I've installed ceramic tiles in the bathroom around the tub (all the way up to the ceiling) but what can I use to (somewhat) waterproof grout?

While on the tiling, I also want to replace floor tiles, however, right now floor is a bit lower than the rest of the house upstairs so I wanted to tile over existing tiles, how smart is that? Tiles now are in great shape, I just want new color. There are no cracks at all, very sturdy.

Tiling on on tiles is not recommended since the bound will not be strong if they are glazed and fired tile. You can raise the height of the floor with different thicknesses of Hardiebacker or cement board. Grout is a cementacious material and is not 100% waterproof but is sufficient for a shower. You could use a 2 part epoxy grout which is waterproof and stain proof but it's a bit of overkill.

You can't waterproof grout, but you can apply a sealer which slows penetration and makes cleaning easier. Any waterproofing required is done before the tiles are installed by the use of membrane either sheet or liquid.

I disagree with ballenger about installing new tile over old tiled floors in good condition. It can and is done with good results. The old floor must be in good shape and solid with not loose tiles, cracked or missing grout which would indicate movement in the substrate. Clean the floor, abrade using a carborundum rub stone or belt sander. Use a high quality modified thin set that states it's OK for that purpose.

You say the floor is lower than the rest of the floors. That's kind of unusual, why is that? Do you know how the tiles were installed... the method I mean? Is it original, how long has it been in place?

Jaz

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Originally Posted by JazMan

You can't waterproof grout, but you can apply a sealer which slows penetration and makes cleaning easier. Any waterproofing required is done before the tiles are installed by the use of membrane either sheet or liquid.

I disagree with ballenger about installing new tile over old tiled floors in good condition. It can and is done with good results. The old floor must be in good shape and solid with not loose tiles, cracked or missing grout which would indicate movement in the substrate. Clean the floor, abrade using a carborundum rub stone or belt sander. Use a high quality modified thin set that states it's OK for that purpose.

You say the floor is lower than the rest of the floors. That's kinda unusual, why is that? Do you know how the tiles were installed...the method I mean? Is it original, how long has it been in place?

Jaz

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The floor was even but I had really thick plush carpet installed in the hallway so now ceramic tiles appear much lower, so when I install new ones over old ones they'll be even.

Should I sue the net/mesh when installing over existing tiles?

Oh my. I will vouch that installing new tiles over old is not the best way to go. If you do that - and don't do it right - all kinds of not so nice things can happen - then you will end up having to tear everything out and two layers to boot.

Yes - you can spread over your old tiles. Now will this tile and additional floor leveler be at the right height after you install over the existing? Things to consider. Then you have to raise the trim, and cut it to fit. The bottom of the door. Let's not forget the plumbing fixtures , etc. Am I giving a better picture of this?
Do it right the first time.

If you use a sealer - do not use a spray on sealer - you may end up breathing in more then you apply. Not so good. They have some sealers now out that are better and you have to apply them with a brush or some tyep of applicator.

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Originally Posted by cyberheater

Oh my. I will vouch that installing new tiles over old is not the best way to go. If you do that - and don't do it right - all kinds of not so nice things can happen - then you will end up having to tear everything out and two layers to boot.

Yes - you can spread over your old tiles. Now will this tile and additional floor leveler be at the right height after you install over the existing? Things to consider. Then you have to raise the trim, and cut it to fit. The bottom of the door. let's not forget the plumbing fixtures and etc. Am I giving a better picture of this?
Do it right the first time.

If you use a sealer - do not use a spray on sealer - you may end up breathing in more then you apply. Not so good. They have some sealers now out that are better and you have to apply them with a brush or some tyep of applicator.

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That's the sealer I got :)

As far as new tiles over old ones, I am remodeling whole bathroom, new trim, paint, doors, fixtures etc. so no issues there

I'm going to side 100% with Jaz on this one. Tile right over the old, just like Jaz said, providing it's in pristine shape and height buildup won't be an issue. In your case, height build up seems to be desirable, so go for it. I will say give the thinset an extra day to set up before grouting since you will be setting essentially an impervious surface over an impervious surface and for those that wish to argue, Tile over tile, TCNA method TR712 for floors, TCNA TR713 for interior walls, you just have to know what you are doing, beyond just lick it and stick it and while you will have a reduced shear strength bond of the thinset, as long as you maintain clear perimeter spacing, free of thinset and grout, there will never be any forces affecting the shear strength.

For "waterproof grout" there are epoxy grouts you could use on the floor and there are portland cement based grouts that cure so dense they won't accept sealers and there is an additive "grout boost" which creates such a densely cured and highly stain resistant grout when used in place of water. No matter what, though, if you want truly waterproof, it's done behind the tile. I realize it's been a few days since your last response, but how about sharing where you are at on your project and the scope of what you are doing.

This product is what you need "Sunarmor" . This might solve all your problem. Hope this stuff helps. Thank you.