Changes in materials and construction methods in the built environment have led to an increase in problematic subfloors, which lead to poor end-results, says flooring distributor Polyflor SA CEO Tandy Coleman.

These changes include the addition of chemical additives in concrete manufacturing, the increased water ratio in cement, power floating and fast-tracking building programmes.

She also advances that changes in construction techniques, such as changes in the types of surface beds and suspended slabs, have affected the way structures are designed.

While there are time, cost and environmental benefits to these structural changes, they also have an impact on the subfloors that a flooring contractor has to work with.

Coleman stresses that using a self-levelling screed can help to get a Class 1 quality screed.

Self-levelling screed is polymer-modified cement that has high flow characteristics and, in contrast to traditional concrete, does not require the addition of excessive amounts of water for placement, she adds.

Checks have to be in place to make sure that the screed is dry enough, and also that the screed is hard and smooth enough on which to lay the vinyl floor covering. This should be done using proper testing equipment and by qualified flooring installers.

Coleman points out that Polyflor promotes the use of instruments such as the Wagner meter and Protimeters prior to the installation of the floor covering, to ensure that the subfloor meets the standards required for a successful vinyl installation.

Both meters enable the contractor to accurately gauge the relative humidity, or moisture, on the screed, and allow for further drying time if necessary. Should the screen be too wet, a moisture barrier should be applied to the screed to mitigate any moisture risks. “The moisture barrier would normally be a cementitious or epoxy-based product that prevents moisture vapour transmission into the screed.”