Slab Tolerance Fixed with Ardex Self-Leveling Underlayment
When a concrete slab sits outside finish-flooring tolerance, Ardex self-leveling underlayment brings it into spec. We install the full Ardex system, primer, pour, level, cure, so tile, plank, and polish contractors get the flat substrate they need. Free written estimate.
A slab that is out of tolerance cannot be fixed by the finish flooring itself. Tile will crack, plank will rock, and polish will show every high and low spot. The slab has to be brought into tolerance first, and that is what Ardex self-leveling underlayment does.
We apply the Ardex primer to the prepped slab, pour the SLU to the target depth, and let it self-level to a flat plane. The bonded primer ensures the new pour stays attached to the existing concrete permanently. This is the Ardex-system approach, and it is what finish-flooring contractors expect when they see the Ardex name on the substrate.
We laser-scan the slab to find high and low spots, calculate the depth needed to bring the slab into the finish-flooring tolerance, and confirm the plan with the tile or plank contractor.
Grind and prime
The slab surface is diamond-ground to Ardex profile, cleaned of dust and contaminants, and the Ardex primer is rolled across the entire area. The primer is what bonds the SLU to the concrete below.
Pour and level
Ardex SLU is mixed to spec water ratio, poured across the floor, and allowed to self-level to a flat plane. The material has a working window; we move quickly to use it within that time.
Cure and hand off
The SLU cures to Ardex schedule, the final flatness is verified against the finish spec, and the slab is ready for the next trade to install tile, plank, or polish.
Scheduling and specs
Planning SLU Into the Build
Ardex SLU works best when scheduled with the finish-flooring contractor, not added as a last-minute fix. We coordinate the pour date, agree on the target flatness, and deliver a slab that the next trade can install on without surprises.
If the project also needs Ardex overlay or waterproofing, we spec those into the same system. The full Ardex range works together, so one project can use SLU for substrate, overlay for finish, and waterproofing for below-grade areas.
Bonded primer, tolerance specs, depth ranges and coordination with finish trades.
Ardex offers SLU products that can feather to extremely thin edges (essentially a few mil) and pour up to substantial depths for major tolerance correction. Product choice depends on the tolerance and project; we spec from the Ardex range.
Yes, critically. The Ardex primer is what bonds the SLU to the existing concrete. Without it, the SLU delaminates over time. Skipping or substituting the primer voids the Ardex system warranty.
Sometimes, with the matched Ardex polishable or top-coated overlay product. Most projects use SLU as substrate for tile, plank, or another finish; using it as the finish itself requires a different product spec.
Foot traffic typically the same day or next; finish-flooring install usually waits longer for the SLU to cure and dry to the finish spec. The cure schedule is in the project handoff.
Cost depends on depth, area, and existing slab condition. We provide a written quote based on the actual project; budget guidance can be discussed during the assessment.
They prep with Ardex primer like the spec calls for, not a generic primer. SLU bonds properly, my tile install goes in on a flat substrate. The Ardex-system difference is real.
Z. T5
Tile Contractor, Oshawa
★★★★★
Coordinated the SLU pour with my schedule, agreed the target tolerance up front, hit it on the pour. My plank install ran without complaint. Trade coordination at its best.
Y. T5
Finish Floor Installer, Toronto
★★★★★
Three different substrate areas with different tolerance issues, three different Ardex SLU products specced. Each one matched the conditions; the finish-flooring went over each cleanly.
Q. T5
GC, Brampton
★★★★★
Tight feather-edge work at door thresholds where standard SLU would not work. They used the right Ardex product, feather edge held, no telegraph through the finish.
X. T5
Custom Home Builder, Mississauga
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