Quick answer
Looking for an ADU contractor? Share your project and property details to request introductions to vetted independent contractors serving your California area. Mr. Nailed It provides matching, not construction, design, permitting, or inspection services.
Request California ADU contractor matches
Provide your California city, property details, planned ADU type, preferred budget range, desired start window, and the help you need. These details help prospective contractor matches assess whether the project fits their services and availability.
- Service area: California, subject to contractor availability in your location
- Project details: new ADU, conversion, or another planned configuration
- Property details: location and relevant information about the existing site
- Planning details: preferred budget range and desired start window
- Next step: request introductions and evaluate each contractor independently
Note: ADU requirements depend on the property and jurisdiction. Confirm current permit, zoning, design, inspection, and energy-code requirements with your local building department before finalizing the project.
Verify a California ADU contractor
The Contractors State License Board licenses and regulates California's construction industry. Its tools let homeowners check a license, find licensed contractors, file complaints, and report unlicensed activity.
- Ask the contractor for the business name and license number shown on the proposal.
- Check the license through CSLB before signing.
- Confirm that the information shown by CSLB matches the contractor and business named in the agreement.
- Save the license results with your bids and contract records.
Compare ADU bids with one checklist
Give every contractor the same project information and request a written proposal. Comparing the same categories makes omissions easier to identify and reduces reliance on a headline price.
| Item | What to record |
|---|---|
| License | Business name, license number, classification, and CSLB status |
| Insurance | Coverage information supplied by the contractor |
| Design and permits | Who prepares plans, submits applications, and responds to corrections |
| Scope | Included work, materials, allowances, and explicit exclusions |
| Subcontractors | Which portions may be assigned to other contractors |
| Schedule | Proposed sequence and assumptions affecting timing |
| Changes | How change orders are described, approved, and priced |
| Payments | Down payment and later payments tied to the contract |
| Closeout | Inspections, final sign-off, lien-release process, and warranty terms |
Ask questions about blank or vague line items. A lower proposal may cover less work, so compare responsibilities, allowances, exclusions, and payment terms before comparing totals.
Define who handles each project phase
- Design: Who prepares plans and handles revisions?
- Permit submittal: Who files documents and responds to plan-check comments?
- Construction: What work is included, and what may be subcontracted?
- Inspections: Who schedules inspections and addresses correction items?
- Closeout: Who handles final documentation, remaining work, and warranty information?
Do not assume these responsibilities are included. Require the proposal and contract to identify what the contractor will handle, what another professional will handle, and what remains the homeowner's responsibility.
Review California contract and payment protections
CSLB states that its home-improvement contract and payment rules apply to all home-improvement projects, including residential accessory dwelling unit construction.
- The down payment should not exceed $1,000 or 10% of the total contract price, whichever is less.
- Later payments must be listed clearly in the contract and based on the value of completed work or materials delivered to the home.
- For rebuilding after a wildfire or another declared disaster, the contractor must use a fixed-price contract rather than time-and-materials or cost-plus terms.
Heads up: Compare the payment schedule with the written scope. Ask about any payment that is not connected to completed work or delivered materials, and review current CSLB guidance before signing.
Use current California ADU guidance
The California Department of Housing and Community Development describes ADUs and Junior Accessory Dwelling Units as options for adding housing. ADUs may also be called granny flats, in-law units, backyard cottages, or secondary units.
HCD's California ADU guidance includes an ADU Handbook updated in March 2026. HCD also notes that local ADU ordinances are optional, so confirm the rules for your address with the appropriate city or county department.
Relevant Government Code sections were renumbered after Senate Bill 477 was chaptered. Use current official guidance rather than relying on older section references.
HCD provides an Accessory Dwelling Unit Portal for submitting technical-assistance requests and potential violations for review.
Plan for California energy standards
California's 2025 Building Energy Efficiency Standards took effect January 1, 2026. Ask the local building department and your design professional which requirements apply to the proposed ADU.
The California Energy Commission provides manuals, forms, software, an Energy Code Support Center, solar assessment tools, a climate-zone map, and information about manufacturer-certified equipment for compliance work.
Research specific California ADU projects
For location- and project-specific planning, see ADU Construction in Los Angeles: Complete Cost & Permit Guide and Garage Conversion to ADU or Living Space in Los Angeles.
Get matched with independent ADU contractors
Mr. Nailed It matches homeowners with vetted independent contractors. It does not build ADUs, prepare designs, issue permits, perform inspections, or guarantee project pricing, schedules, contractor availability, or approvals.
Frequently asked questions
How do I verify a California ADU contractor?
Request the contractor's license number and check it through CSLB before signing. Confirm that the license information matches the business and contractor named in the proposal.
What should I compare in ADU proposals?
Compare license information, design and permit responsibilities, included work, exclusions, allowances, subcontracting, schedule assumptions, change orders, payment milestones, closeout duties, and warranty terms.
How much can an ADU contractor request as a down payment?
For a home-improvement project, the down payment should not exceed $1,000 or 10% of the total contract price, whichever is less, according to CSLB.
Which California energy standards apply?
The 2025 Building Energy Efficiency Standards took effect January 1, 2026. Confirm the requirements for your ADU with the local building department and your design professional.
How does Mr. Nailed It help?
Mr. Nailed It matches homeowners with vetted independent contractors. It does not perform construction or approve permits. Contractor availability and project fit depend on the location and information submitted.