Cost to build an ADU at your address
We check your site conditions, square footage and finish level, and show you a precise estimate.
Junior ADUs, San Francisco · single-unit · 13 projects · 4 completed
Junior ADU: up to 500 sq ft inside a single-family home.
Declared on permits: $98k–$169k · median $150,000
$122k–$211k estimated total
10 months to build.
Recent projects
- 2722 Irving St · 2026 · Over The Woodsman Builder INC$242,943
- 538 Peralta Ave · 2026$115,206
- 720 Victoria St · 2025 · O Donoghue Construction INC$38,482
- 48A Brentwood Ave · 2025 · Xinrong Construction INC$179,057
- 1134 Felton St · 2025 · W Dragon Plumbing & Development$158,000
- 7915 Geary Blvd · 2024$150,000
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.