Within these construction solutions Bostik offers a wide range of levelling compounds. Luc Wouters, floor technology business developer for Belgium, clarifies the range further. Luc has over three decades of experience at Bostik and gives technical advice for both substrate preparation and training courses.

‘Floor technology includes all products for repairs and covering floors, damp screens, levelling compounds, and wall and floor adhesives,’ Luc says. ‘Bostik has products and suitable materials for all phases of a project.’

Analyse the substrate and floor
‘Analyse the substrate and the floor,’ is Luc’s first piece of advice. ‘The levelling compound to be used depends on the substrate and the type of flooring. Whether you fit ceramics, carpet, PVC, linoleum, or parquet, all flooring has specific requirements which have to be considered.’
‘You have to take account of features such as drying time, required layer thickness, strength, and flexibility. And so, fast-drying levelling compounds aren’t always necessarily the ideal solution.’

‘With a flexible floor covering such as PVC or linoleum, you need a very flat substrate to obtain a straight result. It isn’t possible to level out any unevenness with adhesives. This is somewhat different with parquet. You can eradicate any unevenness via a greater adhesive consumption, and therefore a thicker layer of glue. Moreover, great compressive and tensile strength are absolutely essential with solid parquet because the wood continues to work into the substrate. And so, each installation requires the right levelling compound.’

Layer thickness is a criterion
Layer thickness is also an important criterion. Indeed, all levelling compounds have a maximum applicable layer thickness. Luc Wouters explains: ‘In practice not all substrates are equally flat, so you might have to absorb 4mm in one corner, with a much bigger difference in the other. The new Bostik levelling compound SL C 740 FIBER MAXI (SL = Self Levelling and C stands for cement-bound) is fibre-reinforced, has a compressive strength of 30 N/mm², and can be used for a thickness of up to 4cm.’
The next piece of advice for professionals is always to respect the listed dosage of water. ‘The last thing you want is a powdery end result. And so, you should stick strictly to the prescribed quantity of water to be added. With Bostik, these instructions are always given clearly on the pack.’
Originally, fast-drying levelling compounds were developed for application in retail and public spaces where renovations have to be completed quickly and efficiently. The closing time has to be kept to a minimum. By opting for fast-drying levelling compounds, you make it possible to fit a new carpet or tile floor after two to four hours. The fastest-drying levelling compound at Bostik is the SL C990 SPRINTER. ‘Under perfect climatic conditions you can fit a tile floor or carpet after barely two hours and a PVC floor such as LVT strips after four hours.’
Linoleum and parquet, however, require a perfectly dry substrate. Both products are simply too sensitive to damp. And so, it is advisable to wait 24 hours before fitting the floor, so there’s not much point in using a fast-drying levelling compound.’

Ecological solutions
Finally, we discuss innovations in the area of levelling compounds. ‘In the market generally, but especially at Bostik, lots of efforts are made to offer ecological solutions. For instance, all our levelling compounds have at least an emission certificate EC1 or even EC1+. And so, they are ideal for use with green projects (BREEAM and LEED).’