A glazed-surface ceramic tile is usually impervious to moisture ingress via the top surface, as are porcelain tiles which are vitrified and have an extremely low water absorption. However, unmodified cement-based tile adhesive and grout is porous due to the inherently porous nature of cement conglomerates. This can easily allow water ingress into the installation, particularly if there are cracks or pinholes/voids in the grout. 

Issue 

Water permeating through the grout and tile adhesive layers into the substrate can result in unsightly damp patches or water damage to adjacent walls, or on the ceilings and walls of the level below. There is also a risk of a compromised tile installation if left untreated. 

Solution 

Proper substrate preparation, waterproofing and the use of suitably modified adhesive and grout systems are therefore essential for tiling to “wet” areas to ensure these issues do not occur. 

While the water resistance of the grout and tile adhesive can be increased by modifying with a suitable latex additive (strictly in accordance with the manufacturers’ instructions), this does not replace the need for a proper waterproofing system prior to tiling. A waterproofing system ensures the prevention of water leaking through a tiling installation into the substrate and causing unsightly, and possibly costly, damage to the structure. 

Recommendations 

  • Water ingress and damage should be addressed as soon as a problem is detected. 
  • In most instances, the ingress of water through tile installations will occur in “wet” areas, such as showers, bathrooms, balconies, and commercial kitchens on suspended slabs (which are subjected to frequent cleaning). 
  • Use a waterproofing compound that is compatible with a cementitious tile adhesive, as the tile adhesive can be applied directly to the waterproofing, eliminating the need for a priming system or the risk of a failure of the installation if the materials are not fully compatible. 
  • If there is no waterproofing system in place below the tiles, or if the waterproofing system has failed, the most effective solution is to remove the tiles and start the waterproofing and tiling process from scratch. 
  • t is also possible to waterproof and tile over existing tiles, provided the existing tiles are in good condition and firmly attached to the substrate, not cracked, loose or hollow sounding, and the level of the current floor allows for a height increase, especially around drains and at door entrances. 
  • The best way of determining the root of the problem, is to consult a waterproofing specialist, or a professional tiling contractor with experience in waterproofing issues. 

For more information, contact TAL: 
Tel: +27 860 000 TAL (825) 
Email: taltech@tal.co.za 
Website: www.tal.co.za

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