Cost to build an ADU at your address
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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.