Grinding & prep
Concrete Grinding & Surface Prep, Collingwood
Diamond grinding to a measured profile, with the moisture test that decides whether a coating should go down at all.
Nearly every coating failure we are called to look at is a preparation failure, not a product failure. The coating is fine. It simply never bonded to anything.
Grinding versus acid etching
A residential garage slab is usually power-trowelled, which closes and densifies the surface to a hard, almost polished skin. That skin is what a coating has to grip. Acid etching — the method in every hardware store kit — barely opens it, and it leaves salts behind that then have to be neutralised and rinsed, in a garage with no floor drain, in a region where the rinse water is going onto your driveway.
Diamond grinding removes the trowelled skin mechanically and leaves a measurable profile — the industry scale is CSP 1 through 9, and a thin polyaspartic or epoxy build wants CSP 2 to 3. You can feel it: it should have the tooth of fine sandpaper, not the smoothness of a finished floor. We grind with dust collection at the tool, so the garage does not need to be re-cleaned afterwards and the silica goes into a filter rather than into the air.
The moisture test, and why we do it before quoting
Concrete is not waterproof. A slab poured directly on grade without an intact vapour barrier will wick groundwater up and push it out of the surface as vapour, continuously. Put a sealed coating on top of that and the vapour has nowhere to go, so it collects at the bond line and lifts the coating off in sheets. It can look perfect for a year first.
This is a live issue in this area rather than a theoretical one. Older cottages and garages on the sand at Wasaga Beach, anything built close to the shoreline, and pre-1980 slabs generally are the common cases — vapour barriers under residential slabs were not standard practice for a long time. We test with calcium chloride or an in-slab relative humidity probe and we read it before quoting, because the result changes the job: a slab over the threshold needs a moisture-mitigating primer underneath the system, and that is a real line item, not an upsell.
Control joints
The saw-cut lines in your slab are there so the concrete cracks where somebody chose rather than at random. They are still moving. Filling them flush and coating straight over is the standard shortcut, and the joint reappears as a split in the coating within a couple of seasons. They get filled with a flexible polyurea and honoured, not erased.
Talk to a Collingwood floor coating contractor
Tell us the size of the bay, roughly when the slab was poured, and whether the building is heated. That is usually enough for a realistic range over the phone — and enough for us to say if you are in the small group of floors where the honest answer is to fix the water before spending anything on a coating.