Red Flags to Watch for When Hiring an ADU Contractor
ADU projects run $150,000 to $400,000 or more. At that price, choosing the wrong contractor is not just frustrating — it can cost tens of thousands of dollars to undo, delay your project by months, or leave you with an unpermitted structure that cannot be legally rented. Here are seven warning signs to catch before you sign anything.
Note: This article is for informational purposes only and does not constitute legal or contractor licensing advice. Consult a licensed attorney or the California State License Board if you have concerns about a specific contractor or contract.
Quick Answer
Common red flags when hiring an ADU contractor include no valid CSLB Class B license, deposit requests exceeding 10% of the project total or $1,000 (whichever is less), no written bid with line-item costs, no verifiable ADU references, and pressure to sign without review time. Any single flag warrants a closer look.
Why ADU Projects Attract More Contractor Risk
ADU construction is more involved than most residential remodels. It typically includes structural work, electrical and plumbing from scratch, separate utility connections, permit coordination across multiple city departments, and often custom architectural plans. General contractors with limited ADU experience frequently underestimate costs and timelines — and some take on ADU jobs without the permitting background those projects require.
California's ADU law changes starting in 2020 created a large surge in demand and brought contractors of every quality level into the market. Knowing the warning signs helps you filter out poor fits before you spend hours getting bids.
7 ADU Contractor Red Flags to Watch For
1. No valid CSLB license — or one you cannot verify
ADU construction in California requires a valid license from the California State License Board. For most ADU work, that means a Class B General Building Contractor license. You can search any contractor at contractors.state.ca.gov by name or license number. If the license doesn't appear, is expired, is suspended, or covers a classification that doesn't match ADU work, stop there. An unlicensed contractor cannot legally pull permits in most California jurisdictions, and you have limited legal recourse if work is defective.
2. A deposit request above the legal limit
California Business and Professions Code Section 7159 caps the initial deposit at 10% of the total contract price or $1,000, whichever is less. On a $300,000 ADU project, the legal deposit is $1,000 — not $15,000 or $30,000. A contractor who asks for a large upfront payment before any work begins is either unaware of state law or choosing to ignore it. Both outcomes raise questions about how they will handle the rest of the project.
California law note: BPC Section 7159 governs home improvement contracts, which include ADU construction. The deposit cap is $1,000 or 10% of the contract price, whichever is less. Verify current requirements at leginfo.legislature.ca.gov.
3. No written bid, or a bid with no line-item breakdown
A bid that says "ADU construction: $280,000" with nothing further is not something you can evaluate. You cannot compare it against other bids, identify where costs are higher or lower, or spot substitutions or additions after the contract starts. Ask for a breakdown by phase or trade: site prep, foundation, framing, roofing, electrical, plumbing, HVAC, drywall, finishes, and permits. A clear list of exclusions matters just as much. Contractors who resist putting specifics on paper often have good reason for the vagueness.
4. Cannot provide references for completed ADU projects
Any contractor who has built ADUs should be able to give you two or three past client contacts with similar project types. If they deflect with "clients prefer privacy" or offer testimonials you cannot verify, ask again. Good ADU contractors are willing to connect you with past clients. Reluctance to provide references usually means there are few completed projects to point to — or that past clients were not satisfied enough to serve as references.
5. Pressure to sign quickly
"We have another client interested in this slot" or "this price is only good until Friday" are sales tactics. ADU construction is a commitment worth $150,000 to $400,000 or more. A contractor who pressures you to sign without time to review the bid, call references, and consult with others is not respecting the size of the decision. Take the time you need. If a contractor moves on because you took a week to decide, that is a contractor worth letting go.
6. Suggests skipping permits
There is no legal path to build an ADU in California without permits. A contractor who suggests otherwise — framing it as a way to save time or money — is either uninformed about California ADU law or willing to help you build an unpermitted structure. Unpermitted ADUs cannot be legally rented, may trigger code enforcement fines, and create serious title and financing problems when you sell. The permit process also includes inspections that catch construction errors before they become expensive problems.
