occurrence, damage, legislation


Tests by Ghent University and WTCB

More insulation in the floor structure, tiles that are larger and harder pressed, but still the same screed. This naturally leads to damage/problems, which the BBRI and Ghent University mapped out via the research project (TETRA/IWT project) and bundled them into the Pocket insulated interior floors. Staenis carried out exactly the same tests and solved all problems with floating floor screeds, so that thick insulation layers and the new larger tile sizes are no longer a problem.

Current claims/issues

Cracks and loose joints

Crack in the tile floor

This damage occurs due to significant shrinkage stresses of the screed in combination with the heating and cooling of the floor structure due to weather conditions and the underfloor heating.

expansion joints

Expansion joint in the screed and tile

Expansion joints must always be respected with a normal reinforced screed, which looks less attractive from an aesthetic point of view. If these are not inserted, the screed will separate.


Sagging of the insulation layer and 'dishing/cupping' of the screed

This damage pattern is created by deforming the normally reinforced screed and causing a depression to form in the insulation layer. This is called the arching/dish forming/cupping of the screed.


BBRI legislation TV 237


Technical Information (TV) are publications of the BBRI that serve as a guideline for working in various fields of construction. This Technical Information no. 237 provides general guidelines for the installation of ceramic interior floor tiles.

Crossed tiles or tiles + 60 cm on vvw

Laying pattern tiles crossed joint

Tile sizes of up to 3,600 cm² (e.g. 60 x 60 cm) on underfloor heating are permitted without the use of preventative systems, as long as the general installation rules with straight joints are observed. Staggered installations (tile bonding) are best avoided on heated floors and terraces.


Screed areas with expansion joints

In order to reduce thermal movements in the screed to a minimum, the length of the screed areas should be limited to (5 to) 8 m and the surface area to 40 to 50 m². When positioning the expansion joints, always aim for rectangular areas with a length-width ratio of two at the most.

Solution = Staenis grid

Compartment of the screed = tension-free screed

Traditional screed vs Staenis floating floor screed Dish-forming/cupping effect screed floor construction

The tables above show you the vertical displacement against the number of days after installation of the screed (with 250 kg cement/m³). Here you can see that a traditional floating floor screed with reinforcing mesh or fibres is uneven by up to 5 mm in the corners, while with the Staenis grid all values are 10 times lower and there is therefore no curving / dish formation / cupping of the screed occurs. This means that floor coverings can be installed faster, easier and without risk.

Replaces the iron reinforcement net = savings of an average of 3 euros/m²

Reinforcement net no longer needed due to Staenis grid

Basic information about screed: It is important to know that a standard screed (a mixture of sand, cement and water) after installation will shrink on average 0.7 mm per metre when it dries out. For example, with a screed of 8 cm thick, the top 2 cm will dry out the fastest. As a result, the screed wants to shrink in the top 2 cm and it will show cracks or a cupping effect, which is reflected in the rising of the sides and corners of the screed. The tiles are often laid at this time. Over time, the screed dries out over the full thickness, via the joints and sides of the floor. This will also cause a shrinkage in the lower part of the screed. As a result, the tiles and screed come under enormous stress and there is a great chance of cracked tiles, loose floor coverings, etc.

The Staenis grid divides the screed in such a way that the tensions are divided enormously. No or few other tensions = no shrinkage damage and slumps after a few years.
A standard reinforcement mesh or fibres are designed to reinforce screed without an insulation layer. Now with the arrival of the thick insulation layers and the new tile formats, these cause many problems.

Replaces an uncoupling mat = savings of an average of 30 euros/m²

The Staenis grid is a cheaper alternative to decoupling mat

The Staenis grid divides the screed into areas of 0.5 x 0.5 m. This distributes the cupping effect and expresses itself at least per compartment. In this way, the screed remains supported on the substrate and the tiles (floor finish) do not experience any tension, making an uncoupling mat (+gluing) of €30/m² unnecessary. This can quickly save you €1,500.00 for the surface area in the living room and large spaces.

No expansion joints needed in the screed = savings of an average of 3 euros/LM

No expansion joints in the floor finish

A traditional screed is always divided by an expansion joint after an average distance of 6 to 8 metres, depending on the type of floor covering and whether or not underfloor heating is present. Because there is an expansion joint every half metre with the Staenis grid, it is unnecessary to place a real expansion joint, either in the screed or in the tiles. In this way a great-looking end result is obtained. Keep in mind that an expansion joint still needs to be placed at apertures smaller than 110 cm.

Much faster start-up of underfloor heating possible = faster construction process

Screed with underfloor heating can be tiled faster thanks to the Staenis grid

The waiting time to start the underfloor heating protocol with a traditional screed is 28 days. After one or more cycles of the underfloor heating, you can start installing the floor covering. With the Staenis grid you can start the underfloor heating start-up protocol after 7 days and always place the floor covering after 28 days, regardless of the thickness of the screed.

Calculate the quantities and visit our webshop

Staenis webshop

You can find all products/articles related to floor structures on this webshop.

  • Such as screed, stabilised sand and drainage mortar supplied in a silo
  • (tileable) insulation screed supplied in bags
  • Recycled cellular concrete granules supplied in bags.
  • As well as the installation material to place these flat, such as the Staenis grid, sanding board and screeding iron.
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