Hard Trowelled Slabs Look Great …
Why are we trowelling concrete like we’re polishing marble — only to rip it open again for flooring? 🤔
We’re seeing more and more new concrete pours finished with ultra-slick, over-burnished surfaces. Looks great, sure.
But here’s the problem:
👉 It closes off the surface so much that it kills the absorbency needed for flooring systems to bond properly.
And what happens next?
✘ Extra prep work
✘ Grinding
✘ More time, more cost, more risk
This Raises Other Questions
So here are the real questions:
- Are we over-finishing for aesthetics and forgetting what comes next?
- Are we setting ourselves up for failure later just to make it look “perfect” now?
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For Context:
At many construction sites, concrete finishers are achieving burnished, hard, power-trowelled concrete floor slabs for areas where floor coverings are to be installed at a later date, and then having to ‘diamond grind’ the concrete to make the surface suitable for the installation of floor coverings.
Where the Finish Needs to be Suitable for Floor Coverings
It is important that either the concrete placers are made aware of the need to achieve a finish that is suitable for the installation of floor coverings, or there is a value allowance to prepare the concrete floor to produce an absorbent surface.
Burnished finish concrete floor slabs are typically so hard that progress sanding alone is not sufficient to produce an adequate surface, and diamond grinding will be required to achieve the necessary surface profile and absorbency. Many floor installers in the industry do not consider, on large commercial sites, that progress sanding is sufficient to prepare concrete floors, as this process does not remove gib-stopping residues or construction debris.
Conclusion
Here’s the bottom line: where direct-stick flooring will be installed, the concrete needs to have sufficient texture, or ‘key’ for the adhesive to bind to. A highly burnished slab runs the high risk of reduced adhesion and thereby flooring failure.
This information is available for download as an information bulletin.
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