How to Choose the Right ADU Contractor in California: A Homeowner’s Playbook (and Where It Runs Out)

The five checks below are public, free or low-cost, and actionable by any California homeowner. Together they filter out roughly 70% of failure-prone contractors before a contract is ever signed.

The CSLB license lookup tool is the legal floor. What to look at:

• License status: active (not suspended, revoked, expired, or “bond canceled”).
• License classification: B-General Building for new ADU construction. Specialty licenses are not interchangeable.
• License issue date: continuously active for at least 5 years under the current business name.
• Responsible Managing Officer / Employee (RMO / RME): has the RMO been consistent for at least 24 months? Frequent RMO changes are a leading indicator of operational instability.
• License bond: active at the mandated $25,000 minimum, which under SB 607 became effective January 1, 2023. The $25K is a total recovery cap across all claims, not per-claim (CSLB Fast Facts License Bond 2025).
• Disciplinary history: the CSLB publishes accusations, citations, and revocations in a public record. Three or more actions in 5 years is a red flag.

The BBB record adds the consumer-side complaint dimension that CSLB does not cover. What to look at:

• Complaint volume over 36 months (not lifetime — a 30-year-old contractor with 2 complaints is fine; a 4-year-old contractor with 8 is not).
• Resolution pattern (did the contractor respond and resolve, or did complaints go unanswered?).
• Substantive themes (abandonment, change-order abuse, lien filings, communication failures).

BBB ratings on their own are unreliable as they are paid-membership-influenced. The complaint detail underneath the rating is the signal.

Every contractor produces references. Most references are friendly. What separates a useful reference from a useless one is what you ask for upfront:

• Three completed ADU projects in your specific city in the past 24 months, with the city permit numbers for each.
• The homeowner’s contact information for each project, with permission to call.
• The original contract price and the final all-in cost, including all change orders.

The permit numbers are the load-bearing data point. A city permit number can be cross-checked against the building department’s public record. A homeowner contact can be called. A pair of numbers (original price, final price) tells you the change-order pattern.

What to ask the references

1. Did the project finish on the contract timeline? If not, what slipped and by how much?
2. How many change orders were filed? What was the total dollar value?
3. Were there any inspection corrections? How many rounds at plan check?
4. Would you use this contractor again?
5. What is the one thing you wish you had known before signing?

A reference who hesitates on question 4 is more informative than one who gives a clean yes.

Photos lie. Renderings lie. A walked project tells you what the contractor’s actual work looks like 12 to 24 months after completion, when the finishes have settled and any quality issues have surfaced.

What to look at:

• Finish quality at the boring details: baseboard returns at corners, door hardware alignment, tile grout lines, exterior trim caulking.
• Settlement cracks in stucco, drywall, or foundation.
• HVAC and electrical access — can the homeowner reach panels and filters without contortion?
• The homeowner’s read of the contractor mid-project: communication, change-order behavior, schedule adherence.

A contractor who will not arrange a walked project for a serious bidder is filtering themselves out for you.

The construction contract is the document that controls money flow for the next 6 to 18 months. Five clauses consistently move money toward the contractor:

1. Payment schedule — front-loaded draws (10/40/40/10) put homeowner cash ahead of work in place. Inspection-anchored milestone payouts are the right structure.
2. Change-order pricing — without pre-defined unit pricing for common categories, change orders become open-ended.
3. Allowances — “$8,000 allowance for cabinets” without a specified product line gives the contractor the overage.
4. Liquidated damages — most contracts impose damages on the homeowner for delayed payment but nothing on the contractor for delayed delivery.
5. Lien waivers — every progress payment should require conditional and unconditional lien waivers from subs. Without these, the homeowner remains exposed under California Civil Code §8400 et seq. even after paying the GC in full.

A California-licensed construction attorney charges $400 to $1,500 to review the contract. On a $200K to $400K contract, the review consistently moves $10K to $50K of risk back to the contractor where it belongs. This is the single check on this list where outside expertise reliably pays for itself.