Best ADU Builders in the San Francisco Bay Area

If you are building in the South Bay or on the Peninsula and you want the safest pair of hands, this is it. The license goes back to February 1992, which is the longest unbroken record on this page by fifteen years, and it holds up clean: active B-General through March 2028, bond on file, workers comp current. That 1992 date also does something rare in this trade, which is back up the marketing. When Acton says thirty-plus years, the state’s own record agrees.

What I like operationally is that they build site-built ADUs from a curated set of pre-designed plans and they are explicit that this is not prefab. That distinction gets deliberately fuzzed by half this industry. A pre-designed plan set that a plan checker has seen before moves faster than a bespoke set, and you get that speed without giving up a foundation poured on your actual lot.

The review record has improved since I last checked, and I would rather correct myself than leave a stale gap on the page. Google now reads 5.0 across 44 reviews and Houzz reads 4.9 across 31, both read live on August 9, 2026, with 22 more on Yelp. An earlier pass of mine found no verifiable Google presence at all. Two independent platforms in agreement at the top of the scale, on a license that goes back to 1992, is about as much corroboration as this trade offers.

The East Bay is its own build environment. Hillside lots, older housing stock, and three cities with genuinely different review cultures, and a contractor who mostly works Santa Clara County will feel that on your job. Manzanita works almost exclusively in that corridor, Oakland through Berkeley and out to Lafayette and Orinda, and they take on two-story detached ADUs, which a lot of firms quietly decline because the structural and setback work is harder.

The license reads clean. Active B-General since December 2017, bond effective, workers comp current through October 2026, and the same qualifying individual on the record the whole way. One thing to know before you sign: the license is held by Temescal Design Inc, and Manzanita Design Build is the trading name. That is a normal DBA arrangement, not a warning sign, but check that your contract names the entity that holds the paper.

The honest problem is that there is nearly nothing to read. Their Houzz profile is live and carries no reviews, and I could not verify a Google or Yelp record at all. Nine years of licensed work with no public review trail is unusual. It probably reflects a referral-driven practice rather than anything worse, but it does mean you are relying on references you gather yourself.

Villa is the prefab option I can actually stand behind on paper, and the reason is a detail most comparison pages miss. Their license carries a C47 Manufactured Housing classification alongside the B-General, which is the classification a prefab builder is supposed to hold, and plenty of companies selling “modular” ADUs do not have it. Active since July 2021, bond and workers comp both current when I checked.

The catch is that there is almost nothing to read. No Google presence I could verify, no Yelp record, no Houzz. For a company founded in 2019 that is unusual, and it means you are buying on the strength of the product and the paperwork rather than on other homeowners’ experiences. If predictable pricing and a fixed scope matter more to you than a thick review file, that trade is defensible. Just go in knowing you are making it.

One housekeeping note. When you look Villa up yourself you may hit a second record, #1139781, registered as a sole ownership at the same San Francisco address and marked inactive. That is not the operating license. The one doing the work is #1077688.

Type Five is an architect and a general contractor in the same company, running a deliberately standardized ADU process instead of treating every project as a blank sheet. When it works, that setup removes the worst handoff in this business, the one where the architect draws something the builder then tells you is unbuildable at your budget. Berkeley pre-approving one of their designs in 2025 is a real signal too, because a pre-approved design skips a chunk of plan check.

Now the thing I would not sign without resolving. Their contractor’s bond carries a cancellation date of September 1, 2026, which is a month after I pulled this record. A bond that lapses without a replacement puts the license into suspension automatically, and a suspended contractor cannot legally contract with you. It is very often just a carrier switch and nothing more. Pull the license yourself before you sign anything and confirm a current bond is showing.

Beyond that it is a young company, licensed January 2022, with no verifiable review record on any of the three platforms. The press coverage is real but press coverage is not a reference. Ask for three completed East Bay addresses and two homeowners you can call.

Samara is the design-forward end of Bay Area prefab. Five sizes up to about 950 square feet, all-electric, fire-resistant, and a genuinely considered product rather than a shed with a kitchen in it. The license verifies clean: active B-General since March 2023, bond effective April 2026, workers comp running through April 2027.

One licensing detail worth understanding, because it separates the two prefab options on this page. Villa carries C47 Manufactured Housing alongside its B classification. Samara holds B only. That is not a violation and it does not make them unlicensed, it reflects a different delivery model, but if you want the classification the state specifically maintains for factory-built housing, Villa is the one that has it. Ask Samara directly how their units are certified and who signs off on the factory work.

There is also a date on the record I would want answered before signing. Their Bond of Qualifying Individual carries a cancellation date of September 2, 2026. That bond exists because the qualifying individual no longer owns 10 percent or more of the company, which is the condition that normally waives it. If it cancels without a replacement on file, the license goes into suspension for lack of a qualifier bond. Most of the time this is a carrier change and nothing happens. Check it anyway.

The other thing to hold in your head is what the published price actually covers. Roughly $314 per square foot in 2026 is unit-only. Foundation, site work, utility runs and installation land on top, and on a difficult lot that gap is not small. I would rather they published a delivered range, but publishing anything at all puts them ahead of most of this category.

This is the hardest entry on the page to place, and I want to be straight about why. On volume, nobody here is close: roughly 227 Yelp reviews and 110 on Houzz reading 5.0 when I pulled it, on a license that has run continuously since November 2006. That kind of record only comes from finishing a lot of jobs, and their garage-conversion volume in San Jose is genuinely useful if you are working an older lot where converting beats building new.

Then there is what the state’s record says. The license is active, but it carries two things most do not. There is a $50,000 disciplinary bond on file, effective November 2023, which CSLB requires as a condition attached to a license following disciplinary action. And the record carries public complaint disclosure, meaning CSLB is publishing complaint information rather than holding it back. Neither of those makes them unlicensed and neither stops them contracting with you legally. Both are things I would want to have read before I handed anyone a deposit.

So they rank, because an active license with a deep review record is a real thing and pretending otherwise would be dishonest in the other direction. They rank last, because a disciplinary bond is not a paperwork quirk. Open the complaint disclosure on their CSLB record yourself, read what is actually in it, and decide whether the volume outweighs it for your project. That is genuinely a judgment call and not one I can make for you.