Diamond grinding: the non-negotiable first step
Concrete leaves the forms with a weak, smooth surface layer that coatings can't grip. Professional prep removes it mechanically — a planetary diamond grinder scours the slab to a consistent profile, stripping old paint, sealers, tire shine buildup, and the remnants of failed kits along the way. It's loud, it's dusty (good crews run industrial vacuums on the grinder), and it's the single biggest difference between a coating that bonds for a decade and one that sheets off at the tire lines. If a quote says "acid etch" or "power wash and coat," you have found the shortcut that causes most failures.
Cracks, spalls, and joints
- Cracks are chased open with a V-groove, filled with a flexible or rigid repair compound suited to whether the crack is still moving, and ground flush. Hairlines get the same respect as wide ones — uncoated cracks telegraph through any finish.
- Spalls and pitting — the chipped, cratered patches from years of dropped tools, road salt tracked in from Sierra trips, and freeze-thaw at foothill elevations — are patched and leveled so the finished floor reads as one surface.
- Control joints are a judgment call your installer will walk through with you: fill them flush for a seamless look, or honor them so the slab can keep moving. Both are legitimate; hiding the conversation is not.
Moisture: the silent failure
Concrete wicks ground moisture upward, and vapor pressure under an impermeable coating will blister and delaminate it — sometimes in the first wet winter. Pros test before they quote: a calcium-chloride or in-situ probe reading tells them whether your slab needs a moisture-mitigating primer. This matters doubly in our older neighborhoods and low-lying areas near the rivers and creeks, where slabs were poured without modern vapor barriers. A quote that never mentions moisture is a quote written by hope.
Rescuing a failed floor
Peeling DIY kit? Flaking builder paint? A previous coating letting go in sheets? The rescue is mechanical, not chemical: the failed material is ground off back to sound concrete, the damage it was hiding gets repaired properly, and a real system goes down on a slab that's finally ready. It's the one project type where skipping steps has already been tried — by the last floor.
Related pages
All floor coating services · Epoxy vs. polyaspartic vs. DIY · What a coating costs · Commercial floors
Not sure what shape your slab is in?
That's the normal starting point. Describe the floor honestly on the form — cracks, stains, old paint, all of it — and your matched pro will assess it in person before quoting.
Educational note: any cost ranges mentioned on this site are typical, general information only. Your installer confirms an exact quote directly with you before work begins.