Quick answer: the warning signs of a bad epoxy floor job are visible in the first hour after the crew leaves. Look for roller lap lines, widespread pinholes, fisheye craters, thin or ragged edges at the walls and the garage door, control joints that were coated straight across, and a gallon count that does not match the thickness you were quoted. Check them under a low-angle work light, write them down with photos, and send the list in writing before you pay the final invoice.
A finished epoxy floor looks good from the doorway at noon, which is why so many poor installs get signed off. The defects that matter show up in raking light, at the edges, and in the paperwork. If you are still deciding who should install your floor, our epoxy garage floor installation in Denver page explains how we prep, coat and warranty a garage, and the checklist below works as a yardstick for any contractor, including us.
Before the Crew Leaves: The Eight Things to Look At Under a Work Light
Do the walk-through while the installer is still on site, with the garage door closed and a bright LED work light held low, close to the floor and aimed across the surface instead of down at it. Raking light exaggerates every ridge and crater, which is exactly what you want. Eight checks cover most of what goes wrong.
| Check | What Good Looks Like | What a Defect Tells You |
|---|---|---|
| Roller lap lines | Uniform sheen, no visible overlaps | Sections were too large or the edge set before the next pass |
| Pinholes | None, or a very few in a small area | Air escaped the slab through wet coating, or the primer was skipped |
| Fisheyes | No round craters | Oil, silicone or sealer was left on the slab |
| Flake coverage | Even broadcast, no bare patches | Rushed broadcast or too little base coat to hold the flake |
| Edges and walls | Clean, straight line at the wall and door | Edges were not cut in or taped, or the coating is thin there |
| Control joints | Cleaned out, filled with flexible sealant | Coated over, so the next slab movement will tear the film |
| Texture | Consistent, as agreed for slip resistance | Aggregate was unevenly broadcast or clumped |
| Cleanliness | No dust, hair or debris locked in the film | The space was not swept and tacked before the topcoat |
Take a photo of each problem with something for scale beside it, such as a coin or a tape measure, and note the location in the garage. A defect you can point to on a dated photo is far easier to resolve than one you remember.
Roller Lap Lines, Pinholes and Fisheyes, and What Each One Tells You
Each of these three defects points to a different mistake, and knowing which one you are looking at tells you whether the fix is a polish or a redo.
Roller lap lines are bands where one roller pass overlapped a pass that had already started to set. They show as a slightly different sheen in a straight line. Epoxy and polyaspartic coatings have a limited working time, and Denver's dry air and strong sun can shorten it in a garage with the door open. A crew that works sections too large for the conditions leaves laps behind. In a garage this is mostly cosmetic, but it is a dependable sign of rushed application.
Pinholes are tiny holes where air rising out of the concrete broke through the wet coating. Concrete is porous and warms during the day, so air in the pores expands and rises. A properly primed slab, coated while the temperature is steady or falling, resists this. A handful of pinholes is cosmetic. Widespread pinholing means the slab was not sealed or the coating went on too fast, and it leaves the surface open to oil and tire staining.
Fisheyes are round, crater-like voids where the coating pulled away from a spot of contamination, usually oil, silicone or a leftover sealer. They are a prep failure, not an application failure. A single fisheye can be spot repaired. A scattering of them across the floor means contamination was never fully removed, and the coating around them may not be bonded either, which is where the peeling later begins. Our guide to the four causes of epoxy floor peeling covers how contamination turns into lifting, and how to test for it.
Edges, Terminations and the Line Where the Coating Meets the Door
Edges fail first, so inspect them last and most carefully. A good install terminates the coating in a clean, straight line along the wall, around posts and drains, and at the garage door threshold. The coating at the edge should be the same thickness as in the field, with flake carried right up to the line.
Look at the threshold in particular. This is where tires, water and road salt do their work, and where a thin or feathered edge lifts. Run a fingernail along the coating at the door line. It should feel solid and bonded, not like a skin that catches and lifts. At walls, check that the coating is not smeared up the drywall or baseboard and that the cove or cut line is straight. Ragged edges are a good indicator of how much care the rest of the job received, because they are the part of the work that is easiest to rush and hardest to hide.
Also look at the transition between the coated floor and any uncoated concrete, such as a step or an adjoining room. The edge there should be intentional and finished, not a place where the coating simply stops.
Control Joints That Were Coated Over Instead of Honored
A control joint is a cut in the slab placed so that the concrete cracks in a straight line where you want it to, instead of wandering across the floor. It is supposed to move. Epoxy is rigid and does not stretch, so a coating that bridges the joint will tear the next time the slab shifts, and the crack will telegraph through the finish along the joint line.
The correct treatment is to clean the joint out, install a backer where the joint is deep, and fill it with a flexible polyurethane or polyurea joint sealant, then coat up to the joint edges so the line stays visible. Walk the floor and find the joints, which in a typical garage form a grid of long straight lines. If the coating runs unbroken across them and you cannot see a defined joint line, they were covered. Expect hairline cracks along those lines within a season or two, especially after a Colorado winter of freeze and thaw cycles.
Existing cracks matter too. A crack that was visible before the job should have been routed or ground and filled, not painted over. If you can still see the old crack tracing through a new floor, the repair was skipped. For floors that need joints or cracks reworked, see our epoxy floor repair in Denver service.
Checking Actual Coverage Against the Mil Thickness You Paid For
You cannot measure the thickness of a finished floor with a ruler, but you can check the arithmetic. A coating's data sheet states a spread rate in square feet per gallon, and the thickness it produces follows from it. The conversion for a 100 percent solids product is simple: 1,604 divided by the spread rate in square feet per gallon gives the dry thickness in mils.
