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Check an ADU contractor license in five minutes

By the HyreADU research desk. Last checked .

The short answer

To check an ADU contractor license in California, search the CSLB’s Check a License tool by license number, business name or personnel name.

Confirm the license is active, the class fits the work (B General Building for a full ADU, C-47 to install a manufactured home), the name matches your contract, and the bond and workers’ compensation entries are current.

Step by step

  1. Ask the builder for the license number, and look for it on the bid.
  2. Search it on the CSLB Check a License page. You can also search by business name or a person’s name.
  3. Confirm the status is active and the expiration date is in the future.
  4. Confirm the class: B General Building for a full ADU, per the CSLB’s ADU fact sheet.
  5. Confirm the business name matches the name on your contract.
  6. Read the bond and workers’ compensation entries, and any listed actions or complaints.

What the record shows

A CSLB license page shows the issue and expiration dates and status, the classifications, the contractor’s bond, and workers’ compensation coverage or an exemption. Some records list disciplinary actions. A salesperson who sells home improvement work may hold a separate Home Improvement Salesperson registration, which you can also search.

Red flags

  • No license number on the bid.
  • A name on the license that differs from the contract.
  • An expired or suspended license.
  • A specialty C class only, for a whole ADU.
  • A workers’ compensation exemption when the firm has a crew.

Beyond the license

A license shows legal standing, not ADU skill. Look for ADU permits in the firm’s name in your city; our permit contractor index covers five California jurisdictions, and the enforcement record covers actions against ADU contractors. Then work through the questions to ask an ADU builder.

What to do next: read the questions to ask an ADU builder, check what decides ADU cost, then tell us about your project. Matching is not live yet, so we reply with information, not a quote.

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Questions

What license does an ADU contractor need in California?

The CSLB names B General Building for an ADU, or C-47 to install a manufactured home.

Can I check a license outside California?

Most states have a licensing board lookup. Search your state’s contractor board.

Does a license mean the builder is good?

No. It means they may legally do the work. Check permits on record and references too.

What if a builder is unlicensed?

In California, report it to the CSLB, and do not sign.

Sources

HyreADU is a publisher. It does not design, permit or build ADUs, has no partner builders, and gives no legal, tax or engineering advice. Rules vary by state and city; California rules are labeled as such.