Most commercial floor failures are not product failures. They are hiring failures. The coating on the datasheet was capable of doing the job; the crew that installed it skipped a step you were never in a position to see, and the floor came apart eighteen months later while everyone pointed at everyone else.
That is the uncomfortable part of buying flooring: almost all of the quality is buried under the finished surface. Surface preparation, moisture testing, primer selection, mil thickness, and cure conditions are invisible the moment the floor is done. By the time the evidence surfaces, the crew is gone and the warranty conversation has become a negotiation.
The defense is not a better product. It is better questions, asked before you sign, with the answers in writing. What follows are twelve of them, plus what a good answer sounds like and what should make you walk. A competent contractor will not be annoyed by any of this. We field these questions regularly, and the ones who ask them are consistently the easiest clients to work with, because the scope is understood on both sides before anyone mobilizes.
Why the usual vetting checklist is not enough
Insurance certificates, a business license, and a portfolio of pretty photos are table stakes. They tell you a company exists and owns a camera. They tell you nothing about whether the crew that shows up at your building knows what a CSP-3 profile looks like or what to do when the calcium chloride test comes back high.
The questions that matter are technical and procedural. They are about process, documentation, and who physically does the work. Ask them in a walkthrough, not over email, and pay as much attention to how fast and specifically someone answers as to what they say.
The 12 questions
1. Who is actually performing the work — your employees or a subcontractor?
This is the first question because it determines the value of every answer after it. If the company you are contracting with subcontracts the installation, then the training, the quality standards, and the accountability all belong to a company you never interviewed.
Good answer: “Our own crews, and they self-perform every step — prep, primer, base, topcoat.” Red flag: vagueness, “we have a network of installers,” or an inability to tell you who will be on site.
2. How will you prepare the surface, and what profile does this system require?
Surface prep is where floors are won or lost. You want to hear a specific mechanical method — diamond grinding or shot blasting — tied to a specific target profile, usually expressed as a CSP number from the ICRI concrete surface profile scale.
Good answer: “Shot blast to CSP 3 through the open areas, diamond grind the perimeter and around equipment where the blaster can’t reach, and detail the coving areas by hand.” Red flag: acid etching, pressure washing, or “we’ll clean it and prime it.” Acid etching does not produce a reliable profile on a dense industrial slab, and it introduces moisture. If you want the reasoning behind method selection, our comparison of diamond grinding versus shot blasting lays out when each is appropriate.
3. Will you test the slab for moisture, and which test?
Moisture vapor emission is the leading cause of delamination in coated concrete, and it is invisible. Slabs on grade without an intact vapor barrier, slabs below grade, and slabs in buildings with a high water table all deserve testing.
Good answer: a named standard — calcium chloride testing per ASTM F1869 for MVER, or in-situ relative humidity probes per ASTM F2170 — plus what the contractor will do if the numbers come back high (moisture-mitigating primer, a different system, or a documented change order).
Red flag: “We’ve never had a problem” or an offer to skip testing to save money. If you decline testing, expect the warranty to exclude moisture-related failure — which is exactly how owners end up with no coverage. This is covered in more depth in our explainer on what epoxy floor warranties actually cover.
4. What is the specified system, layer by layer, with mil thickness?
“Epoxy floor” is not a specification. You want primer, base coat, broadcast media if any, and topcoat, each named, each with a target dry film thickness and a coverage rate.
Thickness is where quotes quietly diverge. Two bids can both say “epoxy” while one is a 12-mil roller coat and the other is a 1/8-inch broadcast system — a difference in material volume of roughly ten times. Whether you need National Armour 100, a higher-build ArmourPro 120, or a urethane topcoat like NationalSeal Urethane High-Gloss 210 depends on your traffic and chemistry, not on what is cheapest to bid.
