Salt, Cold, and Your Garage Concrete

Two years ago, I saw a completely spalled concrete slab in a Brossard garage. The owner had bought it that way — the house was 12 years old — and he thought it was normal. It's not normal. That's what road salt does to unprotected concrete after a dozen Quebec winters.

What Salt Actually Does to Your Concrete

Concrete is porous. Not in an obvious way, but enough to absorb the salt water your tires track in from the street every winter. Once inside, that water freezes. When water freezes, it expands by about 9% in volume. That creates microcracks. The following spring, water enters those microcracks and starts the cycle again. After 10 or 15 years, you have a slab that's spalling.

A properly applied epoxy coating creates an impermeable membrane over the slab. Salt water can no longer penetrate. Freeze-thaw cycles have nothing to grip.

It's Not Just About Appearance

I understand that many people see epoxy as something decorative — a beautiful, shiny floor for a nice garage. That's true, it does look great. But the main reason we recommend it on the South Shore is protection. A concrete slab that starts spalling doesn't stabilize on its own. It gets worse. And replacing a concrete slab costs far more than protecting it in the first place. (I don't know why people often wait until the problem is visible before acting, but that's what I regularly observe.)

Not All Epoxies Are Equal

I'll be straightforward about this: the kits you find at big-box renovation stores don't hold up. Not in our climate. Professional 100% solids systems are engineered to withstand extreme thermal shock — from -30°C to +35°C — and chemicals like motor oil and antifreeze. Consumer kits are not.

Tip: if a contractor offers a very low price and doesn't mention mechanical concrete preparation, that's a red flag. Prep is where the serious work happens.

In Summary

Protecting your garage concrete on the South Shore is a practical decision, not just an aesthetic one. Salt and cold do their work every winter. A good epoxy coating does its work in return.