Coatings cover damage, they do not cure it
A floor coating can hide small imperfections, but it cannot fix the reasons concrete cracks, flakes or pits. Before a coating goes down, damage has to be repaired so the surface is sound and smooth, and anything that suggests a bigger problem has to be investigated. The most-viewed repair videos show how professionals and serious DIYers handle common damage. This post explains what can be repaired, how, and when a slab needs more than a coating.
Hairline cracks
Hairline cracks are common in garage slabs. Tim Seay, in a video with more than 1.3 million views, patches hairline cracks before the first coat on every floor. Mike Day fixes cracks with a patch repair material and grinds the patches smooth before cleaning.
Wider cracks: penetrating epoxy fill
Concrete Floor Solutions, in a video with more than 160,000 views, shows a floor with cracks all over it. After grinding to expose and clean them, the crew fills them with a low-viscosity, rapid-setting epoxy designed to penetrate to the bottom of the crack and glue it back together. The presenter says reaching the bottom of the crack is what keeps it from coming back.
Very wide cracks: pre-fill with sand
For the widest cracks, Concrete Floor Solutions first fills them partway with fine sand so the thin epoxy does not run out the bottom. The epoxy then soaks through the sand. The crew deliberately overfills every crack.
Grind repairs flush
Overfilled repairs are then ground smooth by hand. The presenter explains that coatings do not stick well to the shiny surface of cured repair material, so grinding both levels and roughens it before the primer.
Working time matters
The rapid-set epoxy in that video gives roughly 45 seconds of working time once mixed, and the presenter points out that material in bulk heats up and sets faster. Repair products have short pot lives, so mix only what you can place quickly.
Large cracks and spalls: cementitious repair
Shopfix, in a video with more than 180,000 views, cleans cracks with a vacuum and a pressure washer with a narrow nozzle, degreases, removes standing water, and fills large cracks about half an inch or wider with a concrete resurfacer mixed to a trowel consistency. After curing, high spots are scraped off and the floor is cleaned again.
Pitting: resurfacing
Shopfix attributes heavy surface pitting in its garage to salt deposits. After applying a concrete primer, the crew pours a self-leveling resurfacer mixed to a thin consistency over the floor. Weighing the powder and measuring water consistently helps each batch mix the same.
Control joints
Control joints are cut on purpose to guide cracking. Whether they are filled or left open under the coating is a design decision. Ask your installer how joints will be treated and whether movement is expected.
When damage signals a bigger problem
Some damage points to causes a coating cannot fix. Cracks that keep widening, sections of slab that move up or down, or areas that are always damp need investigation first. Surface IT 805, in a video with more than 100,000 views, traced blisters in a coating to irrigation water and an exterior slab sloped toward the house; the outside water problem had to be fixed before the floor could be redone.
Signs to look for
Look for cracks with one side higher than the other, crumbling edges that keep spreading, dark damp areas, and white powder on the surface. Note them before the estimate.
Who should handle structural concerns
If cracks are wide, active or offset, a coating contractor is not the right person to judge structural safety. A qualified engineer or foundation professional should assess them.
FAQ: Will repaired cracks show through?
Fine lines may be faintly visible in solid colors. Flake floors hide them well.
FAQ: Can new cracks appear after coating?
Yes. If the slab moves, the coating can crack with it. Repairs address existing damage, not future movement.
Why repair before grinding the whole floor?
Concrete Floor Solutions grinds first to open and expose all cracks, fills them, then grinds the repairs again. Shopfix cleans and repairs first, then prepares the surface. Either order works if the repairs end up flush and roughened before priming. Ask your installer which sequence they use and why.
Outgassing from repairs and pores
Repairs and open pores can release air under a fresh coat, causing pinholes. Leggari Products describes a thin first coat that seals the pores to minimize outgassing bubbles before the decorative coat goes on. LearnCoatings likewise notes that primers seal the surface to help prevent bubbles in later coats.
Repair materials compared
Low-viscosity epoxy suits narrow cracks because it penetrates. Cementitious resurfacers suit large voids and widespread pitting. Flexible joint fillers suit joints where some movement is expected. Using the wrong material for the damage can cause the repair to crack or shrink under the coating.
What to expect on your quote
A quote should state the repair method, the material and how much repair is included. Our page on crack and joint scope in a floor proposal explains what to look for.
Get your slab assessed
Austin Epoxy Flooring Pro inspects and repairs slabs before coating in Austin and Georgetown. Call (512) 325-5434, open 24 hours, 7 days a week.
Related pages
Related pages on our site: Crack and joint scope in a floor proposal; How to prepare a garage floor for epoxy; Leveling substrates before high-gloss epoxy; Concrete moisture questions for your estimate; Commercial epoxy joint preparation.
Call 512-325-5434 (open 24 hours, 7 days a week) or request a free estimate.
Sources
How to repair cracks and spalls in concrete floors before applying epoxy coatings. — Concrete Floor Solutions Inc. (YouTube, 161,759 views as reported 2026-10-14)
How to Repair and Prep Concrete Before Epoxy - Watch Before Applying Epoxy Coatings! — Shopfix (YouTube, 180,770 views as reported 2026-10-14)
How To Epoxy Coat Your Garage Floor | Must Watch For Diy'rs — Mike Day Concrete (Everything About Concrete) (YouTube, 1,892,569 views as reported 2026-10-14)
Epoxy, Polyurea or Polyaspartic : Which is the BEST garage floor coating? — Tim Seay (@TimDCVA) (YouTube, 1,367,340 views as reported 2026-10-14)
Epoxy Floor Failure/ Moisture Remediation/How To Fix/Moisture Barriers/ #surfaceit#surfaceit805 — Surface IT 805 (YouTube, 100,839 views as reported 2026-10-14)
Epoxy Floor Peeling? Here are the Reasons (and how to prevent it) — LearnCoatings - Epoxy Flooring Training (YouTube, 77,791 views as reported 2026-10-14)
A CONTRACTOR TELLS ALL! - EPOXY FLOORS FOR BEGINNERS — Leggari Products (YouTube, 1,554,858 views as reported 2026-10-14)