Dimensional Defects

In ceramic wall or floor tiling, the term dimensional defects refers to the perception of non-uniformities in the division of the plane, produced by the joint pattern, or to the visualisation of irregularities under exposure to surface illumination, in the form of localised shadows.

This optical perception materialises, visually, in:

• Non-uniformities in the joint layout, in regard to width and alignment
• Deficiencies in planarity between adjacent tiles or between groups of tiles
• Irregularities in the pattern that, in most cases, should correspond with the rectangularity and parallelism in the surface or volume that the tiling occupies in relation to particular points of reference (carpentry, other abutting construction elements, sanitary ware, fixed furniture, etc.)

These types of defects may originate in the dimensional quality of the ceramic tile or in the tile installation process. Consequently, the ceramic technician who is to diagnose the origin of such a claim needs, first, to be quite familiar with the dimensional characteristics.

Although tile fixers say that ceramic tiles have better dimensional quality than a few years ago, it is still frequent to use ‘dimensional tolerances’ to elude responsibilities when faced with a claim based on one or more of the foregoing three points.

It should be borne in mind that output tends to be the key criterion in the tile installation process. Thus, fundamental tasks, such as a preliminary setting out of the area or control of the materials and of the fixing surfaces, take a backseat to fast installation.

In addition, while doing the installation job the tile fixer is also forced to solve all the arising problems posed by the construction elements and surfaces, including: out-of-plumb walls, departures from level, surface irregularities, inappropriate carpentry, etc.

When tiles are fixed with thin-set adhesive, surface irregularities and differences in level are usually compensated by the thickness of the applied adhesive layer, even though these are materials whose composition and characteristics in the fresh state have been designed for a given thickness. The result may be a differential settling during hardening, which leads to the appearance of so-called ‘lipping’ or other defects of planarity.

In view of such a tile fixing scene, it is reasonable to suggest that the tile manufacturers should adopt measures designed to optimise the dimensional quality of the tiles as a preventive approach and, if this is not possible, to act in relation to the dimensional identification of the product sold, with the obvious purpose of defending the innocence of the ceramic tile in the case of claims based in this type of defect.

This subject deserves to be insisted upon, inasmuch as dimensional defects, together with the impairment of surface appearance, are the main causes of direct claims against the manufacturer.

In Spain, a final consideration to be made should be the contradiction between the maximum tolerances allowed for first quality ceramic tiles, the different product groups according to standard EN 14411, and the Spanish technology standards for building construction in relation to wall cladding and flooring, respectively NTE RPA/1973 and NTE/RSB/1975. In those standards, which are only legally binding for the developer or constructor if he appears in the technical report of the project, we may find ourselves in situations of automatic non-acceptance after control of the work execution if:

• In the wall tilings, departures from parallelism exceeding ±1 mm in 1 m length tile-to-tile joints are detected
• In the wall tilings, departures from planarity exceeding 2 mm, measured with a 2-m rule in any direction of the surface, are detected
• Departures from planarity are measured in a floor tiling exceeding 4 mm, or lipping exceeding 2 mm, both measured with a 2-m rule. These maximum deviations are equally applicable to skirtings and the steps of stairs

Hence, the need to act in ceramic tile manufacturing on the process of tile dimensional control. The best technology available for the continuous measurement of dimensional deviations allows achievement of maximum tolerances well below the values permitted in standard EN 14411. Furthermore, if only calibrated products leave the factory, with a reduced number of calibres and with information that allows them to be monitored until they are installed, we can argue for the innocence of the ceramic tile in relation to the defects that are described next.

• Non-uniform joint pattern

• Deficient planatary

• Irregularities in the pattern