Seven rules for installing large-size ceramic tiles and panels | by Graziano Sezzi
Once the right ceramic tiles have been chosen for a project, the next step is to ensure they are installed correctly. This is particularly important in the case of large-format tiles with side lengths greater than 60 cm (square tiles) or 80 cm (rectangular), sizes that account for a large proportion of Italian tiles.
It is no exaggeration to say that installation is the most important factor in the success of floor or wall tiling, particularly given that this kind of surface normally lasts for decades due to its technical and aesthetic qualities.
In other words, the installation process is at least as important as the choice of tile and must be given a lot of thought by the architect or homeowner.
The first recommendation is to ensure that the installation work is carried out by a qualified tile layer. Although this may seem obvious and apply to any kind of manual work, the absence of compulsory certifications means that it is important to choose a tile layer who has the necessary skills and qualifications.
In Italy, the only certified tile layers are those registered with Assoposa, a list of whom can be found on the association’s website.
The tile layer should be informed immediately about the needs of the project. A highly skilled professional will be able not only to satisfy these requirements but also to offer advice on the best approach to installation. A clear, frank exchange of views can also be useful for the designer or architect.
The purpose of this article is not to explain all steps in installation but simply to make a few important recommendations.
1. When installing large-size tiles, adhesive should be applied to both the substrate and the back of the tile (the so-called back-buttering technique) in order to ensure maximum bonding and avoid the formation of air bubbles underneath the tiling. The adhesive should be applied in straight parallel lines to both the substrate and the back of the tile. Once installed, the ceramic tile should be tamped with a vibrating mechanical plate to ensure maximum contact between the tile, adhesive and substrate.
2. Large-size ceramic tiles have rectified edges and can be installed in such a way as to create a continuous, seamless surface, a solution that has significant aesthetic and functional advantages. Bear in mind though that a continuous surface does not mean a jointless installation, as tiles should in no cases be installed with a joint width of less than 2 mm (the minimum width specified as mandatory by Italian standard UNI 11493).
3. The joint must then be filled with grout to at least two-thirds of the tile’s thickness (although more is better), taking care to remove excess. Choosing a grout with the same colour as the tile helps to create a surface with an attractive seamless look.
4. Control and expansion joints are needed to separate as far as possible the movements of the various components of the structure (concrete slab, screed, adhesive and tile). According to the technical standard, the joints in interior tiling should divide the floor up into squares or rectangles with a ratio between side lengths no greater than 1.5. The squares or rectangles can be between 5×5 metres and 6×4 metres in size.
5. Perimeter joints should also be provided wherever the floor meets other surfaces (walls), regardless of their orientation.
6. The entire installed surface should be cleaned, including the joints. Installation is considered complete only once all residues of installation materials have been eliminated.
7. So-called floating screeds incorporate radiant heating systems, a solution that is currently very popular. According to the standard, the thickness of screed above the coils must be no less than 30 mm. Before laying the tiles, the heating system should undergo a test cycle.
These are just a few guidelines intended to help anyone who is about to design or choose a ceramic tiled floor. Just one final piece of advice: don’t tire of asking for information and always insist on getting clear answers to any questions you may have. Ceramic tiling lasts for many years, so it’s worth taking a little extra time to be sure that installation will be carried out to perfection.