5. Who manufactures the material, and can I see the technical data sheets?
You want a named manufacturer and real TDS and SDS documents, not a private-label bucket with no chemistry behind it. The data sheet tells you cure schedule, chemical resistance, recoat window, and required substrate conditions — all of which become the terms of your warranty later.
Red flag: refusal to identify the manufacturer, or datasheets that cannot be produced on request.
6. How will you handle cracks, joints, spalls, and existing coatings?
Remediation is the most common source of change orders. Ask what the bid assumes and what it excludes. Moving joints must be honored or the coating will crack over them; static cracks get routed and filled; spalled areas get patched with a compatible repair mortar; existing coatings must be removed or tested for bond.
Good answer: a defined allowance with a unit price for anything beyond it. Red flag: silence on the subject, which usually means a change order is coming.
7. What are the temperature, humidity, and dew point requirements — and how will you meet them?
Resinous systems cure chemically and are sensitive to conditions. Applying near or below the dew point causes amine blush and adhesion problems; cold slabs slow cure and change viscosity; excessive heat shortens pot life. In an unheated Chicagoland warehouse in February, this is a real scheduling constraint, not a formality.
Good answer: the contractor will measure slab temperature and dew point on the day and has a plan — temporary heat, dehumidification, or rescheduling. Red flag: “we install year round, no issues.”
8. What is the phasing plan, and how long until I can walk on it and drive on it?
Foot traffic return and full chemical or vehicular service are different milestones, often separated by several days. Get both, in writing, for the system being installed. Then get the phasing: which bays, which shifts, how containment and traffic control work while adjacent areas stay live.
This is also where you find out whether the bid you are holding assumes an empty building. Two quotes with different phasing assumptions are not comparable, which is one of the traps discussed in reading a flooring quote and what belongs in the scope of work.
9. What warranties are offered, and who backs each one?
There are two, and they are separate: a material warranty from the manufacturer and a workmanship warranty from the installer. Ask for both in writing, with the term, what is covered, what is excluded, and the claim procedure. Ask specifically what voids them.
Red flag: a verbal warranty, or a written one you only receive after final payment.
10. Have you done this specific environment before?
Not “commercial flooring” — your environment. A wash-down meat processing room, a hospital operating suite, a battery charging area, and an aircraft hangar have almost nothing in common except the word “concrete.” Ask what changes in the spec because of your process: thermal shock, chemical exposure, static control, slip resistance, USDA or FDA expectations, drain slope, coving.
A contractor who works regularly in food and beverage plants or healthcare facilities will answer this with specifics about drains, coving heights, and cleaning chemistry. Someone who only does garage floors will answer in generalities.
11. How do you verify thickness and coverage on site?
This separates crews that hit spec from crews that hope. Real answers include tracking material consumption against the calculated coverage rate for the square footage, wet film thickness gauges during application, and documenting it. If the bid calls for 125 square feet per gallon and the crew is getting 200, you are getting roughly 60 percent of the specified thickness — and no one will ever know unless someone is counting buckets.
12. What documentation will I receive at closeout?
Ask for a closeout package: moisture test results with dates, prep method and achieved profile, product batch numbers, application dates and ambient conditions, coverage records, and both warranty documents. This is your evidence file. If the floor ever fails, it is the difference between a warranty claim and an argument.
Red flags that should end the conversation
- A per-square-foot price given without seeing the slab. Nobody can scope prep from a phone call.
- Large deposits demanded up front, particularly above the cost of materials.
- Pressure to decide today or a discount that expires in 48 hours. Commercial flooring is not sold that way.
- No written scope — a one-line proposal with a number on it.
- Reluctance to discuss moisture testing or an assurance that it is unnecessary without any evidence.
- Acid etching proposed as surface prep on an industrial slab.
- Unwillingness to name the manufacturer or provide data sheets.
- Cannot describe the crew. If nobody can tell you who is showing up, nobody is accountable for what they do.
