Two San Francisco-specific issues deserve honest treatment. First, rent control: it attaches to Local Program units when a waiver is granted or when the building's existing rental units are already covered by the Rent Ordinance, via the Costa-Hawkins Regulatory Agreement described on SF.gov. State Program units are not subjected to rent stabilization by the approval itself. If you plan to rent your ADU, this single choice shapes your long-term economics, so make it deliberately.
Second, historic properties: San Francisco has a deep inventory of historic resources, and per SF Planning's State ADU bulletin, ADUs on historic properties must be consistent with standards that prevent adverse impacts on the historic resource. A detached unit tucked in the backyard is often the cleanest way to add housing on a historic lot because it leaves the primary building untouched. Hear from homeowners who have been through it on our testimonials page.
What It Actually Costs.
Custom site-built ADUs in California routinely exceed $250,000 before change orders, and in San Francisco tight access, older infrastructure, and long construction windows push budgets and timelines further. Abodu works differently: transparent published pricing: homes from $234,800 plus a published installation price, an expected all-in from $298,800 that covers design, permits, factory build, delivery, and installation. Your unit is built in a factory while permits move through the City's 60-day State Program clock, so nothing sits idle. See how the process works.