What to grout and seal my outdoor tiles?

[anshul]

Hi!

I’ve recently tiled my rooftop terrace (outdoors, obviously), and noticed that rainwater had gotten stuck under them and was dripping into the rooms below. While I’ve tackled the problem of this stuck water separately, I want to ensure that more rainwater doesn’t seep through the tiles again.

I realized that the low-quality grout we had used was not water resistant, nor had a waterproof sealer been used. I’m now planning on removing this grout, and replacing it with something more resistant, as well as using a sealant to prevent further leaks.

Does anyone have any recommendations for suitable outdoor grout products, as well as a sealer I could use for them? This house is overseas and subject to the monsoon period, so rain is pretty uncommon, except quite intensely for a few  months of the year.

Any help at all would be appreciated, as well as other tips to help waterproof the roof tiles further. 

Thanks!

[Jewelleryrescue]

Tiles are pretty much used  for decoration there  ideally should have being a waterproofing membrain under the tile glue  bed and you  will never think twice about a leakage.

So the best option is to take the tiles off and apply a water proof membrain before  retiling. for a great long term  solution for the  life of the house.

But with tiles allready  down the  best  grout is  epoxy  grout its  not  cheap but if  installed correctly may solve your water problem with out having  to seal any  thing unless your  tiles are porous ?    Then  your  will need a  high  quality sealer from  the nu tech range of water based out door sealers I trust to do the job.

You   could also  epoxy over the whole tiles and seal them  that way as an extreme  measure  and the  epoxy is  UV resistant not 100% proof  so  best to shade it.

[JacobZ]

Hi @anshul,

A warm welcome to the Bunnings Workshop community and thank you for your question.

Generally, in outdoor applications, a rubberised waterproofing membrane is applied beneath the tiles to protect the substrate, whether it is concrete, fibre cement sheeting or timber.

Grout is not waterproof, which is a common misconception in tiling. Grout is designed to fill the gaps between tiles and provide a smooth, finished surface, but it is inherently porous. This means it can absorb water, particularly if it is unsealed. Over time, moisture can penetrate the grout, potentially reaching the substrate underneath the tiles, which can lead to problems.

Grout sealers are designed to make cleaning and maintenance of your grout easier, not to make them waterproof. They will make your grout somewhat hydrophobic, but not truly waterproof. You can use a grout sealer like this Dunlop Grout Sealer to add some protection to the grout, but it will not make it waterproof. 

If you want to stop the water from dripping through completely, you'll need to remove the tiles and waterproof the rooftop terrace. This will involve applying an exterior-grade waterproofing membrane and accessories, such as wall flashings and drains, that are relevant to your circumstances.

Let me know if you have any further questions.

Jacob