How to compare the answers you get
Build a simple matrix. Rows are the twelve questions; columns are the bidders. Score each answer as specific, vague, or evasive. You will find the pricing spread suddenly makes sense — the low bid is usually low because two or three rows are blank.
| Area | What a strong answer contains | What to watch for |
|---|---|---|
| Surface prep | Named mechanical method plus target CSP | Acid etch, “clean and prime,” no profile named |
| Moisture | Named ASTM test and a plan if results are high | Testing treated as optional or unnecessary |
| System spec | Layer-by-layer with mil thickness and coverage | “Epoxy floor” with no build described |
| Crew | Self-performed by employees | Unnamed subcontractors or an installer “network” |
| Schedule | Phasing, foot traffic and full service return times | Single lump duration, no phasing detail |
| Warranty | Separate material and workmanship terms in writing | Verbal assurances, documents after payment |
| Closeout | Test results, batch numbers, conditions, coverage log | No documentation offered |
What references are actually worth asking
Reference-checking is only useful if you ask the right thing. “Were you happy with the floor?” gets you a yes from everyone. Instead ask:
- How old is the floor now, and what does it look like in the highest-traffic zone?
- Did the schedule hold, and were you able to operate around the work?
- Were there change orders, and were they explained before the work happened?
- Have you had any repairs, and how did the contractor respond?
- Would you use the same system again for the same space?
Ask for a reference in an environment like yours, and if it is nearby, go look at the floor. A five-year-old floor in a live building tells you more than any photo gallery. Contractors who work across the region should be able to point you to something reasonably close, whether you are in Chicago, Naperville, or Elk Grove Village.
What happens on a properly run job
For context on what you are buying, it helps to know the sequence: walk and assess the slab, test for moisture, mechanically prep to profile, vacuum and detail, repair cracks and spalls, prime, install the base build, broadcast and topcoat, then cure to spec before returning traffic. Our overview of the commercial epoxy installation process covers each stage and why the order matters. If a contractor’s description of the job leaves out steps, that is worth asking about directly.
Frequently Asked Questions
Is the lowest bid always a bad idea?
Not necessarily, but it is always worth explaining. A lower number is legitimate if the contractor self-performs, has efficient crews, and is not paying a general contractor’s markup. It is a problem when the number is low because prep, moisture testing, or thickness were reduced. Ask the low bidder to walk you through exactly where their savings come from.
How many quotes should I get?
Three is usually enough to see the spread, provided all three are bidding the same scope. More than that tends to add noise rather than information. Insist that everyone bids the same prep standard and the same phasing plan, or you are comparing different projects.
Should I hire through my general contractor or direct?
Both work. Direct hiring gives you a clearer line of accountability and usually avoids a markup layer; going through a GC can simplify coordination on a larger project. Either way, ask the twelve questions of whoever is physically installing the floor, not just of the entity signing the contract.
What if a contractor gets defensive about these questions?
Take it as information. A crew that installs to spec has nothing to lose by describing the spec. In our experience the questions tend to speed up a project, because both sides agree on the scope before mobilization instead of arguing about it during.
Do I need to be present during the work?
You do not need to supervise, but someone from your team should see the slab after prep and before priming. That is the one moment when the most important part of the job is visible. Take photos. It costs you fifteen minutes and it is the best documentation you will ever have.
How do I know if my building even needs a coating?
Sometimes it does not. Dry warehouses with sound slabs are often better served by polishing, and a good contractor will say so. Our comparison of epoxy versus polished concrete versus tile on lifetime cost walks through where each option makes sense.
Ask us all twelve
National Epoxy has installed commercial and industrial floors across Chicagoland, Northwest Indiana, and Southeast Wisconsin for over 30 years. Our crews self-perform every step — prep through topcoat — and we would rather answer these questions in a walkthrough than defend a floor later.
Bring your slab, your process, and your shutdown window. We will tell you what the floor needs, what it does not need, and where a different approach would serve you better. Start on the contact page or call (630) 919-5000.