Covering Installation Guide / Defects and malfunctions in wall and floor tilings / Defects in tile-to-tile joints
Defects in Tile-to-Tile Joints
Until recently, grout joints were envisaged in rustic floorings, in special applications in the field of publicly trafficked architecture, and in commercial and industrial ceramic tilings. In Spain there were no regulations regarding the materials for these joints or for the characteristics of their installation. In domestic housing applications, butt-joint tile installation has been a general professional practice in wall tilings and very widespread in floorings.
The butt-joint or closed joint tile installation and the general use of ‘grout slurries’ (ranging from pure white cement to mixtures of cement and sand with high shrinkage in hardening) have been the cause of numerous defects, translating into detachments of the joint material and changes in the appearance of a wall tiling or ceramic flooring.
In spite of a greater culture or awareness of quality and better information on the role of tile-to-tile joints in a wall or floor tiling, the aesthetic criterion has prevailed of continuing to fix tile without a joint spacing or with a minimum joint, in imitation of natural stone finishes. The large rectangular sizes and the commercialisation of rectified tiles pursue that aesthetic objective, in clear contradiction to the technical need of a grout joint and to the limitations that the same ceramic tile displays by its dimensional tolerances.
The sombre panorama described in the previous sections has been timidly lit up by the recent approval of European standard EN 13888, which establishes the definition, characteristics, and test methods for the evaluation of cement-based and reaction resin grouts. At least we now have a standard that sets certain minimum requirements of quality for materials specifically designed and fabricated to fill the space between the tiles, even though some points yet remain to be addressed.
Independently of the cultural perception that the tile-to-tile joint is innate to ceramic tiling, even with the possibility of highlighting the pattern by colour or finishing it in low relief, its technical function in a wall or tiling is evident:
A tile-to-tile joint should exhibit the same characteristics that are required of the ceramic tile, as well as the same level of performance. However, in addition, it should be impermeable to water in the liquid state and permeable to water in the gaseous state and, in particular, it should be deformable.
As a result of the appearance of standard EN 13888, we have some minimum assurances regarding the performance over time of the grout material; however, other characteristics are still not assured, such as yield and colourfastness, adhesion to impervious surfaces (the edge of the tile), chemical resistance and resistance to stains at the already hardened joint surface (independently of the impermeability or water absorption capacity), as well as deformability under tensile, compressive, or shear stresses, the only reference being to the characteristic of transverse deformation envisaged in standard EN 12002.
Although there are clear criteria for the assignment of defects in tile-to-tile joints, it is very difficult to separate the causes stemming from a deficient preparation and handling of the material, within the context of particular environmental conditions and in relation to the instructions given by the manufacturer, of the causes stemming from poor performance of the material with respect to the ceramic tiling in which it is located, this being understood as the entire complex of constituents and factors involved, including the ceramic tile, fixing background, aggressions of a mechanical or chemical nature to which it is subjected, in addition to the climate conditions in exteriors.
In most cases, the defects described below are a consequence, either of inappropriate handling of the grout, or poor performance in time. The most common defects, their visualisation and prevention, are set out below.
The butt-joint or closed joint tile installation and the general use of ‘grout slurries’ (ranging from pure white cement to mixtures of cement and sand with high shrinkage in hardening) have been the cause of numerous defects, translating into detachments of the joint material and changes in the appearance of a wall tiling or ceramic flooring.
In spite of a greater culture or awareness of quality and better information on the role of tile-to-tile joints in a wall or floor tiling, the aesthetic criterion has prevailed of continuing to fix tile without a joint spacing or with a minimum joint, in imitation of natural stone finishes. The large rectangular sizes and the commercialisation of rectified tiles pursue that aesthetic objective, in clear contradiction to the technical need of a grout joint and to the limitations that the same ceramic tile displays by its dimensional tolerances.
The sombre panorama described in the previous sections has been timidly lit up by the recent approval of European standard EN 13888, which establishes the definition, characteristics, and test methods for the evaluation of cement-based and reaction resin grouts. At least we now have a standard that sets certain minimum requirements of quality for materials specifically designed and fabricated to fill the space between the tiles, even though some points yet remain to be addressed.
Independently of the cultural perception that the tile-to-tile joint is innate to ceramic tiling, even with the possibility of highlighting the pattern by colour or finishing it in low relief, its technical function in a wall or tiling is evident:
- It contributes to absorbing the dimensional deviations in length and width of the ceramic tile, and to offsetting its departures from planarity, straightness of sides, and rectangularity.
- It allows water vapour to be released when the tile is impervious and there is a vapour pressure differential between the internal and external part of the tiling.
- It contributes to relieving stresses that are generated in the ceramic tiling or in the underlying layers, even though these may lead to cracking of the grout, which will always be a more discreet defect than the rupture of the tiles and which can, in any case, be corrected much more cheaply.
A tile-to-tile joint should exhibit the same characteristics that are required of the ceramic tile, as well as the same level of performance. However, in addition, it should be impermeable to water in the liquid state and permeable to water in the gaseous state and, in particular, it should be deformable.
As a result of the appearance of standard EN 13888, we have some minimum assurances regarding the performance over time of the grout material; however, other characteristics are still not assured, such as yield and colourfastness, adhesion to impervious surfaces (the edge of the tile), chemical resistance and resistance to stains at the already hardened joint surface (independently of the impermeability or water absorption capacity), as well as deformability under tensile, compressive, or shear stresses, the only reference being to the characteristic of transverse deformation envisaged in standard EN 12002.
Although there are clear criteria for the assignment of defects in tile-to-tile joints, it is very difficult to separate the causes stemming from a deficient preparation and handling of the material, within the context of particular environmental conditions and in relation to the instructions given by the manufacturer, of the causes stemming from poor performance of the material with respect to the ceramic tiling in which it is located, this being understood as the entire complex of constituents and factors involved, including the ceramic tile, fixing background, aggressions of a mechanical or chemical nature to which it is subjected, in addition to the climate conditions in exteriors.
In most cases, the defects described below are a consequence, either of inappropriate handling of the grout, or poor performance in time. The most common defects, their visualisation and prevention, are set out below.
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