Concrete coating is a low-barrier trade to get into and a high-consequence one to get wrong. A bad install doesn't show up as a problem on day one — it shows up eight months later as a peeling corner or a blistered patch, by which point the crew that installed it may not be easy to reach. Vetting a contractor before you sign is the highest-leverage thing you can do to avoid that outcome. Here is what to actually check.

ROC license and how to look one up

Arizona licenses contractors through the Registrar of Contractors (ROC), and most concrete coating work falls under that licensing requirement. Ask for the contractor's license number directly, then verify it yourself rather than taking it on faith — the ROC maintains a public license search at roc.az.gov where you can look up a contractor by name or license number and see the license classification, its current status, bond information, and any complaint or disciplinary history on file. A legitimate contractor will give you their license number without hesitation, since it's public information either way.

Insurance

A license is not the same thing as insurance. Ask specifically for proof of general liability insurance, and ask whether the crew doing the physical work is covered by workers' compensation. If a worker is injured grinding your slab and the company carries no coverage, the liability exposure can fall back on the property owner. A contractor with real insurance can produce a certificate of insurance on request — if that request gets stalled or deflected, treat it as a red flag rather than an oversight.

Prep method questions

Ask exactly what prep method is used before coating: diamond grinding or acid etching. Grinding mechanically opens the concrete's pore structure for a real bond; etching is a faster, cheaper chemical shortcut that does not profile the surface the same way and tends to produce a shorter-lived floor. Ask how they handle existing cracks, whether they test for prior coatings before grinding, and how they handle control joints. A contractor who can describe their process specifically, without hand-waving, is usually a contractor who has a real process.

Product data sheets

Ask for the technical data sheet (TDS) of the specific product being installed, not just a brand name or a generic description like "commercial-grade epoxy." A real data sheet lists cure times, dry-film thickness, abrasion resistance figures, and application conditions — information a contractor confident in their materials will hand over without friction. If a contractor cannot name the specific product line they're installing, they likely cannot speak to its actual performance either.

Moisture testing

Ask whether moisture testing is part of the standard process or an optional add-on. On a slab-on-grade — which describes nearly every residential garage in the Valley — vapor drive from the soil below can cause a coating to blister or delaminate if it isn't checked and mitigated before installation. A contractor who tests every slab as a matter of course is treating your floor's longevity as their problem to solve up front, not yours to discover later.

Warranty in writing

Get the warranty terms in writing before work begins, not promised verbally and formalized later. Ask what specifically is covered (peeling, delamination, yellowing), what voids it, how long it runs, and whether it transfers to a new homeowner if you sell. A contractor unwilling to put warranty terms in writing before the job starts is not a contractor whose verbal warranty is worth much after the job ends.

References and photos

Ask to see photos of completed work, ideally recent installs rather than a handful of flagship projects from years ago — a floor that still looks good after two or three years of real use tells you more than one photographed the day it was finished. If a company shows only day-of-completion photos and nothing older, ask directly why. References from actual customers, even a short phone call, are worth the ten minutes it takes.

Red flags

  • Pressure to sign the same day, with a "discount" that expires if you don't.
  • No license number offered without being asked twice.
  • A quote given over the phone with no inspection of the actual slab.
  • Reluctance to put the warranty terms in writing before the deposit is paid.
  • A price dramatically below every other bid with no explanation for the gap.
  • No mention of moisture testing or prep method unless you ask first.
  • Demanding full payment upfront, especially in cash.

THE CHECKLIST

Ten questions to ask before you sign anything, in the order that matters most.

The 10-question checklist

  1. What is your Arizona ROC license number, and can I verify it myself?
  2. Can you provide a current certificate of general liability insurance?
  3. Do you diamond-grind or acid-etch the slab before coating?
  4. What is the specific product line and system, and can I see the data sheet?
  5. Do you test for moisture before every install, or only on request?
  6. How do you handle existing cracks and control joints?
  7. How many coats, and what is the topcoat's dry-film thickness?
  8. What does the warranty cover, for how long, and can I have it in writing?
  9. Can I see photos of installs that are at least two or three years old?
  10. What is the payment schedule, and how much is due before work starts?

Choosing a contractor — questions

Q Is it legal for a contractor to work without an ROC license in Arizona?

Arizona requires a Registrar of Contractors license for most construction work above a small dollar threshold, and concrete coating installation typically falls under that requirement. Working with an unlicensed contractor also usually means no recourse through the ROC complaint process if something goes wrong.

Q How do I actually verify a license number, not just take their word for it?

Search the contractor's name or license number directly on the Arizona Registrar of Contractors website (roc.az.gov). The record shows the license status, classification, bond information, and any complaint history — all public information, and worth five minutes before you sign anything.

Q Should I be suspicious of a contractor who wants full payment upfront?

It's worth asking about, though it isn't automatically disqualifying — Arizona law limits how much a residential contractor can require as a deposit before work begins. A contractor asking for the full amount upfront, in cash, with no contract, is a combination worth walking away from.

Q What is the single most important question to ask before hiring?

Ask exactly what prep method they use and why — diamond grinding versus acid etching. The answer to that one question tells you more about whether a floor will last than almost anything else on this page, because prep quality is the single biggest driver of whether a coating bonds and stays bonded.