The checklist
How to choose a designer-ADU builder
Nearly every general contractor in the Bay Area will happily build you an ADU. Far fewer will build you one that looks designed. These are the eight criteria that tell them apart — and the same standard used to assemble the curated shortlist.
The problem with how most people choose
The default process is to collect three bids and take the middle one. It feels prudent and it is close to useless, because a bid measures one thing: what a company is willing to charge for a scope you have not yet defined. It measures nothing at all about whether the finished building will look like the images that made you want an ADU in the first place.
The cost of getting this wrong is not a bad quarter. It is a permanent structure in your backyard that you will look at every day, that rents for less than you hoped, and that a future buyer will quietly discount. You cannot fix a roofline with a change order after framing.
So evaluate the builder before you evaluate the price. Here is the standard.
01
Portfolio depth, not portfolio volume
Look for at least several completed ADUs, photographed from more than one angle, including the approach and the relationship to the main house. Three projects shown properly beats thirty hero shots.
Ask
Can I see every ADU you completed in the last two years, not just the favourites?
Red flag
The same two projects everywhere, renders instead of photographs, or interiors only with no exterior ever shown.
02
A visible point of view
Good designer-ADU builders have a recognisable approach — roof forms they favour, a materials palette they detail well, a consistent way of handling entries. Consistency is evidence of intent.
Ask
What do your ADUs have in common, and why do you build them that way?
Red flag
A portfolio that looks like six different companies, or an answer that is only about price and speed.
03
Real design hours on your specific lot
The difference between a designed unit and a placed unit is whether anyone studied your lot: orientation, the view from the main house, where the sun lands, where the courtyard forms. Stock plans are not automatically bad, but adapting one without studying the site is.
Ask
Walk me through your design phase. Who draws it, how many hours, and how many options do I see?
Red flag
Design is free, design is one meeting, or design means picking a model from a catalogue.
04
Permit handling that is theirs, not yours
Delay usually comes from incomplete submittals and unnecessary exception requests. A builder who runs permits routinely will describe the process specifically and know when a design choice pushes a project out of ministerial review.
Ask
Who submits, who responds to corrections, and how many correction cycles did your last three projects take?
Red flag
Vagueness about the process, or telling you the city is the reason projects take forever.
05
A transparent, complete scope
The bid should state what it includes and, more importantly, what it excludes: design fees, engineering, Title 24, permit and impact fees, utility upgrades, trenching, grading, hauling, landscaping, appliances.
Ask
What are the exclusions and the allowances, in writing?
Red flag
A single lump-sum number with no breakdown, or a bid that is dramatically lower than others with no explanation.
06
Communication you can already feel
How a builder behaves during the sales conversation is the best available preview of how they behave during construction. Response time, willingness to say I don't know, and whether they answer the question you asked.
Ask
Who is my day-to-day contact once we start, and how often will I hear from them?
Red flag
Pressure to sign, discomfort with detailed questions, or a salesperson you will never see again after the deposit.
07
Reviews read for pattern, not score
A 4.9 average tells you little. Read the three-star reviews and the responses. You are looking for recurring themes — schedule slippage, change-order surprises, subcontractor quality — and for how the company responds when things go wrong.
Ask
Can I speak to two clients whose project went sideways, not just two happy ones?
Red flag
A wall of short five-star reviews posted in the same week, or defensive replies to reasonable criticism.
08
Licensing, insurance and contract basics
Active California contractor's license, general liability and workers' compensation, a written contract with a defined schedule, a progress-based payment schedule tied to milestones, a change-order process and a warranty.
Ask
License number, proof of insurance, and a sample contract with the payment schedule?
Red flag
Large up-front deposits, cash discounts, or reluctance to put the schedule in the contract.
How to use this
Score each builder out of eight before you look at a single number. In practice most firms fail on the same two criteria — design hours and scope transparency — and those two predict almost everything else about how the project will go.
This is also the exact standard behind the curated builder shortlist. A firm appears there only after it clears these eight points, and each entry says which criteria it clears most convincingly. If it does not clear them, it does not get listed — regardless of how well known it is.
Frequently asked questions
- How do I know if a builder can deliver a designer ADU?
- Judge the portfolio before the pitch. Look for several completed ADUs photographed from the approach, a recognisable and consistent point of view across projects, and a described design phase with real hours spent on your specific lot. A builder who cannot show you exteriors, or whose design phase is a single meeting, will hand you a competent box.
- Should I hire an architect and a contractor separately, or a design-build firm?
- Both models produce good ADUs. Separating design from construction gives you an advocate whose only job is the design, but adds coordination work and usually cost. Design-build is simpler and often faster, but the quality depends entirely on whether that firm has a genuine designer rather than a drafter. Evaluate the actual design capability, not the label.
- What questions should I ask an ADU builder on the first call?
- Ask to see every ADU they completed in the last two years; ask what their ADUs have in common and why; ask who draws the design and how many hours it takes; ask how many permit correction cycles their last three projects needed; and ask what is excluded from the bid. The quality and specificity of these five answers separates the shortlist from the rest.
- Is the cheapest ADU bid ever the right choice?
- It can be, but only after you have confirmed that all three bids cover the same scope. The most common reason a bid is dramatically lower is that it excludes design, engineering, permit fees, utility upgrades, or site work that the others include. Normalise the scope first, then compare.
- How many builders should I get bids from?
- Three is the usual advice and it holds up, provided all three clear the checklist first. Collecting bids from builders you would never actually hire wastes your time and theirs, and encourages you to anchor on a number from someone who cannot deliver the result you want.
Want the shortcut?
Tell me about your lot and the look you're after, and I'll point you toward builders who already clear this checklist.
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