Prior to tiles installation, much care and efforts are needed in understanding, planning and design of the whole system from the choice of materials for each layer needed to support the surface and comply with certain performance requirements coupled with needed expansion joints till the selection of methods for installation of tiles.
Upon having a sound comprehension over the planning and design of the system in totality, transition to methods and techniques of tiles installation which is of great importance to the quality and durability of the end-result over the long term can be initiated. The step-by-step procedures (as shown in the flowchart below) are to be carried out diligently in order to avoid the incidence of defects, which is to be explored in the course of our discussion.
INSTALLATION PHASES OF WALL & FLOOR TILES
At this stage, after much careful planning and design have been undertaken, installation can proceed and be simplified into 2 methods, i.e. thick-cement-mortar method for ceramic tiles that are porous in nature and thin-high-performance-adhesive method for porcelain tiles that are with low porosity. However, for ceramic tiles that are porous, desire to select adhesive method for installation can be considered but more costly if compared to conventional cement-mortar method.
At this juncture, it must be clear that even if we have spelled out from the beginning that adhesive is to be used for installation but again no effort to understand and pick the correct adhesive during the planning and design stage may still result to anchorage failure between porcelain tiles and tile bed. Thus, recommendation to remedy this effect is to seek for high performance adhesive, which under European Norm, EN Standard 1348, will yield minimum bondage strength of 1N/mm2.
Progressing from the right type of adhesive selected, further care must still be taken to avoid installation errors e.g. tiles were not correctly tapped into position, tiles were applied after the adhesive’s “open time” had elapsed, adhesive that may be adulterated at site or tiles that are not properly applied causing cavities in between tile and tile bed, which may give rise again to anchorage failure.
The procedures involved in installing the tile are as follows:-
I: Preparation of the support structure.
II: Choosing and Preparing of binder (cement mortar or adhesive)
III: Application of the binder. i.e. preparation of the tile bed
IV: Setting of tile
V: Sealing of joints
VI: Cleaning the freshly tiles surface
It is impractical within the scope of this volume to present a detailed description of each individual step of the installation phase in relation to the various operating and environmental conditions but is suffice to point out the general aspects of each step, specifying from time to time the requirements which must be met and the precautions to take in more critical situations in order to provide a sufficient basis for a correct interpretation of the defects.
As a good industry practice, evaluation on the correctness of the installation of tiles has to be emphasized based on
i) the force and tenacity of the anchorage of the tile bed between the tile and the underlying support layer (in retrospect with the adhesion between tile and tile bed, between tile bed and support layer and the internal cohesion of the tile bed itself)
ii) the technical regularity and the aesthetic quality of the joints between tile; the compactness, cohesion and chromatic uniformity of the material filling the joints of the overall tile surface when completely installed.
Firstly, the support structure must be perfectly clean, free from dust, paint, scraps, grease and oil, or other easily removed materials. In many cases, simple cleaning with a broom may not be sufficient and very careful washing of the surface is always advisable
When ceramic tiles are to be installed with cement mortars in the thick-cement-mortar method, the support surface must be first wetted with clean water to prevent the surface in question from absorbing the water in the mortar necessary for setting and hardening, thus weakening the overall structure.
The support must be flat and even, especially when adhesives in a layer (thin-set method) are to be used. It is very important that the thickness of the adhesive layer be as uniform as possible to avoid the onset of dangerous tensions during maturation.
Concurrently, the support layer must be mechanically resistant and rigid, especially in the case of floors destined to be walked on by many people or travelled over with heavy vehicles (push-carts, motor vehicles, etc). Therefore, cases like industrial environments, hypermarkets or garages, it is important to reinforce the supporting layer with a strengthening load distribution layer, i.e. concrete reinforced welded mesh.
The mortar composition (cement, sand, water) must be carefully chosen from its sources. The sand should have a suitable particle size distribution and be clean, free from clay, organic compounds and soluble salts like the river sand. The water must also be pure as it should not contain any organic matter. This is because if any of these particles are contaminated, it may give rise to issue like efflorescence or whitish powders that develop and marring its aesthetic view.
The three mortar constituents, together with any additives, otherwise called latex or admixtures, which is particularly advisable for porcelain tiles installation, must be measured and carefully mixed to obtain a perfectly homogeneous paste.
