Cracking of grout in the seams between tiles

The causes of grout cracking in the joints between tiles are either significant shrinkage of the joint filler or instability of the base (presence of deformations, thermal expansion, etc.). The listed factors lead to the grout crumbling and falling out. This defect can appear immediately after completion of the work (it is associated with shrinkage of the joint filler and, as a rule, this indicates a low qualification of the craftsman) or some time after laying the tiles (occurs under the influence of the external environment during operation). The reasons for its appearance are:

1. Excessive amount of water in the mixture . This is typical for joint fillers that are sealed with water. In this case, an excessive amount of water will contribute to its evaporation, which will lead to significant shrinkage of the grout mixture.
2. There are building materials in the tile joints . The presence of tile adhesive, leveling agent residues, and construction debris in the seams between the tiles leads to an uneven height of the grout layer, which leads to its uneven shrinkage.
3. The joint width is greater than recommended for the grout mixture . Manufacturers indicate in their technical data sheets the recommended joint width (or range) for each grout. Violation of this recommendation leads to cracking of the joint filler.
4. Using non-elastic grout on unstable substrates . For unstable substrates subject to deformation or thermal expansion, the use of elastic grout mixtures is recommended. To increase the elasticity of cement grout, it is recommended to seal it with aqueous latex.
5. Sealing expansion or movement joints with cement or epoxy grouts . It is recommended to seal expansion or moving joints with silicone or polyurethane elastic sealant.