An ADU project often involves a designer or architect, a contractor and your city or county. This section explains what to check before you sign anything.
What this topic covers
In California, the Contractors State License Board (CSLB) licenses the people who build ADUs. A few checks on the license, the contract and the payment schedule protect you from the most common problems.
Key facts
- CSLB says "building an ADU is considered a home improvement project under the Contractors State License Law," so a written contract is required.
- A B (General Building) contractor can build or install an ADU. A C-47 contractor can install a manufactured ADU built off site.
- Under Business and Professions Code section 7159, a down payment may not exceed $1,000 or 10 percent of the contract price, whichever is less.
- CSLB advises getting at least three bids that cover the same scope.
- You have three days from signing to cancel, five days if you are 65 or older, and seven days in disaster zones.
Guides in this hub
- Hiring an ADU builder: how to check a CSLB license: license classes, the contract, payment limits, red flags and questions to ask.
Related reading: the permit process explains who pulls the permit, and ADU cost in Los Angeles explains how to compare bids.
Before you sign
- Check that the license is active at cslb.ca.gov and the class matches the work.
- Match the name on the license to the name on the contract.
- Ask to see the pocket license and insurance, and request references from similar jobs.
- Get every change order in writing, and tie payments to completed work.
Red flags
CSLB warns against "unlicensed individuals offering cash deals or vague estimates." Other warning signs are a large deposit request, pressure to sign the same day, no written contract, and a builder who will not let you check the license.
We are not a contractor and do not recommend or refer builders.