A food-plant floor fails from one of two directions, and usually both. From below, moisture vapour drives up through the slab and lifts the coating off in sheets. From above, 80 °C washdown and caustic cleaners attack the resin and the joints. A 2 mm epoxy that was specified for a warehouse will not survive either.
The slab decides more than the topcoat
Before anything is quoted, the slab gets a moisture check and a look at the vapour barrier. A ground-bearing slab poured without a membrane will push vapour for its whole life. On those, a standard epoxy primer is a delamination waiting to happen — the specification needs a moisture-tolerant primer or a PU mortar system that tolerates the drive.
- Shot-blast to CSP 2–3. Acid etching does not open the surface enough for a high-build system.
- Check moisture. If it reads high, change the primer — do not change the schedule.
- Cut in coves at every wall-slab junction. A flat junction in a washdown area collects and then leaks.
- Detail the drains before the floor, not after.
When epoxy is wrong and PU mortar is right
Epoxy is hard, chemically resistant and rigid. Polyurethane mortar is a trowel-applied screed at 6–9 mm with an expansion coefficient close to concrete. In a plant with steam, hot washdown or freezer thresholds, thermal shock will crack a rigid epoxy at the bond line long before it wears through. That is the case for PU mortar, and it is a different price — quoting epoxy against a PU mortar scope is how a tender gets won and a floor gets rebuilt in eighteen months.
Typical food-grade build
- Primer
- Epoxy, moisture tolerant, by substrate reading
- Body
- High-build self-priming epoxy, or PU mortar 6–9 mm
- Topcoat
- PU or epoxy, food-contact safe, non-slip broadcast optional
- Coves
- Fillet at all wall–slab junctions
- Cure before traffic
- Foot traffic typically 24 h, full chemical cure 7 days
- Warranty
- 1–5 years wear by traffic class, confirmed at quotation
Cure windows are the part clients push back on hardest, because the plant wants to run. The window is not padding. Loading a floor before chemical cure is the third way these systems fail early.
Written by the INTRIC technical desk. If this raised a question about your substrate, ask it — send the detail and you get an answer, not a sales call.