Here is how that works on a two-car garage of about 500 square feet. A quote that promises roughly 15 mils of base coat at 100 percent solids works out to about 107 square feet per gallon, so the job needs close to 5 gallons of base coat. If the crew opened two gallons, the floor received about 6 mils. The numbers will not be exact, because some material is lost to the roller, the bucket and the slab's porosity, but a result that is half of what was quoted is not a rounding error.
Ask what was used by asking to see the empty containers, or for the material list and batch labels. A contractor who did the work properly will show you without hesitation. For the full method, with a worked check on a commercial quote, read our guide to how thick an epoxy floor should be, and for reading the product data sheet itself, see how to tell if a contractor is using quality materials.
When a Dispute Needs a Measurement
If you and the installer disagree and the paperwork does not settle it, there are standard tests. ASTM D4541 measures the pull-off strength of a coating by gluing a small dolly to the surface and pulling it off, which shows whether the coating is truly bonded to the slab. ASTM F2170 measures relative humidity inside the concrete, and ASTM F1869 measures moisture vapor emission, which together show whether moisture was a factor in a failure. Concrete surface profile, rated on the ICRI CSP scale, describes how rough the slab was ground before coating. These tests are usually done by a third party, and the results are only useful if the original specification named the standard to be met.
What to Put in Writing, and the Difference Between a Punch List and a Warranty Claim
The two documents serve different purposes, and mixing them up is how owners lose leverage. A punch list is a dated list of visible defects against the agreed specification, delivered at handover or within days. It asks the installer to finish the work as contracted. A warranty claim comes later, after the floor has been in service, and addresses failures such as peeling or delamination that appear over time. A warranty claim turns on what was specified and what the warranty covers, so the punch list and the original paperwork matter to both.
Before you pay the final invoice, do these five things:
- Photograph every defect in raking light, with a coin or tape for scale, and note the location.
- Write a dated punch list that refers to the quoted specification: product, number of coats, thickness and finish.
- Send it by email or text so there is a record, and request a date for the corrections.
- Keep the quote, the product data sheets, the warranty document and the material list together in one folder.
- Hold the final payment, within what your contract allows, until the punch list is closed.
Most reputable installers will correct a legitimate list without argument, because their reputation depends on it. Part of avoiding a bad job is choosing carefully in the first place. Our guide to how to choose an epoxy flooring contractor in Denver covers crews, subcontractors and red flags in quotes, and the 15 questions to ask before you hire give you the specific wording to use. If you are checking a DIY or kit-based job instead, the common garage floor mistakes explains which prep errors cause the earliest failures.
What Shows Up in the First 30 Days
Some problems are not visible on handover day. Watch the floor closely over the first month, because early failures point back to the install and not to wear.
| What You See | When It Appears | Most Likely Cause |
|---|---|---|
| Lifting at the garage door line | First days to weeks | Thin edge, poor profile or moisture at the threshold |
| Tire marks that stay or pull the coating | First weeks of driving | Insufficient cure time before parking, or a weak topcoat |
| Blisters or bubbles | Days to weeks | Moisture vapor or trapped air under the coating |
| Sticky or soft areas | Within days | Incorrect mix ratio or an incomplete cure |
| Cloudy or milky patches | Within days | Moisture contamination during cure |
| New hairline cracks along a line | First winter | Control joints or cracks coated over |
If a section is soft, tacky or marked by a heavy object well past the stated cure time, it was probably mixed or cured incorrectly, and that is usually a redo of that area, not a touch-up. Do not wait to raise it. A defect reported in the first weeks, with photographs and a written specification behind it, is far easier to resolve than one reported after a year of use.
Denver Conditions That Make Poor Work Show Faster
Colorado's climate is hard on coatings that were not installed well. Slabs can run cold in the mornings and warm quickly in the afternoon sun, which encourages pinholes if the coating goes on during rising temperatures. Winter road salt and magnesium chloride sit on tire treads and drip onto the floor, and freeze-thaw cycles move slabs and open joints. An installer who ignores these conditions will see problems appear sooner here than elsewhere. A good one plans the coating window around the slab temperature and dew point, and builds a floor that can take a winter of salt.
None of this means a defect is automatically a catastrophe. Many cosmetic issues are fixed with a recoat or a spot repair. The goal of the inspection is to separate the small things from the structural ones, document both, and get the work corrected under the terms you agreed to.
Frequently Asked Questions
Pinholes are tiny holes left when air escaping the concrete breaks through the wet coating. A handful in a garage is cosmetic. Widespread pinholing means the slab was not primed or the coating went on too fast, and it leaves the surface open to staining.
Work it back from coverage. Divide the gallons used by the floor area and compare it with the product data sheet's spread rate. If a quote says twelve mils and the crew used half the material that thickness requires, the floor is thinner than specified.
No. A control joint exists so the slab can crack in a straight line where you want it. Coating straight across it means the next movement tears the coating. Joints get cleaned out and filled with a flexible sealant, then the joint line stays visible.
Visible lap lines mean the installer let an edge set before rolling into it. In a garage it is cosmetic but it is also a reliable sign of rushed application or a crew working sections that were too large for the conditions.
Photograph everything in raking light before you sign anything, write a dated punch list referencing the quoted specification, and send it in writing. Keep the quote, the product data sheets and any warranty document together, because a claim turns on what was specified.