The first step is to spread the mortar onto the support surface in the required thickness, which in any case should not be less than 2-3cm. The bed or mortar must then be tamped down to prevent the formation of cavities within the bed, and leveled with an appropriate straightedge or measuring rod. For these procedures, it is worthwhile to make use of mechanical vibrators that allow both functions to be carried out correctly, easily and quickly.
When installing ceramic floor tiles that are essentially porous, the tiles should first be soaked by immersion for a length of time in clean water.
Wet tiles are laid on the bed of mortar against the appropriate strips of wood or spacers with open joints of minimum 2mm. The tiles should be pushed into the mortar but also to make sure that the underlying mortar does not ooze out between the joints and reach the external tile surface.
Adhesives supplied in the form of powders must be mixed with water, in accordance to the suggested dosages and instructions of the manufacturers. The resulting paste must be perfectly homogenized using a suitable mixer.
If two-component adhesives are suggested, the same requirement of careful homogenization with a mechanical mixer is, too, needed. Ready-to-use adhesives only require rough homogenization with a trowel.
The adhesive should then be applied with an appropriate notched trowel which allows a regular thickness of the adhesive layer to be obtained while obtaining undulating surfaces with suitably deep grooves to delineate the zones of initial contact between the binding layer itself and the tile. With regards to the choice of size and shape of the notches on the trowel, it is advisable to follow the instructions of the manufacturer. The adhesive must be applied a section at a time on limited portions of the support surface in order to allow sufficient time for the application of the tile within the established limits of the “open time” and “adjustment time” of the adhesive. (Open time is where the adhesive workability with tiles would lapse after a certain time frame which usually varies between 20 to 30 minutes depending on the type of adhesives being used. The adjustment time is the time available to modify or correct the position of a poorly placed tile after its application on the adhesive, in most cases, the minimum adjustment time is around 10 minutes).
With adhesive binders, tiles are placed on the adhesive surface and then firmly pressed into position. In this way the ridges in the adhesive are flattened and enlarged until the adhesive covers and adheres to the entire underside of the tile. This sound adhesion must be verified by visual observation of a tile removed immediately after it has been applied. In the case of installing very compact tile in an external environment where particularly severe stress is anticipated, using the floating-buttering technique is advisable. This technique consists of the application of a thin layer of adhesive on the back of the tile as well as on the support layer.
Once the tiles have been put into position, they must be uniformly and dynamically tapped into place, in order to assure accurate leveling of the surface and good contact with sufficient adhesion between tile and tile bed. It is worthwhile to use mechanical tappers or vibrators for this operation.
When installing tiles on the wall, the tiles are applied one at a time after having spread about 1cm of mortar on the masonry. Application of the tile begins at floor level; a strip of wood is positioned horizontally along the bottom of the wall to temporarily take the place of the first row of tiles if there is no sufficient horizontal baseline.
Cement grout can be used (often added with range of colorant to match the color of tiles) to seal off the joints. Beside the cement based sealer, there are various other types of sealers as grouting materials which are available commercially, for example, latex, acrylic or epoxy base sealers which are specifically meant for certain working environment with each having its own technical properties. The operation of applying the grout is carried out using a rubber or plastic spatula in such a way as to obtain complete, regular and compact filling of the joints. Machines are available, essentially rotating spatulas, which allow the grouting operation to be achieved easily and effectively.
This is the final procedure, which is to eliminate traces of grout and other materials used during the installation process. Best initial effort is to have immediate cleaning using a wet sponge or jute cloth while the grouting is still fresh. This is a delicate operation and much care must be taken not to ruin the surface of the joints.
Consecutively, a more thorough cleaning or rinsing is performed using water or mild diluted acid solutions capable of dissolving and removing the residues (specifically cement based residues) of the various products used while installing the tile. It is essential to know and understand the characteristics of the installed tiles to avoid the possibility of damaging the tile during this cleaning operation.
By this moment, the tiled surface is now completed but not necessarily ready for use. The setting, maturing and hardening reactions of the tile bed must be permitted, which require a certain gestation period, as it would determine the quality of adhesion between the tiles and tile bed and between tile bed and the support structure.
Simply, if adhesives have been used, the instructions of the manufacturers are to be followed. If cement mortar has been used, a longer gestation period of at least 20 days is needed for setting and hardening process to take effect before subjecting the tiled surface to the normal stress of working conditions in order to avoid any risks of various defects.