Hard-wearing floors for children to play on

The time that the building stood empty, but also the many years that Villa Findeisen was occupied - built in the 1930s and extended in the 1960s on the Findeisen factory site - have left their mark. Floor coverings had worn away and the screed had come loose in places from the bond. The floors on the different storeys were also not level with height differences between 5 cm and 6 cm. Following the decision to convert the Villa into a company nursery, Uzin and Wolff, working with Findeisen, took on the challenge of removing the wear marks, levelling out the different floor heights and finding an efficient way of spreading the floor material over the widest possible area in the shortest possible time. We also needed to find a solution to install noise-reducing, non-slip and hard-wearing floors that would meet the needs of the children and their care staff long term.

Before the floor structure was installed, we had to remove several layers of adhesive, levelling compound and old flooring residues on all three storeys, as well as the dirt and dust created during the sanding process. In the attic, the grinding and milling work was done with special care, as the floor had been built on top of an older mineral screed. To work over the large area, the application engineers from Wolff and Findeisen used the Mambo EVO, which is the most versatile disc grinding machine in the tool manufacturer's range. Owing to its additional weight and higher speed, it is significantly more powerful than typical disc grinding machines. “Equipped with a basic grinding plate and six PCD Ultra diamond segments, the Mambo EVO managed to remove up to 8 mm without leaving furrows behind”, says Karl-Heinz Würth, application engineer at Wolff, explaining how even grinding was achieved. For the small to medium areas, he used the NEO 230 grinding machine. Its grinding head can be adjusted to three different angles, so that it could be guided specifically along edge areas as well. 

To remove the coarse dirt and fine dust produced by the process, the Longopac pre-separator from Wolff was installed between the grinding machines and the Vacuclean 2 twin-motor high-performance industrial vacuum cleaner, which separated out approx. 95% of the dirt and dust. “As soon as the tube of the Longopac had completely filled with dirt, it just had to be taken off and carried to the bin, tightly sealed like a sausage skin”, says Karl-Heinz Würth, describing Longopac system. This means no more dust gets out, as is normally the case when tipping dirt out of a container. Remaining dust and dirt were removed using the Vacuclean 2, which has a large filter surface area.

On the ground and first storeys, the Samba grinding machine was fitted with the Ninja ES K20 disc to grind the hard top layer of the calcium sulphate screed newly applied on these storeys.
 

The substrate was prepared uniformly throughout the building in accordance with DIN 18365. However, given the nature of the screed in the attic and the movements in the floor, the floor structure in the attic was different from the lower storeys. In the attic, subdivisions in the lengthwise and crosswise joints in the screed were found during the preliminary work. To close them, the application engineers from Uzin and Findeisen applied the “concealed joint system”. They started by filling the cracks with the hard-elastic UZIN MK 92 S wood flooring adhesive. Then they applied additional adhesive to the right and left of the crack – one trowel width away from the crack on each side. They then installed the UZIN RR 203 crack bridge, which contains fibreglass, in the adhesive and levelled it over again with the wood flooring adhesive. “Using this system, the screed sections are not cast with resin for force-fit, but are boned with hard elastic instead. This does not prevent expansion of the screed sections”, points out Ralf Härlin, the responsible application engineer at Uzin. Thereafter, the PE 460 epoxy resin primer was rolled on top, which is particularly suitable for damp or, as in this case, unstable substrates. The PE 280 dispersion primer was spread onto this layer as a bonding agent for subsequent bonding to the levelling compound. IT was dry after just 30 to 40 minutes. 

On the ground storey and first storey, the cracks were first professionally repaired with UZIN KR 516 casting and bonding resin using corrugated ties. This was because there were cracks in both the gypsum screed installed over a large area and the cement screed installed in the entrance area. In a few places where the screed was completely gone, the Uzin application engineers mixed the UZIN PE 460 epoxy resin primer with UZIN Quartz Sand XS to create a reactive resin screed quickly. New expansion strips were also installed at these points before the UZIN PE 360 dispersion primer was applied to the whole surface. It provided a base for bonding the subsequent levelling compound, as it binds surface dust and reduces the absorbency of the substrate. 
 

The Uzin pump truck was used to apply the UZIN SC 997 smoothing compound, which is a gypsum-based thin screed, quickly and at consistent quality on all three storeys. It is particularly suitable for different layer thicknesses. Depending on the height of the stairs, the balcony doors and the adjoining bathroom, the levelling compound layer was between 3 mm and 5 mm thick on the three storeys. To apply the compound, the hose of the pump truck parked in front of the building was routed via one of the staircases and the compound was pumped into the rooms from top to bottom. “This was a very efficient approach that eliminated the need to transport screed bags to the individual storeys. And it was complete in just a few hours”, says Ralf Härlin, summing up the approach. A total of five and a half tons of the screed were spread in this process. 

The relevant adhesive could be applied after just 24 hours. For the linoleum with Acoustic Plus backing, the application engineers used the UZIN KE 2000 S universal adhesive. For the textile coverings with fleece backing, they rolled on the UZIN U 2500 ready-mixed tackifier. Both products are very low-emission and have the “Blue Angel” eco-label.
 

On all floors, Findeisen's application engineers covered 310 m2 with the highly dimensionally stable FINETT DIMENSION needlefelt modules of various colours and shapes. The individual rooms are decorated with the “Fishscale”, “Hexagon”, “Tile” and “Plank” modules. These were cut on modern 3D plotters at Findeisen's factory, right next to the nursery. “You find our needlefelt in a lot of education settings. It is, however, the first nursery we have completely fitted out”, reports Marco Fischer, application engineer at Findeisen. On the ground storey, the “Tile” and “Plank” needlefelt modules are laid out in a playful pattern with a Tetris style. On the first storey, the “Hexagons” form different-coloured flowers and, under the roof, the “Plank” and “Fishscale” shapes imitate fishbones and waves. Besides the ability to customise the layout, the needlefelt modules also have other benefits. AT a height of 5.7 mm, they reduce impact sound by up to 21 decibels and withstand class 33 heavy loads. IF they ever get more heavily dirty, they can be replaced with ease, as they are not firmly bonded, but just tackified.

“In partnership with Uzin Utz, we have succeeded in completing a really great project. The application engineer from Wolff Tools was always on at short notice when we called him and he provided us with the necessary machinery. And the engineers from Uzin with their manager Thomas Schneider were always available to us when questions came up and were active on site”, says Marco Fischer, who was responsible for floor renovation for Findeisen, summing up after the work was complete. “Given the different floor heights and the choice of materials for the gypsum and cement screed, we were very happy to be able to count on the support of the Uzin advisers, who were always ready to help. And we were really enjoyed working with them”.