Steel as a floor covering? Unusual, but not impossible. Formenbau Staiger GmbH in Königsfeld-Neuhausen opted for the unusual floor design in the entrance area of their company building. For the commissioned master company Weisser Fliesenarbeiten, this meant laying XXL slabs with a high coefficient of expansion on screed with underfloor heating. Not an everyday job!

The idea of laying steel slabs in the new company building came from the company owner himself: Udo Staiger had seen the unusual floor covering in a hotel in Austria. When planning the new company building, it was clear to him that steel would be on the floor in the entrance area. With the 285 x 150 centimeter tiles, the flooring is a real eye-catcher and at the same time tough. The contractor commissioned the company Weisser Fliesenarbeiten from Königsfeld-Erdmannsweiler with the tile laying.The family business turned to PCI to meet the challenge. PCI specialist advisor Markus Nagel was at their side from the start and was also on site during the application. This free service is part of the full range of products and services for PCI Augsburg GmbH.

Large formats made of steel
Laying large-format tiles and slabs is more time-consuming and complex compared to standard formats. “The processor must know the material-specific and application-related special features and take them into account. Then laying is not rocket science, ”explains PCI consultant Nagel. “In the present case, the high expansion coefficient of steel is an important criterion. Steel expands more when there are temperature differences than conventional laying materials.” And there is the small proportion of joints when laying the large-format steel slabs: joints reduce thermal stress and shrinkage stress. At Formenbau Staiger, however, this was only possible to a limited extent due to the small area involved. The underfloor heating installed in the screed also aggravated the construction site situation.

The substrate is decisive
In the case of large formats, the preparation of the substrate is decisive for perfect execution. Its evenness must be well below the stringent requirements of DIN 18202 with a tolerance of three millimeters per meter. Depending on the type of substrate and the application, processors must use a suitable filler and leveling compound. And the following applies: the more carefully the leveling work is carried out, the easier it is to lay the floor covering. The two master tilers, Weisser, carried out the leveling work on the recommendation of PCI specialist advisor Nagel with the wash and protective primer PCI Gisogrund and the floor leveler PCI Periplan Extra. This was followed by PCI Seccoral 2K Rapid for stress relief: The waterproofing slurry was the decisive component of the recommendation by PCI. It was this flexible intermediate layer of around three millimeters that made the floor structure and laying the steel slabs possible.

Adhesive and steel must bond
In the next step, the actual laying of the slabs, the processors had to master the challenge of adhesive bonding. The solution was to prime the steel slabs with the low-viscosity special primer PCI Epoxigrund 390. For the perfect bond of the flexible mortar, the processors scattered the reaction resin primer, while still fresh, with an excess of fire-dried quartz sand 0.2-0.7. After the primer had hardened they brushed off the excess quartz sand: a rough, non-slip surface was produced. This procedure offers the greatest possible reliability. Healthy building is also guaranteed: The primer is solvent-free and very low in emissions in accordance with GEV-EMICODE EC 1 R.

Reliable bond
The slabs were laid in the combined method with PCI Flexmörtel S2. The tile adhesive was the last decisive component for the reliable laying of the slabs. The highly flexible mortar compensates for temperature fluctuations and substrate stresses. Its high adhesive tensile strength achieves the double value as required making it the ideal solution for large-format slabs on heated screeds.

PCI Flexmörtel S2 is also very low in emissions according to GEV-EMICODE EC 1 R. The silicone sealant PCI Silcoferm S was used for the elastic grouting of the large formats.

The master tiler company Weisser carried out the laying work with three employees within two weeks. Both processors and contractor are enthusiastic about the result, and both agree: “With Markus Nagel we had a very competent specialist advisor at our side. The floor structure was carefully thought out and the products were optimally chosen. For future projects, we will certainly rely on his expertise and good support throughout the entire project again! "