Holes and cracks in polished concrete: patch, fill, or leave
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Holes and cracks in polished concrete stay open unless we fill them. A polish grinds and shines the slab, and it does not put a new layer on top to cover anything. Your Slab Boss Polish quote has 2 groups for this: 1 for holes and cutouts, and 1 for cracks. Both start at “leave it as is,” which costs nothing.
Holes and cracks are different problems, so they get different choices. A hole is a gap someone made on purpose. A crack is the slab moving or shrinking on its own, and some cracks keep moving after we leave.
Holes and cutouts
Most holes in an old slab came from the last people who used the building. We find nail holes from walls that came down, anchor holes from shelves and machines, and cutouts where a pipe or a drain once came up through the floor. A small nail hole is about the size of a pencil tip. A cutout can be a foot across.
Each is a gap. Each choice below handles that gap a different way.
Why holes stay open
A polish shines the slab you have. It does not add a layer on top, so nail holes, anchor holes, and cutouts stay open.
Leave holes as they are
Free and fast.
Pro: Nothing is added to your price.
Con: Holes stay open and show, dirt collects in them, and they can catch a heel.
Patch and grind flush
We fill each hole and grind it flat.
Pro: It is quick and low cost, and the floor is flat again.
Con: The patch color will not match. Plus materials.
Match-patch attempt
We pick rock and resin to blend each patch with the floor.
Pro: It is the best look we can get.
Con: It is an attempt, not a promise. Plus materials.
Should you leave holes as they are?
This is the default, and it costs nothing. Nail holes and cutouts stay open and show. An open hole can catch a heel or a cart wheel, and dirt and water collect in it, so a shop floor full of anchor holes may be worth a patch even when looks do not matter.
What does patch and grind flush do?
We fill each hole with patch mix and grind it flat with the floor. It costs $67 per hour, counted by the crew hour, plus materials.
- Pros: It is quick and low cost. The hole is gone and the floor is flat again.
- Cons: The patch color will not match your slab. Each filled hole reads as a gray dot or a gray block on the polished floor.
What is a match-patch attempt?
We pick rock and resin to blend each patch into the floor around it, then grind and polish it with everything else. It costs $67 per hour, counted by the crew hour, plus materials.
- Pros: It is the best look we can get. On a salt-and-pepper floor, a good match-patch can be hard to find from 6 feet away.
- Cons: It is an attempt, not a promise. It takes more crew time than a plain patch, and a large cutout is harder to blend than a nail hole.
Cracks
The slab made this one. Before you pick a choice for cracks, take a close look at what kind of crack you have, because the kind decides which fix will last.
Hairline shrinkage cracks are under 1/16 inch, with no step up or down between the two sides. Every slab gives up water as it cures, and every slab shrinks doing it. These cracks are normal, and they hold still.
A crack where one side sits higher than the other is not the same. That is settling or movement. The ground under the slab is the cause, and nothing you put on top of a slab fixes what is happening under it, so a filled moving crack can open right back up. If we see one, we will tell you.
Two kinds of cracks
Every slab shrinks as it cures, so hairline cracks are normal. If one side sits higher, the ground is moving, and nothing on top fixes that.
Leave cracks as they are
Free and fast.
Pro: Nothing is added to your price.
Con: Cracks stay open and show as dark lines.
Fill cracks with resin
We fill each crack with resin and grind it flush.
Pro: It is quick and low cost, and dirt cannot sink in.
Con: The fill line shows. Plus materials.
Match-patch the cracks
We blend rock and resin to hide each crack as much as we can.
Pro: The crack is much less visible.
Con: It is not invisible, and it is not a promise. A moving crack can open again. Plus materials.
Should you leave cracks as they are?
This is the default. It costs nothing. Cracks stay open and show as dark lines in the polished floor, but on a hairline crack, many owners never notice it again after the first week.
What does a resin fill do?
We fill each crack with resin and grind it flush with the floor. It costs $67 per hour, counted by the crew hour, plus materials.
- Pros: It is quick and low cost. The crack is sealed, so dirt and spills cannot sink into it, and the edges are less likely to chip.
- Cons: The fill line shows. Resin is a solid color, so a filled crack reads as a thin line across the floor.
Can a match-patch hide a crack?
We blend rock and resin to hide each crack as much as we can, then grind and polish it with the floor. It costs $67 per hour, counted by the crew hour, plus materials.
- Pros: The crack is much less visible than a plain resin line. On a busy floor, it can almost disappear into the rock.
- Cons: It is much less visible, not invisible, and it is not a promise. A crack that keeps moving can open again and show through the blend.
These hours are not in your total
Your quote total covers the standard polish. Any choice for holes or cracks other than leaving them is billed per crew hour as worked, plus materials. Your quote lists what you picked and what you left.
What about the other defects?
Holes and cracks are 2 of the groups on your quote. Low spots, soft spots, and cut depth have their own pages. Start from the polished concrete slab defects guide to see them all, or go back to your quote to make your pick.
