Leaks in the bathroom’s wet areas quickly lead to moisture and water damage, which can be expensive to repair. The building regulations therefore require wet room joints to be made in such a way that they are completely waterproof.
While mortar joints are excellent between the tiles on the floor and walls, the joints in joints between floor and wall, around WC, around drains etc. should be made as elastic joints (“soft” joints). In this way, they prevent any movement between the parts causing cracks that lead to leaks. This requires a special wet room or sanitary joint, so that you increase the likelihood that the joints will be completely watertight.
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