Mosaic tiles, above bath, no tanking :(

13 Jan 2009
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United Kingdom

In the process of refurbing the bathroom. Have recently found this forum. Wish I found it sooner!

Situation is thus:

Pulled off old tiles, which had been in situ for > 5yrs (from before when we moved in). Came off easy, no sign of water damage on plasterboard or plaster wall. No sign of any tanking there already.

Have now tiled around bath with mostly 330x250mm tiles, apart from one vertical strip where we have used mosaics approx 50x25mm width of strip ~330mm. Grout gap is 3mm.

Have used unibond 5* "waterproof" adhesive, and unibond 5* "waterproof" powdered grout. Even phone the mfr to check is the adhesive really was waterproof, and they did indeed confirm it would prevent water reaching the substrate!

So now I am a bit concerned, since I have not tanked (there was no tanking before, and none of my DIY books said to tank, nothing on the tiles or adhesive said to tank). It's only since I found this forum that I discovered tanking.

The bath is a bath/shower combo thing, mainly used for showering. Shower is fed directly from combi boiler so not super powerful, but probably higher pressure than gravity fed or those electric things. In general use the shower will not be directed directly at the walls - the water on the walls around the shower/bath will only be "splashback" from the person in it.

My concern is the amount of grouting around the mosaics will let water through to the substrate?


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Cant say much on unibond as I personally wouldn't recommend it but i don't see how the grout can be waterproof as you mentioned. If it was a powdered form and you mixed it with water than im guessing it will be the same as every other grout (except epoxy) that is mixed with water its merely water resistant not waterproof. Ideally you should have tanked it but you'll be surprised the amount off people that don't if its just going to get the odd splash maybe it will be fine unfortunately as you've now finished the job other than ripping it off and starting again there isn't much you can do. But as i said most grouts are water resistant so hopefully it will be fine :D

Thanks for the reassurance - actually when I said that unibond tech guys said it was waterproof I meant the adhesive. Apparently there's a moisture repellant added to it.

I know people have been in this position before... it's so frustrating when the guff on the back of the tub is misleading - it specifically says "waterproof, suitable for power showers and wet rooms". :evil:

Guess we'll have to see how we go.

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You can get waterproof showerproof adhesive and as long as thats what you've used im sure it will be fine......... Happy showering lol :LOL:

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