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We have moved into an old house with terracotta tiled outdoor area which is over a garage. The tiles have areas of cracking and the grout is broken in places and was probably not waterproofed initially . There is leaking through to the garage. It is a huge area. I have had one person say that the whole area needs regrouting, and another tell me that it should have a waterproofing membrane put on top then re-tiled (which will impact patio doors opening onto it). Someone else suggested we paint a pool surround paint/sealer onto it. Is there a less expensive option that will last us for a few years?
Welcome to the Bunnings Workshop community @NicPickles. It's wonderful to have you join us, and many thanks for your question about waterproofing a tiled area.
So the issue you're facing is that underneath all these tiles, a membrane should have been put down to capture water that leaks through them. So, either there's no membrane, the water is bypassing it, or it's compromised. There's nothing you can do about that membrane unless you remove all the tiles, reapply it and then retile. You could, of course, go up, but that doesn't sound like an option.
How bad is the leak? If it's not too bad and this is just a temporary solution, then I'd suggest regrouting the tiles and then applying Crommelin 4L Natural DiamondCoat Slate And Stone Sealer over the area. This product is designed for porous surfaces, so you'll need to do a test to see if your terracotta tiles absorb water. Place some drops of water on a tile and then wait 30mins; if they absorb into the tile, you can use this sealer. If they don't, then you might just need to re-grout and seal the grout lines themselves.
Those larger sections of cracked or missing grout are likely letting most of the water through, so re-grout them. Also, look for cracks where the tiles meet walls or in low-lying areas where water might pool. Seal any cracks with Sikaflex 11FC.
Please let me know if you have any questions.
Mitchell
