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Smooth, flat & level

by Darren
Pharaoh Jnl 3 15

Getting an in-depth and honest appraisal of the causes of a substrate’s downfall, and the crucial role a sound substrate plays before even considering installing a floor.

When walking into a room with a beautiful floor and a happy (if somewhat surprised) client, one knows it’s a job well done. The goal is a satisfied client and a satisfied flooring contractor with money in the bank – and this can be achieved if the entire system has been done right, from the very beginning.

Resilient floorcoverings such as LVT, Vinyl, Rubber and Linoleum are all dependent on what lies beneath. Floorcovering manufacturers, specifying authorities and organisations setting the standards all require a sound, smooth, uncontaminated, dust-free and dry substrate. “Level” is not always included in the list, but is often the cause for conflict on site.

Each of these requirements contains a multitude of potentially problematic situations.

Sound
This is dependent on the construction of the concrete slab and screed. If good quality materials were used in accordance with correct mixing and application processes, with well-planned joints, one will encounter a “sound” substrate. Signs of inferior components and processes become evident when scrutiny reveals the following:

Shrinkage of the concrete

This crack is symptomatic of shrinkage during curing where no joint was engineered into the slab, with subsequent cracking right through the slab. This will need remedial work by the main contractor.

These cracks are also due to shrinkage, but are not of significance. They often occur when bleed water from the drying is re-worked into the concrete surface, or the concrete is steel-floated too soon after pouring.

Hairline and fine cracks need close examination to determine if they are indicative of delamination.

Cracking and delamination occur where the bleed water from the concrete curing has been used to create a “granolithic” finish by adding dry cement powder and then steel-floating. The crust is poorly bonded and is a significant weakness in the substrate.

Cracks such as these may be indicative of more serious screed delamination problems, with the only “good” solution being to scabble the screed until a sound substrate is achieved.

When encountering any of the above visual effects, inspect the floor carefully, tapping with a steel rod to hear whether there are any indications of hollowness. This communicates how sound the substrate is. If in doubt, ask for advice from technical staff who will gladly do an assessment and provide intensive reports and recommendations.

Smooth approach

All of these flooring types mirror any defect under them, no matter how small. Older-generation smoothing compounds are by their very nature inclined to leave trowel marks, which are visible through the flooring.

Smooth, flat and level surfaces contribute positively to the flooring’s overall appearance. Often a levelled surface is confused with a flat one. A concrete substrate is often uneven and not levelled, which requires the application of a self-levelling compound such as LEVELite F30 to achieve an acceptable finish. However, in extreme cases, the sheer amount of material needed may prove to be too costly.

The solution: focus on a subfloor that excels beyond expectation, because only then can a successful flooring installation be guaranteed.

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