Self-levelling floor compound smooths by itself

Ansicht von oben auf einen Tisch, der auf großformatigen Fliesen steht

Ceramic tiles are trendy. In particular, the large size tiles with edge length over 80 centimetres have been invading public areas, one-family houses and flats for some time. They make rooms look spacious and large.

Some points must be however observed when during their application. A very flat substrate is essential to make sure that the tiles have full-surface contact with the substrate and can be tightly bonded. With a self-levelling compound, you are on the safe side. For this reason, Saint-Gobain Weber has developed the self-de-aerating smoothing mortar weber.plan 813-20 for the laying of XXL formats in particular. It simplifies the work considerably so that you can obtain super flat surfaces in just a few steps.


We let out here what you need to pay attention to.

Chapter overview

1. When do I have to level out unevenness on the floor?

2. What must a levelling compound be able to do?

3. How is the levelling compound applied?

4. Conclusion

1. When do I have to level out unevenness on floor?

With a self-levelling compound, you can create a reliable base for any desired floor covering. Such a product is absolutely necessary for large format tiles or natural stone slabs. These demanding materials require an extremely smooth and resilient substrate.

The rule of thumb is: the larger the tile format, the more even the subfloor must be. This is because large tiles allow fewer tolerances in the substrate than smaller ones. If the laying surface is not perfectly flat, the tiles or slabs will lay more or less hollow depending on the unevenness. This creates an annoying hollow sound when walking and, in the worst case, can lead to breaks in the - usually expensive - XXL tiles.

To prevent this, a level subfloor is important, especially for large format tiles or natural stone slabs. They are laid using the so-called floating-buttering method, which means that the tile adhesive is applied onto the backside of the tile as well as onto the substrate.

How do I check the condition of the substrate?

The substrate must be examined closely and checked for damaged areas and slopes. A sense of proportion alone is by no means enough!

For the professional check of the subfloor skilled craftsmen use a laser measuring device or an electronic hose level. For easier orientation the specialist lays out fixed points. These also provide information about which quantity of levelling compound is needed to level out the floor.

2. What must a levelling compound be able to do?

There are various levelling compounds that differ in the composition of the mortar. As the name suggests, they can be used to level out uneven floors. In other words, they serve as an intermediate layer between the substrate and the tile adhesive. For creating slopes a non-sag (trowel-grade) levelling compound is needed. For straight and larger surfaces, levelling compounds that are machine-compatible are worthwhile. They can be easily and quickly pumped to the place of use.

How does a levelling compound work?

As soon as the skilled craftsman pours the liquid compound onto the floor, it runs out and settles to a uniform height by itself. This means that the compound no longer needs to be smoothed out. The material is poured out on the whole floor in order to obtain an optimal even surface. Depending on the subfloor, a thin levelling layer of a few millimeters up to five centimeters is sometimes sufficient. There is a suitable levelling compound for each application field. Which one is suitable, depends on the existing floor, the desired surface flooring and future requirements. The necessary layer thickness also plays a role. The minimum and maximum layer thickness are indicated on the packaging of the levelling compounds.

With product innovation like the premium levelling compound weber.plan 813-20 of Saint-Gobain Weber, there is an additional advantage: it is not only self-levelling, it also de-aerates by itself. After its application, small air bubbles are normally entrapped into the compound, which can lead to unevenness later on. For their removal the tiling and flooring specialists run a so-called spike roller over the still fresh compound. This punctures the bubbles and the air escapes. With modern building materials, this step of de-aerating is no longer necessary.

What does pumpable and flow-grade mean?

A pumpable and flow-grade levelling compound can be applied by a machine. For larger areas, it is worthwhile to use special pumping machines. The material is first mixed by the machine and pumped to the job site with a hose line. This shortens the working time and is a dust-free and clean operation. As soon as the levelling compound has been applied, the specialist carries out further work standing up. This is particularly quick and easy on the back and knees.

Levelling compound or screed?

The substrate can be levelled with a levelling compound or with a screed. A levelling compound has several advantages in comparison with a screed.

  • Short drying time - several hours instead of several days
  • Easier to apply
  • Can be applied in a thin layer. This means less wasted space, which is quite important in renovation projects.

3. How is the levelling compound applied?

The first step is the adequate preparation of the substrate. You can find the step-by-step instructions here. Old adhesive residues and loose components must be removed in order to provide a reliable bonding with the levelling compound. As soon as the floor is dry and cleaned, insulation foam strips are installed around all wall/floor connections. In this way, the new floor covering is separated from the walls.

The next step is to prime the substrate for better adhesion with the next product. This reduces the porosity of the subfloor. Depending on the type of subfloor, a different primer is required (for absorbent substrates, for example, weber.prim 801, for non-absorbent, smooth substrates weber.prim 803).

As soon as the primer is completely dry, the levelling compound can be mixed. To do this, mix the material in powder form thoroughly with the amount of water specified on the packaging, either by machine or by hand, using a mortar mixer. The prescribed amount of water must be adhered to precisely.

Then just pour out the mixed material and everything will literally run by itself: the product spreads uniformly and creates a perfectly even underlayment surface. If necessary, the liquid compound is distributed to the desired thickness and smoothed with a notched blade scraper. Depending on the thickness of the layer, the floor can be walked on after one to two hours and covered after 24 hours. With weber.plan 813-20, differences in height of 1 to 20 mm can be levelled - and even in just one work step. The material also has low emission of volatile substances. It has been awarded the EMICODE EC 1 PLUS seal. This quality seal provides applicators and residents with the certainty that almost no volatile organic substance escape from the material into the room air.

4. Conclusion

Thorough preparatory work is often decisive for a good end result. Large format tiles must lay full-surface on the substrate and be tightly bonded; therefore they need a very even substrate. When laying large format tiles or natural stone slabs, that is why a self-levelling compound should not be dispensed with. A modern levelling compound, such as weber.plan 813-20 of Saint-Gobain Weber is quick and easy to apply. It is self-de-aerating, easy to apply standing up and low in emissions. Anyone who plans to use a modern levelling compound will have the minimal additional expense and maximum safety for all common floor coverings.