Waterproofing tiled balcony

[Christianb]

I have a balcony/patio that at the moment is covered with rubber like waterproof grey paint. It looks ugly. Underneath there are big old red tiles. I asked the builder about removing the waterproofing layer and just having the tiles that are already there but he says no no, it would not be possible to stop the water coming through into the room below!

I wonder if this is totally true; there must be some way to insert a waterproof fill between the tiles as well as in the cracked ones? It is shame not to have the pretty existing tiled-floor and have instead some plastic on top which also has to be reapplied every four or five years, I am told...

[information]

it sounds like the waterproof membrane under the tiles has leaked in the past and someone has used a paint on waterproof membrane to stop the leaks. The only way to do this correctly is to dig up the whole lot and start again laying a new waterproof membrane and new tiles. Not a small job.

[Christianb]

In this case, at the moment, I will have to check the existing waterproofing layer, and I wonder if I have to repaint it all or just look for cracks in it and patch it with the same substance?
Also is it possible to lay on top an entirely new level of tiles? There is enough room below the doors...

[delderek]

Tiling on top of tiling is done often. But in your case if the original waterproof membrane is faulty, then a new layer of tiles will not stop water going through. As information stated, the old ones have got to come up.

[Christianb]

I meant to place a new waterproof membrane as well on the top of the old tiles, before re-tiling.

[delderek]

Don't think so, the membrane normally is placed onto concrete, and then has a layer of concrete over the top, before tiling. Open to other opinions, but tiles do expand and contract, so can't see a membrane underneath one layer doing any good, long term. It is definitely not the recognised way of doing it.

[Christianb]

OK, you pals really have a strong hand, but I still have one more card to play.
I've heard that there is some kind of two component transparent varnish, that one can apply on the tiles. It takes 48 hours to settle, but then it is really hard. It was suggested to me for my internal old tiles which I would like to keep. I guess it should be also waterproof and not crack easily. Is this the ace that can do the trick, or I must try the roulette?

[delderek]

I guess really you have answered your own question, about sealers. If the room below is not getting damp from the tiles above, then the sealer that has been put on the tiles does work. So although looks bad, does work. But finding a sealer that looks good and works, could be a nice lifelong hobby. Remembering of course that if it doesn't work, it could take as long to remove as applying.

[Sundowner]

As long as the tiles are sound you could use Schluter matting and tile on top of it. Done properly it works.

http://www.schluter.co.uk/matting.aspx

Schluter is a German company and their products are available throughout the E.U.

[Christianb]

I told the builder my idea about the transparent varnish. He said it would be impossible to peel off the present sealer of the very old tiles. Instead, he suggests, it would not be expensive to place a new sealer on top and install a new layer of tiles. In Leroy Merlin, in the waterproofing section they even play a video how to do exactly this with a product called "Ceys - Agua Stop". First two layers of it, then throw a bit of sand over it, then cola cement and tiles, according to this video. Well, at least I will have to apply a new sealer, that is for sure.