Prefab Cost Lab publishes per-city data on what it costs to put a prefab or modular home on a lot in the SF Bay Area: factory pricing, site work, building permit and plan-check fees, development impact fees, SB 9 lot-split rules, and utility connection charges. We built it because this information exists — in city fee schedules, permit portals, and council resolutions — but nobody had pulled it together city by city.
We are an independent publisher. We are not a builder or contractor and we do not perform construction work. If you request quotes through our forms, we may share your information with partner builders who pay us for referrals — see our disclosure.
Editorial researcher covering prefab and modular construction costs, permit and impact fees, and lot-development rules across the SF Bay Area. Compiles per-city figures from city fee schedules and public permit records.
Our research and drafting process uses AI tools under editorial direction. Every page is compiled from city-specific public sources, screened for accuracy against those sources, and rejected when the underlying local data is too thin to support distinct, useful guidance. Our editorial policy explains the sourcing and quality standards each page must meet.