Ceramic floor coverings made of tiles and slabs consist of inorganic raw materials, usually clays and kaolin, and can also contain quartz, feldspar and/or lime, depending on the product. Ceramic floor coverings are very wear-resistant and, depending on their water absorption, usually also frost-resistant. The variety of different surfaces and formats results in a wide range of design options.
Manufacturing process: Ceramic floor coverings are usually extruded or dry-pressed (=shaping) at room temperature and then dried. In extrusion, the individual tiles/slabs are formed as an endless strand and then cut off to a certain length. In dry pressing, on the other hand, individual tiles/slabs are pressed into corresponding negative moulds. The type of shape has no influence on the possible use of the product, which is determined by the manufacturer. In addition to the exact composition, the subsequent firing process and any glaze also determine the respective properties such as look/feel, abrasion resistance and water absorption of a ceramic floor covering.
Installation for interior applications: Tiles are usually prepared and laid with mortar or adhesives, which must be suitable for the respective ceramic material, the substrate and, if necessary, other boundary conditions (e.g. installation on underfloor heating).
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Due to the different construction heights, the type of installation must already be taken into account during the shell construction planning. For example, an in-situ concrete staircase may require a thick-bed installation due to increased construction tolerances, while a precast concrete staircase allows a thin-bed installation of the stair covering due to the more precise dimensional accuracy, with correspondingly different raw parts of the individual steps.
So-called mid-bed mortars, which are laid with layer thicknesses between 5 and 20 mm, combine the advantages of the thin-bed method with those of the thick-bed method.
There are also numerous specialized tile mortars and adhesives, e.g. with particularly fast curing (quick adhesive) or particularly high formability (flexible adhesive/mortar). Fluidized bed mortars are used in particular for the fully saturated laying of large-format tiles and slabs.
Ceramic floor coverings outdoors: The use of ceramic floor coverings glued to the substrate outdoors, e.g. as a terrace or balcony covering, is not without problems. Even when using a tile/slab material approved by the manufacturer as frost-proof and for outdoor use, damage can occur as a result of frost and steam pressure due to rainwater penetrating the bonding or joints. In addition, substances washed out of the joint material or the laying mortar can lead to efflorescence on the covering surface. When planning, it is therefore essential to ensure that water that has penetrated the structure can be drained away well. The pavement should be laid on a water-permeable thick bed, e.g. made of einkorn mortar (drainage mortar), which, in addition to the binder (trass cement), mainly contains chippings with a grain size of e.g. 2 - 8 mm. In addition, a drainage level should be placed below the einkorn mortar for safe drainage of the water, e.g. from suitable drainage plates or mats, which are laid on a substructure with a 1-2% gradient. System specifications and commitments of the manufacturers must be observed. It is structurally safer to lay ceramic slabs loosely on pedestals or in a gravel bed, but this usually requires a slab thickness of at least 2 cm.
Slip resistance: Depending on the installation location and use, ceramic floor coverings often have requirements for tested and classified slip resistance. For further information, see Encyclopedia articles ► Slip resistance according to GUV-R 181 and ► Slip resistance in wet-loaded barefoot areas according to GUV-I 8527.
Grids, sizes and formats: Most commercially available floor tiles have formats based on the 10 cm grid, whereby the grid dimension is considered the so-called coordination dimension for tile + joint, e.g. tile dimension (factory dimension) 297 mm + 3 mm joint = grid dimension / coordination dimension 300 mm, see lexicon article ► Factory dimension, joint dimension and coordination dimension according to DIN EN 14411. However, there are also different special formats, especially for terracotta and clinker brick tiles. The sizes for floor tiles range from mosaic tiles with a grid size of 0.5 x 0.5 cm to large tiles of 120 x 120 cm and more, there are already special developments with a panel size of 100 x 300 cm. Square formats are just as common as rectangular ones.
