Choosing who builds your ADU is really two choices made together: the path the project takes from idea to finished unit, and the company that walks it. The path decides how many parties you manage and who answers when something goes wrong. The company decides whether the work is done properly and on paper. This note covers both, in the order we would think them through.
Design-build, prefab or standard plans
There are three common routes to a finished ADU in Los Angeles, and each fits a different kind of owner and lot.
Design-build. One company handles the lot review, the drawings, the permits and the construction. You sign one contract and have one point of contact. The advantage is that the people drawing the unit are the same people who have to build it, so cost is part of the design conversation from the first sketch. The trade-off is that you are trusting one firm with the whole project, which makes checking that firm more important.
Prefab or factory-built. The unit, or large panels of it, is built off site and set on a foundation prepared on your lot. The factory portion can be predictable. What is easy to underestimate is everything that still happens on site: the foundation, the crane or delivery access, the utility trenching and connections, and the permit and inspection steps. Ask any prefab company which of those it covers and which it leaves to you or to a separate contractor.
Standard or pre-approved plans. The City of Los Angeles and a number of other cities offer plans that have already been reviewed, which can shorten plan check. You still need someone to fit the plan to your lot, handle site work and utilities, and build it. A standard plan works best on a lot that suits it without major changes.
These routes are not exclusive. A design-build firm can build from a pre-approved plan, and some prefab units go through a design-build contractor for the site work. What matters is that you know who is responsible for each step, in writing.
License, insurance and ADU experience to check
Whatever route you choose, the company building the unit has to hold an active California contractor license, usually a general building (B) license for an ADU. The Contractors State License Board lets you look up any license number online. Check that the license is active, that the name matches the company you are talking to, and whether there are any disciplinary actions listed.
Ask for proof of general liability insurance, and confirm the company carries workers' compensation coverage if it has employees. The license lookup shows workers' compensation status as well.
ADU experience matters because the rules differ from a standard remodel. A builder new to ADUs may not know which state rules a city must follow, how utility connections for a second unit are handled, or what the final inspection for occupancy requires. Ask how they approach the lot review, how they decide between the four ADU types, and how they handle plan check corrections.
What the contract and payment schedule should say
A written contract protects both sides. For an ADU, it should state clearly:
- The scope of work, including who handles design, engineering, permits, utilities and site work.
- What is excluded. City fees, utility company charges and unforeseen conditions below grade are common exclusions, and you want them named, not discovered.
- A payment schedule tied to completed work. Payments should follow progress: the foundation, framing, rough inspections and so on, not dates on a calendar.
- The down payment, which California limits on home improvement contracts.
- How change orders are priced and approved, in writing, before the extra work is done.
- The start date and the conditions that affect the schedule, such as permit issuance.
Read the contract with the scope in mind. A low price that leaves the utilities or the site work out is not a low price.
Questions to ask before you sign
Use these to compare builders side by side:
- Which ADU types would you consider for my lot, and why?
- Who prepares the drawings, and who answers plan check corrections?
- Who is responsible for the utility connections, and is a panel upgrade likely?
- What exactly is excluded from the price?
- How are payments tied to progress on the job?
- Who will be on site day to day, and who do I call with a question?
- Who schedules and attends the inspections, through final?
Clear answers to these tell you more than a sales presentation. Vague answers about utilities or exclusions usually mean those costs will appear later.
Where Cedarline fits
Cedarline Design Build is a design-build contractor based in Woodland Hills. We start every ADU with a lot review, compare the four types for your property, and then draw, permit and build the unit under one contract. You can read more on our ADU construction page, or see how we approach new construction when the whole lot is being planned at once.