Year one is a white ring under each tire. Year five is exposed aggregate you can catch a fingernail on. The salt damage timeline, and why each stage costs more to fix than the last.
The Four Litres Under Your Car
Every winter drive home ends with slush dripping off the undercarriage onto the same few square metres of slab: a concentrated chloride brine, delivered daily, all season. The Okanagan makes it worse than the coast: our freeze-thaw swings mean that brine freezes in the slab many nights and thaws by noon, and every cycle is one more round of internal pressure.
Stage One: The White Rings
The first winter leaves white crusty staining under each tire position. Most owners read it as cosmetic, and at this stage it mostly still is. The white is salt crystallizing as the brine dries, sitting in the top millimetre of paste. This is the last cheap moment in the timeline: a floor at stage one grinds clean and coats with no repair line on the quote.
Stage Two: Dusting and Soft Paste
By the second or third winter the surface starts shedding fine grit that sweeps up grey. Salt is hygroscopic: it keeps pulling moisture into the slab and holds the surface wetter for longer, and the repeated crystallization pressure begins breaking the cement paste down. The floor feels sandy underfoot, and a screwdriver dragged across the tire lanes leaves a visible scratch.
Stage Three: Pitting and Exposed Aggregate
Between years three and five the paste layer fails outright. Shallow pits appear under the tires, merge, and expose the stones of the aggregate; edges of pits keep flaking wider every season. Water now pools in the low spots and drives the cycle faster. At this stage the floor needs skim repair or full resurfacing before any coating can go down. The damage line on the quote is now real money.
What Each Stage Costs to Fix
Stage one is prevention pricing: grind and coat at the standard $5-$9 per square foot for a flake system. Stage two adds heavier grinding and spot repair, typically $1-$2 more. Stage three means cementitious skim or overlay before coating, landing at $7-$13 all-in, and badly spalled slabs beyond that head toward partial re-pour territory. The same floor, the same coating, roughly double the price for waiting four winters.
Why Coatings End the Cycle
Sealed concrete gives chloride nowhere to go. Polyaspartic and epoxy films are non-porous, so brine sits on top until it is squeegeed out the door, and the freeze-thaw pressure that breaks bare paste apart never starts. The tire lanes on a coated floor look the same in year ten as year one. A penetrating siloxane sealer is the budget alternative: it will not stop hot tire pickup or hide existing damage, but at $2-$3 per square foot it stops the chloride clock on a floor that is not ready for a full system.
Salt damage timeline on a bare Okanagan garage slab
| Winters | What you see | Fix at this stage |
|---|---|---|
| 1 | White rings under tires | Grind + coat, $5-$9/sq ft |
| 2-3 | Dusting, sandy surface, scratches easily | Heavier grind + spot repair, add $1-$2/sq ft |
| 3-5 | Pitting, exposed aggregate | Skim/overlay + coat, $7-$13/sq ft |
| 5+ | Spalling spreading beyond tire lanes | Resurface or partial re-pour before coating |
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