When tiling in a wet area or where hygiene is very important, the type of grout used and more specifically its water resistance is important. So the question arises, is grout really waterproof? 

Cementitious grout 

There is a difference between waterproof and water-resistant or repellent grout. Cement-based grout is by nature porous, and therefore not waterproof. It can be water repellent when modified with an additive, either latex or polymer-based, which effectively fills the micropores in the cement at a molecular level. 

In most tiling installations. i.e., tiled balconies, showers, bathrooms and kitchens, a modified cementitious grout is suitable and should provide enough water resistance for the application. However, bear in mind that this does not eliminate the need for a waterproofing system below the tiling in areas such as balconies and showers, and in conjunction with a modified adhesive system. Suitable for areas that will be dry or intermittently wet. 

Epoxy grout 

For truly waterproof grout, the gold standard is an epoxy grout. This specialised product type is impervious, so no moisture can seep through behind the tile – it is resistant to steam and high-pressure cleaning, and it is chemical resistant. Epoxy grout is best suited for industrial kitchens, abattoirs, hospitals, food and beverage production and processing facilities, where hygienic conditions are of importance. 

Swimming pools 

Grout for a swimming pool is a specialised system. Depending on the specific requirements of the project, a modified water-resistant cementitious grout or an epoxy grout may be used. Expert advice should be sought to specify a fit-for-purpose solution.   

Issue: Is grout waterproof? 
Solution: Cementitious grout is not inherently waterproof, but there are other system solutions available. However, best practice would be to waterproof before tiling.  

Full acknowledgement and thanks go to a.b.e.Saint-Gobain,, Sika and TAL for the information in this editorial. 

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