- Start with verifiable basics: an active California license in the right classification, workers' compensation, general liability, and a certificate of insurance naming you.
- Commercial work is different from residential service. Ask about roof and crane work, refrigeration, code compliance, documentation, and after-hours response.
- Documentation quality predicts service quality. Ask to see what a service report looks like.
- Price per visit says little. Compare scope, response commitments, and who actually shows up.
- A good contractor explains root causes and tells you when not to replace something.
Verify the basics
- California contractor license: Look up the number on the Contractors State License Board (CSLB) site. Confirm it is active, the classification fits (e.g., HVAC, refrigeration, plumbing, boiler), and the bond is on file.
- Workers' compensation: Required if they have employees. The CSLB record shows the workers' comp status.
- General liability insurance: Ask for a certificate of insurance (COI) naming your company or property as additional insured when required by your lease or policy.
- Bonding: Required for licensing; larger projects may require performance and payment bonds.
- Business basics: A real address, a stable phone number, and a track record in your area.
Davinci Mechanical operates under California contractor license #1083101. You can verify any contractor, including us, on the CSLB website.
Confirm they actually do commercial work
- Do they service rooftop units, refrigeration, ice machines, and water heaters, or only residential-style systems?
- How do they handle roof access, cranes, and rigging?
- Do they have experience with your property type (restaurant, medical, retail, school)?
- Are their technicians trained in commercial refrigeration and EPA-certified for refrigerant handling?
- Can they work with your building's rules (certificates of insurance, access hours, security)?
Response, availability, and after-hours
A restaurant with a failed walk-in or a clinic with a failed medication fridge does not have until Monday. Ask what their emergency process is: who answers the phone, how quickly they dispatch, whether they carry common parts on the truck, and what after-hours costs look like. Get this in writing for plan members.
Documentation and reporting
- What does a service report look like? Ask for a sample.
- Do they record readings (pressures, temperatures, amp draws) or just 'checked unit'?
- Do they take photos?
- Is history tied to each piece of equipment, and can you access it?
- Can they produce records for health inspectors, auditors, or insurers?
This is the problem the DaVinci Portal solves: every asset has a QR tag, a service history, and photos you can pull up yourself.
Diagnostic approach
Ask how they troubleshoot. If the answer is 'we replace the likely part,' keep looking. A good contractor measures first and explains what failed, why it failed, and how they will prevent a repeat. See root-cause diagnostics.
Reading a proposal
| Look for | Why it matters |
|---|---|
| Specific equipment make, model, capacity | Allows apples-to-apples comparison |
| Scope inclusions and exclusions | Reveals what's missing from the low bid |
| Permit, crane, and disposal responsibility | Common hidden costs |
| Warranty terms (parts and labor) | Often differ between bidders |
| Payment schedule and change-order process | Controls cash flow and surprises |
| Schedule and lead times | Affects downtime |
| Refrigerant type and charge | Future service availability and compliance |
References and track record
- Ask for references from similar property types and ask how the contractor handled a problem.
- Look at reviews, but read the detailed ones. Commercial clients mention response and communication.
- For public work, ask for experience on similar agency or school projects, DIR registration, and certified payroll capability.
Red flags
- No license number on the website, vehicles, or proposals.
- Pressure to replace equipment immediately without readings or evidence.
- A quote with no scope detail or permit coverage.
- Unwillingness to provide a certificate of insurance.
- No written warranty.
- Repeated visits for the same problem with no explanation of cause.
- Cash-only or deposit demands inconsistent with the job size.
What union affiliation means for an owner
Union contractors employ workers trained through apprenticeship programs and covered by collective bargaining agreements. For owners, that typically translates to a consistent training pipeline, benefit-fund compliance, and readiness for prevailing-wage and PLA work. Davinci Mechanical is a UA Local 250 member. For private work, union status is one factor among several; for public and many institutional projects it can be a requirement.
Frequently asked questions
How do I check a contractor's license?
Search the license number on the California Contractors State License Board website and review classification, status, bond, and workers' compensation information.
Should I always take the lowest bid?
Only after confirming scope, equipment, warranty, schedule, and compliance are comparable. A low bid with missing scope often costs more later.
What should be in a maintenance agreement?
Written scope per asset, visit frequency, response targets, repair approval limits, reporting format, and renewal/termination terms.
Have a site this applies to?
Davinci Mechanical is the commercial and union division of Scottish Tom's Heating & Air. Send us the equipment list or the problem and we'll tell you what we'd check first.