Tile laying – the various steps | by Alfredo Zappa
The operation generically referred to as “ceramic tile laying” consists of a complex series of complementary activities: analysing the project and the substrate and planning the work; checking ambient conditions; checking that the materials have been stored correctly; applying any preliminary layers that may be required; cutting, shaping and drilling; preparing the mortar or adhesive and laying the tiles; applying grout; installing deformation joints; cleaning and protection; disposing of waste; testing and acceptance.
The key players
The designer: draws up the installation project and oversees the executive stages if he has been appointed to supervise the work. He is present at final testing.
The client: sets out the technical and aesthetic requirements in collaboration with the designer based on the intended uses of the spaces and the stresses they will be subject to. Performs testing himself or through an appointed technician.
The tile layer: draws up and discusses the installation programme. Checks the state of the substrate and makes an official report on any deviations from the project. Performs a preliminary tile layout test to optimise the installation pattern and minimise cutting. Checks the quality of the materials to be used (tiles, adhesive, grout, etc.) and that they have been correctly stored. Installs the tiles in accordance with the requirements of the project and the indications of the works manager. Protects and looks after the work through to handover. He is present at final testing.
The operations involved in tile laying are discussed in UNI 11493. The following are a few key aspects, although reference should be made to the standard for further details,. Ambient conditions (rain, wind, sun, frost) must never reach levels such as to adversely affect installation work, which must not generally be performed at temperatures (of the air or materials) below 5°C or above 35°C. The materials must be stored strictly in accordance with the manufacturer’s instructions and in suitable storage conditions. The tile layer must make an official report of any defects. As for the stage of preparing the installation materials and laying the tiles, the tiles must be mixed prior to installation to ensure a homogeneous finished result. Some porous tiles installed with cementitious mortar must be soaked in water in advance to prevent them from causing the mortar to dehydrate due to water absorption. In the case of installation with adhesive, special attention must be devoted to the “open time” and “working time” and to the appropriate choice of notched trowel. Once the adhesive has set and spacers have been removed, the next step is grouting. The spaces between the tiles must be empty down to at least 2/3 of the tile thickness, or the entire thickness in the case of thin panels. Cleaning must be performed correctly following complete elimination of all installation residues and taking care to avoid causing abrasion or chemical damage. Testing must be performed before the tiled surface is used and includes: visual inspection at a distance of 1.5 metres; measurement of evenness of the surface in accordance with UNI 11493 – Point 5; checking for loose material, if necessary by tapping the surface; visual inspection of grouting (compactness, absence of dust, cracking). At the end, a test report and client acceptance certificate may be drawn up.