Why the edge of a drain fails first
A coating stopped at the lip of a drain leaves a raw edge exactly where water concentrates and sits. Water works into that edge, gets under the film, and lifts it back from the drain outward, which is why so many older commercial floors show a ring of failure around every drain while the field of the floor is intact. The fix is not a better product. It is terminating the coating over the lip and down into the drain body so there is no edge for water to find.
Falls that no longer fall
Slabs settle, and a floor poured with a proper fall to drain in 1998 may now hold a puddle two metres away from it. Coating over that reproduces the puddle in a new surface. Where the fall has been lost we grind the high side down or build the low side up with resin mortar to re-establish drainage before the system goes on. On a wash-down floor this is often the largest single item in the preparation, and it is the one that decides whether the floor works.
Trench drains and grating
Trench drains get the same treatment on a bigger scale: the resin is carried over the shoulder and terminated inside the channel, and where the channel itself is damaged concrete it gets rebuilt first. Grating frames that have worked loose are reset while the floor is open, because doing it afterwards means cutting the new floor. It is worth deciding about frames and gratings at the quote stage rather than mid-install.
Residential garage drains
A lot of Okanagan garages, particularly tuck-under builds on the Peachland and West Kelowna hillsides, have a drain in the middle of the slab and a fall toward it. That fall rules out self-levelling systems including metallic, which migrate downhill while curing. Flake and polyaspartic builds are applied at a controlled thickness and handle the slope without complaint, which is why we specify them for sloped garages as a matter of course.
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