For a tile to last, it must be correctly laid. Its adhesion to the support must be perfect and durable. The preparation of this one is essential, because it participates directly in the sealing of the tiled surface. A number of products guarantee this result. For quality work, you must know them well and know how to select them according to the desired result. Beware of sometimes fanciful or inaccurate names!
Preparation of surfaces to be tiled
It is rarely possible to stick tile directly to a wall or floor without preparation, even when new. The preparatory work to be carried out depends on the condition of the work to be covered and the risks it incurs in relation to humidity.
Water-repellent additives are thermoplastic resins, usually based on synthetic latex, to be added to the top layer of a screed or wall to prevent rising damp that would eventually cause the tiles to peel off. For the application layer of a tile, siding or paving, the product is diluted with 2 volumes of drinking water for 1 volume of resin.
The coatings are used to fill the holes and cracks of the surface to be coated, as well as to fill the unevenness of the surface. The product to use depends on the nature of the support, the importance of the disorders to be filled and the situation of the structure (inside or outside). There are two main categories:
- the filling plaster, for important work, has a very gelled consistency, which allows to apply a thick enough layer without having to form, but also without risk of sagging;
- smoothing plaster, more plastic, hardens faster, which usually allows for two consecutive applications in the day. Its strong adhesive capabilities allow it to be used for localized repairs by gluing.
The product used to fix the tile on its support must ensure a seamless adhesion; it must be exactly adapted to both the support and the type of tile.
Different products and various techniques are possible. Only the sealed installation renders the tiles integral with the building and allows it to benefit from the ten-year guarantee and thus the property damage insurance. When building, it is particularly important to require a sealed installation for this reason.
The sealed installation of the tiles, called "bath blowing" or "old", is done directly on the screed, while the mortar is taking. It is essential with a tiled floor or some terracotta. On the other hand, this product is essential for laying an external pavement, especially with natural stones. Called "sealing mortar", or "finishing mortar" according to the supplier, it is wasted at the rate of 5 volumes of mortar for 1 volume of water added with a softening additive.
The adhesive mortar
Presented in powder to mix in water, it is used to tile a concrete bottom, mortar, plaster, plasterboard, healthy and regular wood, brick and old porous tiles. If the surface is very porous, it should be pre-impregnated with a tacky resin. This is usually the case when you want to tile on an old floor.
The adhesive mortar
It is a ready-to-use mortar containing adjuvant resins, which is applied in thinner layers than the thin-set mortar on a low porous plaster or cement mortar base. The application surface must be sanded beforehand, especially if it is very smooth. On a rough concrete or mortar surface, it is first necessary to make a bonding layer, either with a smoothing compound or with a leveling mortar.
Depending on the work to be done, choose the most suitable product:
- "standard" for a thickness of 5 mm at the most (laying of faience on a flat surface);
- "special" for a layer of 10 mm (necessary for some sandstone and terracotta);
- "Quick-set" to reduce the time of neutralization (for example in a corridor);
- "Special large formats" for laying tiles or slabs 50 x 50 cm;
- "Flex" for thin tiling (slim).
They are obtained by mixing a large number of ingredients (sometimes more than a dozen), but they do not contain cement.
As a result, they are not very sensitive to the porosity of the support, but on the other hand they are more reactive to the presence of moisture. To use it on a substrate exposed to rising dampness, the cement must be added with cement at a rate of 5 kg per 15 kg of glue for application on concrete or mortar, and with a plaster base the proportion is 3 kg for 15 kg of glue. On the other hand, no other adjuvant or additive is acceptable.
A specific adhesive must be used for laying tiles on an anhydrite screed.
(photos / visuals: © DIY-Prod, except special mention)
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