Installation pattern and joint pattern: In the case of high design requirements and depending on the tile size and the laying pattern, the tile format should already be determined during the implementation planning of a room so that a tile backsplash can be created based on it. The joint pattern is also decisive for the visual design: rectified edges enable particularly narrow joints, which almost cancel out the grid effect of the laying pattern. Calibrated tiles also allow for a finer joint than unsorted, raw tiles. Depending on the colour of the joint material, the joints can also be emphasised or weakened.
Moulded stones: Many manufacturers offer special moulded stones that are matched to the respective floor tile collection in terms of material, size grid and colour palette, e.g. for stair treads, plinths/cove plinths, as pool kerbstones or as lowered kerbstones for tiled showers.
Suitability for underfloor heating: If the ceramic floor covering is to be laid on a heated screed, the entire structure, i.e. the ceramic covering including the substructure (e.g. adhesive mortar), must be expressly approved by the manufacturer.
Chemical resistance: Ceramic flooring is usually resistant to all common chemicals. Special products are therefore only required in exceptional cases, for which, for example, increased resistance to concentrated acids and alkalis has been demonstrated in accordance with DIN EN ISO 10545-13.
Electrostatic behaviour: In certain applications, antistatic floor coverings with a defined electrical conductivity are required, e.g. if a static charge in potentially explosive areas can become a danger to life and health or if sensitive electronic components can be damaged or destroyed as a result of a static charge. For more details, see Lexicon article ► Dissipative (antistatic) floor coverings.
Stoneware tiles as floor covering: Stoneware tiles are fired at a temperature of approx. 950 - 1150 °C. Their structure is relatively porous, which makes them particularly easy to work with, e.g. drilling, but they are not frost-resistant due to the high water absorption and do not have the wear resistance of other ceramic floor coverings, e.g. stoneware . They are practically only available glazed. As a material for floor coverings, they are rarely used, especially in private living spaces.
subsoil: The subsoil must be free of coarse impurities, efflorescence or cracks. The executing company must also register concerns in the case of surfaces that are too smooth, too damp, oily or frozen or in the case of unevenness that exceeds the permissible values according to DIN 18202 gem. VOB C DIN 18352.
Readiness for covering: Laying work on a screed may only begin when it is fully ready for covering. More information on this on the bauwion knowledge page ►400 | Construction site screeds.
Element joints: The joints between the individual tiles/slabs also serve to compensate for the tolerance of the individual elements. In accordance with VOB C DIN 18352, grouting is generally carried out by slurrying in a hydraulically setting joint compound of grey hue. For specifications on joint widths, see lexicon article ►Joint widths of ceramic coverings according to VOB C DIN 18352
Spacers: Spacers are used in order to maintain the required joint width evenly. These are either part of the tile (as low protrusions along the edges, which define the required distance when laying the tiles/slabs and are completely covered when grouted), or as separate spacers (joint crosses), usually made of plastic. Particularly small-scale (mosaic) tiles are alternatively supplied glued on net supports, for which the required element spacing is already specified by the manufacturer.
Movement joints: Movement joints made of layers below the pavement, e.g. from the screed or the shell, must be incorporated into the covering in the same width, see also lexicon article ► Movement joints in floor construction. The joint is then covered either with elastic joint sealant or a corresponding profile.
Fire colours: When using ceramic floor coverings, it is important to pay attention to the same fire colours. The tiles should always be laid mixed from several cardboard boxes, for a homogeneous distribution of any slight colour deviations.
DIN EN 14411, Ceramic tiles and slabs - Definitions, classification, properties, conformity assessment and marking
DIN 18157-1, Execution of ceramic cladding using the thin-bed method; Hydraulically hardening thin-bed mortars
DIN 18157-2, execution of ceramic cladding using the thin-bed method; Dispersion adhesives
DIN 18157-3, Execution of ceramic cladding in the thin-bed process; Epoxy resin adhesives
DIN 18158, floor clinker boards
DIN 18352, VOB Procurement and Contract Regulations for Construction Services - Part C: General Technical Contract Conditions for Construction Services (ATV) - Tile and Slab Work
ZDB Leaflets, published by the Tiles and Natural Stone Association of the German Construction Industry (ZDB):
Source: bauwion