7. No proof of insurance
Ask for a certificate of insurance showing current general liability coverage and workers' compensation. General liability protects you if the contractor's work damages your property or a neighbor's. Workers' comp covers injuries to workers on your property — without it, an injured worker can potentially pursue a claim against your homeowner's insurance. Verbal assurances are not enough. Ask for the actual certificate, check that the policy dates are current, and confirm the coverage amounts are reasonable for a project of your scope.
What to Do When You Spot a Red Flag
One red flag does not always mean you should walk away immediately, but it should prompt a direct conversation. Ask the contractor to explain. A good contractor will have a clear, reasonable answer. If the explanation feels evasive, if they get defensive, or if you notice multiple flags at once, move on. There are experienced ADU contractors in San Diego who treat proper licensing, insurance, and written contracts as basic professional standards.
If you believe a contractor has acted illegally — demanding an illegal deposit, performing unlicensed work, or misrepresenting their credentials — you can file a complaint with the CSLB at contractors.state.ca.gov.
Before You Sign: A Quick Checklist
- ✓Verified the contractor's CSLB license is active and carries the right classification
- ✓Confirmed the deposit request is at or below $1,000 (or 10% of the contract price, whichever is less)
- ✓Received a written, itemized bid — not just a lump-sum total
- ✓Spoken with at least two references from completed ADU projects
- ✓Taken adequate time to review the contract without being pressured
- ✓Confirmed the contractor will pull all required permits
- ✓Received a current certificate of insurance with general liability and workers' comp
Related Guides
Frequently Asked Questions
How do I check if an ADU contractor has a valid California license?
Visit contractors.state.ca.gov and search by company name or license number. You can see whether the license is active, what classification it carries, and whether any disciplinary actions have been filed. ADU construction typically requires a Class B General Building Contractor license.
What is the legal deposit limit for contractors in California?
California Business and Professions Code Section 7159 limits the initial deposit to 10% of the total contract price or $1,000, whichever is less. On a $300,000 ADU project, the legal deposit is $1,000. A contractor who asks for $20,000 or $30,000 upfront is violating state law.
What insurance should an ADU contractor carry?
Ask for a certificate of insurance showing current general liability coverage and workers' compensation. General liability covers damage the contractor's work causes to your property. Workers' comp covers injuries to workers on your property. Get the actual certificate, not a verbal assurance, and check that the policy dates are current.
What should be included in a written ADU bid?
A written bid should break out labor and materials by phase or trade: site prep, foundation, framing, roofing, electrical, plumbing, HVAC, insulation, drywall, finishes, and permits. It should also include a payment schedule, project timeline, and a list of what is specifically excluded from scope.
Is it legal to hire an unlicensed contractor for a smaller ADU project?
In California, contractors must hold a valid CSLB license for projects valued at $500 or more in combined labor and materials. ADU projects almost always exceed that threshold. Working with an unlicensed contractor voids most consumer protections and may make it impossible to obtain required permits.
What if a contractor says my ADU doesn't need permits?
All ADU construction in California requires permits. A contractor who suggests otherwise may not understand California ADU law, may be trying to avoid inspections, or may be pricing work that doesn't account for required steps. Unpermitted ADUs cannot be legally rented and create serious title and financing problems when you sell.
Disclaimer: This article is for informational purposes only and does not constitute legal, contractor licensing, or construction advice. Requirements vary by project type, city, and contract scope. Consult a licensed attorney or the California State License Board before making decisions about your ADU project or contractor relationships.
Sources
- California Contractors State License Board — License lookup and complaint filing: contractors.state.ca.gov
- California Business and Professions Code Section 7159 — Home improvement contract requirements: leginfo.legislature.ca.gov
- California Department of Housing and Community Development — ADU resources: hcd.ca.gov
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