Cost to build an ADU at your address
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Detached ADUs, San Francisco · single-unit · 51 projects · 29 completed
Detached: a new free-standing building on the lot.
Declared on permits: $137k–$275k · median $192,111
$172k–$344k estimated total
1 year 5 months to build.
Builders’ bids, Bay Area 2026: $250k–$500k (construction only; add $15k–30k utility connections; Custom Home, Hamilton Exteriors)
Recent projects
- 319A Flood Ave · 2026 · Barcci Builders INC$190,000
- 79A Everson St · 2026 · Cal Am Construction INC$300,000
- 421 Lakeview Ave · 2026$101,728
- 1120 Athens St · 2026 · Nest Builders$450,000
- 1704A Irving St · 2026$340,607
- 4179A 26th St · 2026 · Armour Construction$192,111
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.