Cost to build an ADU at your address
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Converted ADUs, San Francisco · single-unit · 729 projects · 383 completed
Converted: a new unit within existing space: garage, basement, ground floor, or a rebuilt structure.
Declared on permits: $78k–$185k · median $127,700
$97k–$232k estimated total
1 year 1 month to build.
Builders’ bids, Bay Area 2026: $80k–$150k (garage conversion bids, 400–500 sq ft; basements run higher; Hamilton Exteriors, Custom Home)
Recent projects
- 1342A 21st Ave · 2026 · Kelun Construction$66,859
- 112 Sussex St · 2026 · Thomas Peter J Construction$80,000
- 643 Spruce St · 2026 · M H Construction Management Co$90,000
- 880A Pacheco St · 2026 · Cej Construction LLC$118,611
- 3736 Irving St · 2026$250,000
- 1380B Revere Ave · 2026$53,754
Average cost to build an ADU in San Francisco
Estimated total · single-unit projects
- Converted · 729 projects · 1 year 1 month to build$97k–$232kmedian $160k
- Detached · 51 projects · 1 year 5 months to build$172k–$344kmedian $240k
- Attached · 75 projects · 1 year 6 months to build$163k–$356kmedian $259k
- Junior ADU · 13 projects · 10 months to build$122k–$211kmedian $188k
How we get these numbers. Each is the value declared on the building permit, divided by 0.8. Permits list construction cost only. Design adds about 10% and permit fees 6 to 9% (sf.gov). At the minimum, the declared permit value is about 80% of the total.
Why it is a range. Square footage, site conditions, foundation and utility work, finishes, and whether the unit is new or converted all move the price. The range covers the middle half of projects.
Get a precise estimate for your address. We check your site conditions, square footage and finish level, and give you a precise estimate before builders bid.