Problem
Garage floor cracks
Most cracks are cosmetic. A few are structural. The coating choice depends on which yours is.
Diagnostic indicators
How to recognise this on your floor.
None of these are diagnostic on their own. Two or three together usually means we are looking at the same thing.
Hairline cracks that wander
Hairline cracks that wander across the slab in no particular direction
Straight saw-cut control joints
Straight saw-cut control joints (these are by design, not damage)
Cracks that run wall-to-wall
Cracks that run wall-to-wall in a roughly straight line
Cracks where one side
Cracks where one side has lifted higher than the other
Cracks that open and
Cracks that open and close with the seasons
Cracks that have been
Cracks that have been filled before but keep reopening
Plain English
What is going on.
Every concrete slab cracks. The question is whether your crack is shrinkage from the cure, settlement under the slab, or active structural movement. Each one wants a different repair, and applying the wrong one locks in a future failure.
Hairline shrinkage cracks under a millimetre wide are normal and do not need engineering. They get a flexible filler and a coating runs over the top. Settlement cracks where a soft spot under the slab has compressed need the void addressed before any cosmetic fix. Working cracks that move with seasonal load need an isolation joint engineered into the new coating, or they will telegraph through every system you put down.
We assess on site, classify the crack, and write a repair specification before we pour anything new on top.
Engineering cause
Why concrete cracks
Three structural mechanisms. Drying shrinkage as the wet concrete cures and loses water; this is unavoidable and produces the fine random cracks most slabs have. Differential settlement when the ground under one part of the slab is softer than another; this causes one side to drop. And applied load that exceeds the slab's tensile capacity, often near doorways, posts, or vehicle paths.
The first is cosmetic and almost always coatable. The second and third are conversations about what is happening below the slab, not on top of it.
The path
What we do about it
Recommended path: Tier 3 Expert assessment
A Tier 3 Expert visit measures every visible crack, photographs it, and classifies the mechanism. The report names which cracks are cosmetic, which are settlement, and which are working. For each, the report specifies a repair: flexible filler, structural epoxy injection, or an isolation joint cut into the new coating system.
Once the repairs are scheduled, the floor finish runs over the top. We do not coat first and patch later; the order matters because some fillers and the topcoat need to cure together for the joint to read as one surface.
Brief Bill
Send the brief, we will read the slab.
Tier 3 Expert engagement. Fee is $900 and credits against the eventual remedial contract. One business-day reply from Bill.
Common questions
Before you ask, this is what most people want to know.
Almost never. Most garage slab cracks are cosmetic. The ones that matter for safety are obvious: a wall-to-wall straight line with vertical displacement, or a crack that gets visibly wider in dry weather. The Tier 3 visit will say which type yours is.
Not if you want a finish that lasts. Coatings track every crack underneath them. If a crack moves and the coating cannot, it telegraphs through. We address the crack first and tune the coating to whatever movement is left.
Cosmetic shrinkage cracks, repaired and coated properly, do not come back through the new coating. Working cracks managed with an isolation joint stay invisible because the joint absorbs the movement. Settlement that has not been addressed structurally will keep moving and we will tell you that before we coat.
Cosmetic filler work is included in most strip and recoat scopes. Structural epoxy injection sits between $80 and $200 per linear metre depending on access. Isolation joints add 5 to 10 percent to the coating contract. We price all three on the report.
No. Saw-cut control joints are designed to crack on purpose, so the rest of the slab does not crack randomly. They get a flexible filler and the coating respects the joint line. They are not damage.
If the cracks are clearly cosmetic and the slab is otherwise sound, yes. If there is any sign of settlement or working movement, the Tier 3 protects you from a coating contract that cannot deliver. The $900 fee credits against the eventual remediation.
Ready when you are
Most rescues end on a properly engineered garage finish.
Three finish tiers, prices on the page, fixed before we start.