ADUs in the Sunset District: What Fits a 25-Foot Lot

The stock

1940s–60s stucco rows on 25-foot lots

District 4's ADU stock is distinctive: 1940s–60s stucco rows on 25-ft lots — about 2,500 sq ft — with ground-floor garages. That single fact shapes everything. The lot is too narrow for easy side access, the rear yard is shallow, and the convertible volume is not in the garden — it is the garage-and-storage level under the living floors, opening toward the rear.

Inner and Outer Sunset houses share that pattern, which is why the district's permits look the way they do: the work is overwhelmingly alterations to existing buildings, not new structures. Permit types corroborate the type descriptions — 49 of the 55 District 4 permits are additions/alterations/repairs, and only 5 are new construction.

Permit evidence — District 4

What DBI permits actually show for the Sunset

These figures are counted from DBI's own records, not estimated from listings or broker pages. Read the caveats with the numbers — they are part of the evidence.

Type mix, stated exactly with its limit: of the 22 District 4 permits whose descriptions state a type, 18 are interior or garage conversions and only 3 are detached new construction. The other 33 of the 55 do not state a type in their descriptions, and this page does not guess them.

Mandatory caveats. Declared (estimated) cost is an applicant estimate recorded at filing — not a final construction cost, not a bid, and not a guide to what your conversion will cost. SF publishes no per-permit fees in open data, so this page makes no fee claims from permit data. For conversion method — ceilings, egress, underpinning, fire separation — use the basement and lower-level conversion guide; this page deliberately does not repeat the method.

Five District 4 permits, anonymised

Declared (estimated) cost in every row is the applicant estimate recorded at filing — not the final construction cost. The spread itself is the lesson: a bedroom conversion and a full garage-to-two-bed conversion are both “Sunset ADUs” in the data, at very different declared figures, because the starting space and the scope are different.

Reading the record honestly

Standalone, mixed, filed and issued — what the words mean here

Of the 55 District 4 permits, 39 are standalone ADU projects and 16 are mixed with larger projects — filed alongside broader work on the same property rather than as an ADU on its own. Standalone figures are the cleaner read on what a Sunset homeowner's ADU project looks like, which is why the declared-cost medians on this page are given for the standalone set: a median of $60,000 across all 39 filed standalone permits, and $75,000 across the 27 of them that have been issued. Mixed projects carry the cost of the larger work with them, so blending them in would distort the picture in both directions.

The filing pattern by year — 24 filings in 2023, 9 in 2024, 15 in 2025 and 7 in 2026 — needs the same care. The 2026 figure is a partial year at the November 2026 pull date, and filing-to-publication lag means recent filings are the most likely to be undercounted. Read the four years as evidence that District 4 files ADUs steadily, not as a league table of good and bad years, and do not read a trend into a partial year.

Status tells a similar, steadier story: 20 of the 55 are recorded complete and 17 as issued — together, the 38 that have been issued — against 15 still at filed status and 3 in other statuses. A filed permit is a project in the system, not a finished home; an issued or complete one has cleared DBI's process. When you check your own address below, your plan is written for the start of that journey, with the district's real conversion pattern — not a detached-cottage assumption — built into it from the first answer.

District history

The District 4 ADU Incentives Pilot

District 4 has already been a policy focus once. A District 4 ADU Incentives Pilot existed in 2021, run by SF Planning with the District 4 Supervisor's office and ASIAN, Inc., and recorded in Board of Supervisors Resolution 69-22. The pilot is part of why the Sunset has an ADU conversation at all — and why District 4 homeowners should expect their district to stay in the policy spotlight.

One figure needs its label, exactly. A cost band for the pilot is sometimes quoted as $175–250K. That band is press-reported pilot costs (Wind Newspaper, reporting on the pilot) — not an official figure and not permit data. This page does not present it as verified, and you should not budget from it. Budget from your own level's ceiling, egress and structure — the method is in the conversion guide.

Your options on a Sunset lot

Convert first, sell separately if eligible, detached rarely

Sell the unit as a condo — the District 4 push

District 4 is part of San Francisco's AB 1033 conversation: building an ADU and, where the strict eligibility test is met, selling it separately as a condo. The test — programme, application date, lot size, one ADU only, no JADUs — is exact, and no page can promise you pass it. Read the full test on the AB 1033 condo-conversion guide and check your property against it.

Two detached ADUs on a 25-foot lot? Usually no

Honest answer for most Sunset lots: no. Two detached structures, with setbacks, on a 25-ft-wide, roughly 2,500 sq ft lot behind an existing house, does not fit in the ordinary case — which is exactly what the permit record shows, with only 3 detached projects among the 22 type-stated District 4 permits. What changes on Jan 1, 2027, and the lots where two detached can work, are covered on the two-ADUs-2027 guide. In the Sunset, plan on the conversion first.

Rent: read this before you convert a tenant's garage

A Sunset garage is often a tenant's parking or storage — a housing service under the Rent Ordinance. Whether your new unit is rent controlled, and what removing a service can cost you, is decided on the rent-control page. Read it before the design, not after it.

Questions, answered

Sunset ADUs, plainly

San Francisco guides

Related guides

Check your Sunset address

Your lot, your ground floor, your answer

The checker is pre-set to San Francisco. Tell us your Sunset address and what your ground floor does today — garage, storage, or already living space — and your plan starts from the District 4 pattern: conversion first, services checked, detached only if the lot honestly allows it.