The term “resilient coverings” generally refers to floor and wall coverings made from carpet, rubber or PVC. One of the characteristics they have in common is resilience, a mechanical property that allows these types of material to deform so they can absorb impact or deformations without breaking.
What properties should a substrate have to make it suitable for bonding these types of material?
- Mechanical strength – Most resilient materials do not distribute the loads acting on the floor. The forces pressing down on the surface of resilient floorings are transferred almost directly to the substrate. It isn’t unusual to notice the marks (albeit temporary) left by desks and chairs on PVC flooring. The weight of these objects acts directly on the screed and skimcoat under the flooring. Generally, the compressive strength of screeds must be a minimum of 20MPA. MAPEI stocks a variety of screeds that can be used as underlayments in resilient installations, such as Topcem, Topcem Pronto and Mapecem Pronto.
- Low level of residual moisture – Even though this is a common requirement for all substrates, it becomes even more important in the case of resilient materials. PVC and rubber are essentially impermeable, so if the level of moisture in the substrate is too high, they will swell or detach from the surface. According to current standards, a carbide hygrometer should be used to measure the level of residual moisture in the screed. Moisture barriers such as MAPEI’s Eco Prim PU 1K can be used for consolidating and waterproofing cementitious screeds.
- Flatness – Considering the compact thickness of resilient materials, if any imperfections or irregularities in the substrate are not eliminated, they show up clearly on the surface of the flooring. Flatness, therefore, must be guaranteed by taking special care when making the screed. A practical way of levelling off the surface of a screed and making it flat is to apply a skimcoat, such as Mapei’s Ultraplan Eco. Ultraplan Eco is a self-levelling, ultra quick-hardening smoothing compound for thicknesses of 1 to 10 mm. Ultraplan Maxi can be used for thicknesses of 3 to 40 mm. Skimcoats are generally made from high-strength fast-drying cementitious mortars, often with self-levelling properties.
While the three requirements above are particularly important, they are not the only ones. All those working in this sector know that curing, thickness, compactness, cleanliness and other factors all play their part in the successful installation od resilient materials.