Most epoxy floors that fail in Calgary garages were doomed before the coating went on. Freeze-thaw cycles, road salt, and slab moisture are harsh - but they only destroy floors that were not prepared for them.
Calgary's climate creates a thermal cycle that is uniquely brutal for floor coatings. Every time the temperature crosses zero degrees - which happens dozens of times between October and April - moisture trapped in and around the concrete slab expands and contracts. Water expands roughly 9 percent by volume when it freezes. If an epoxy coating has even a small weak point in its bond to the concrete, that repeated expansion and contraction will find it and exploit it. A bubble forms. That bubble fills with moisture on the next thaw cycle. The next freeze expands that moisture, making the delaminated area larger. Over a single winter, what started as a pinhead-sized defect becomes a palm-sized blister that you can press down with your finger and feel the coating flex. Most homeowners first notice these in spring, when the garage warms up and the bubbles become more visible. By then, the damage is usually beyond a spot repair.
Salt is hygroscopic, meaning it actively pulls moisture toward itself. When salt-laden melt water gets tracked into a garage on your tires and boot treads, it does not just sit on the floor surface. It works into any micro-crack, pinhole, or surface imperfection in the concrete and actively draws more moisture up from the slab below. If there is a coating on top, that moisture gets trapped between the coating and the concrete. In Calgary, the combination is especially aggressive because we use a mix of road salt and calcium chloride on our roads, which is even more hygroscopic than sodium chloride alone. A single car tracked into a garage after a drive through salted roads deposits enough salt solution to create a moisture pocket under a weak coating bond within days. Over a full winter of daily parking, the cumulative salt loading on a garage floor is substantial.
Every concrete slab releases air through its pores. This is normal. But the timing of that air movement matters enormously for coating adhesion. When the temperature of the concrete is rising - as it does every morning when the sun hits the garage door, or when a Calgary chinook rolls through and warms the air by 20 degrees in an hour - the air trapped in the concrete pores expands and pushes outward through the surface. If you apply wet epoxy while the slab temperature is climbing, that escaping air passes through the uncured coating before it hardens. The result is pinholes, craters, and micro-voids throughout the coating layer. Those defects are cosmetic problems on day one. They become structural problems over the first winter, because every pinhole is an entry point for moisture and salt. A floor with 50 pinholes per square meter is a floor with 50 failure initiation points per square meter.
Every failure mode listed above gets dramatically worse when surface preparation is inadequate. Acid etching instead of diamond grinding. Skipping the moisture test. Not checking slab temperature before application. Not removing old sealers or contaminants. Applying over a dusty surface. These shortcuts each save 1 to 4 hours on the job. They also create the conditions for failure within the first two years. We test moisture vapor emission on every slab using calcium chloride test kits. If the reading is above 3 pounds per 1000 square feet per 24 hours, we install a moisture vapor barrier before any coating goes down. If we skip that test and the slab is wet, the floor delaminates. It is that binary. We grind every slab to a minimum CSP 3 profile using a planetary grinder with diamond tooling, then follow every pass with a two-stage HEPA vacuum so no grinding dust settles back into the surface profile and weakens the bond.
Day one starts with an inspection. We check the slab for cracks, expansion joints, existing sealers, moisture readings, and any areas of spalling or deterioration. Cracks wider than a credit card get routed and filled with a flexible polyurea joint filler. Expansion joints get honored with a backer rod and sealant because you cannot coat over a working joint without it cracking through the coating. Then we run a planetary grinder across the entire slab surface, working in overlapping passes to create a uniform CSP 3 profile. Every pass is followed immediately with HEPA vacuuming. The edges and corners get hit with a hand grinder since the planetary machine cannot reach the last 3 to 4 inches along walls. Once grinding is complete, the slab gets a final vacuum and tack wipe. We check the concrete surface profile with a visual comparator chip to confirm CSP 3. If the slab moisture test showed elevated readings, a moisture vapor barrier goes down first and cures for the manufacturer-specified time before any epoxy is applied.
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