Calgary & Alberta
Surface Prep
Moisture is the most common reason epoxy floors fail in Calgary. It does not show up on day one. It shows up after the first winter, usually as blistering or peeling in the middle of the floor where you least expect it.
Concrete looks solid but it breathes. Air and water vapour move through it continuously, driven by temperature gradients and the relative humidity difference between the slab and the air above it. When an epoxy coating is applied over a slab with elevated moisture vapour emission, that movement does not stop. It pushes against the coating until the bond fails.
Most Calgary garage slabs sit on grade or below grade, which means they are in direct contact with soil. Groundwater and soil moisture work up through the slab by capillary action. Seasonal changes make this worse: spring thaw pushes a lot of moisture upward through slabs that were frozen solid all winter. The slab looks dry on the surface but can have significant vapour emission coming through.
Age and concrete mix also matter. Older slabs often have higher porosity and more micro-cracking, both of which increase vapour transmission rates. A slab that has never been tested should not be assumed to be within acceptable limits.
The standard method for measuring in-slab moisture is ASTM F2170, which involves drilling holes in the slab, inserting relative humidity probes, and letting them equilibrate for a minimum of 24 hours before reading. This measures the moisture inside the slab, not just the surface, which is the relevant number for coating adhesion. Surface tests like the mat test give a rough indication, but they are not reliable enough to make a coating decision on.
When slab relative humidity exceeds 4.5%, standard epoxy primer will not form a reliable bond. The moisture vapour pushes back against the coating as it cures, creating micro-voids in the bond layer. Those voids do not cause immediate failure. They create the weak points that thermal cycling exploits over the following months.
If the reading is above 4.5%, a moisture vapour barrier goes down before anything else. MVB is a specialized two-part epoxy formulated to bridge the slab surface and block vapour transmission. It adds a full day to the job timeline. It is not optional.
EFC Standard
We test moisture vapour emission on every slab using ASTM F2170-compliant in-slab probes. If the reading exceeds 4.5% relative humidity, we install a moisture vapour barrier before any coating goes down. It adds time and cost. It's also the only way to guarantee the system holds through Calgary winters.
A floor installed over a high-moisture slab often looks fine for the first few months. The failure typically appears in the first spring after installation, when soil moisture increases and the slab pushes more vapour than it did during the fall or winter install. The blisters form where the coating bond was weakest, which is usually in the center of the floor rather than the edges.
Every slab we coat gets tested with ASTM F2170-compliant probes before any product goes down. We drill, insert, wait the full equilibration period, and read. If the slab passes, we proceed to primer. If it does not, MVB goes down first and cures overnight before we continue. There is no workaround that produces the same result. Skipping the test is how floors fail.
A floor that fails due to moisture does not look like a moisture problem. It looks like a peeling floor. The cause is buried in what did not happen on the day of installation: no probe test, no barrier, no waiting. Getting the moisture situation right before the first coat goes down is the only part of the process that cannot be corrected afterward.
Get a quote on a properly installed floor — one that holds through Calgary winters.
