The process of laying ceramic tiles involves three main phases, one consecutive to the other: preparation of the substrate, application of the self-levelling agent, laying of the tiles.
As already pointed out, it is necessary to ensure that the base is perfectly flat, in order to ensure the best possible laying of the new tiles. In fact, surface imperfections could create defects in the new flooring. If the surface - existing screed or flooring - does not appear to be perfectly flat, it is necessary to intervene using a levelling layer, such as self-levelling smoothing cement (ideal for laying flooring).
- with one hand, spread the concrete mix. It is advisable to use a metal trowel (slightly inclined, to obtain the desired thickness) or a squeegee.
- if it is a large surface that is being levelled, be aware of all expansion joints already in the surface/screed.
Porcelain stoneware is known for having almost no porosity, even on the side in contact with the screed (brand). This makes the bonding of the tiles to the mortar more difficult. It is therefore advisable to lay them with an adhesive, to guarantee it is secure. The choice of installation products will depend on the deformability of the base and its specific features, closely related to the dimensions of the tiles and the environment being worked on. In most cases, a large installation and clearance is recommended, and planned splitting joints between tiles (around every 20-25 m² for indoor flooring and around 9-16 m² for outdoor flooring). Below are the main installation operations:
> preparation of the supporting surface to ensure perfect flatness of the surface. Avoid cracks and splits. Clean and carefully remove the parts that are not well attached. If using cement adhesives, apply a primer if surfaces are being applied, eg. gypsum plaster.
> preparation of the adhesive necessary phase if powder/two-component adhesives are to be used (paste adhesives simply require re-homogenisation as they are ready for use). The aim when preparing the adhesive is to be able to use a completely homogeneous and fluid mixture that is easy to make and made up of components that are capable of fulfilling their purpose. For quantity and application, always follow the manufacturer’s recommendations. Note: once mixed, the mixture can be only used within a set time (depending on how long it can last). For timings, use the guidelines stated by the manufacturers.
> Application of the adhesive and laying of the tiles With a toothed trowel, proceed with the application of the adhesive. The trowel must be suitable to ensure optimal laying of the tiles. For outdoor ceramic flooring and wall tiling – in formats greater than 2cm thick – pool tiling and surfaces subject to heavy weights, also spread the adhesive onto the back of the tiles. This will ensure they are fully covered. Lay the tiles, respecting the adhesive’s timings marked on the specification sheet; remember that timings will be closely related to factors such as environmental conditions and type of underlying surface. Caution: The adhesive should not form a skin on the surface; if this skin forms, the adhesive should be refreshed by running the toothed trowel back over it.
> Laying outdoors although porcelain stoneware has frost-proof properties, outdoor tiles must comply with specific installation standards to ensure the best possible frost resistance. Here are the main conditions to be observed for outdoor installation. - incline: the incline of the floor must not exceed 2% (2cm lower per meter).
- expansion joints: to be used every 3 meters, the expansion joints cross the underlying layer and contain isolating foam material. They have the purpose of compensating for expansions and shrinkages caused by seasonal temperature fluctuations.
- joints: for outdoor environments, we recommend the use of waterproof materials.
- waterproof layer: to be installed with an incline of 2%.
- drainage: proper surface drainage will be used to remove water without pressure.
> grouting of joints using a rubber or plastic trowel, fill the joints in order to completely fill the gaps between tiles until they are compacted and smooth. Materials used: coloured pre-mixed mortars, advantageous because they can be colour-coded with the chosen ceramics, as well as having a less porous surface (which does not retain dirt).