Tiling on tiles - which adhesive?

[neilc]

I have a house in Spain which is tiled upstairs and downstairs with old heavy tiles made from some sort of polished aggregate. I want to re-tile over the top of these as they appear to be set in some sort of concrete and lifting them would be a nightmare. My question is which is the best sort of adhesive to use? The tiles are all in great condition and VERY firmly fixed.
TIA, NeilC

 

[Stevethetiler]

You could possibly use a cement based adhesive (BAL provide a good range of adhesives - have a look at their site.

If you are even considering tiling over exisiting tiles, it is extremely important that the surfaces are completely dust and grease free which would mean giving them a right good clean (special substances available from your local tile store - just ask em)

IMHO , tiling over tiles is like wallpapering over old wallpaper or putting a nice new carpet over your old stinky one...unless you really have no other choice, i wouldnt advise it. Yes it can be done but thats just my opinion!

If its wall tiles, your adding more weight to the wall with more tiles and more adhesive...be doubly sure that exisiting tiles are very well fixed!

 

[Stevethetiler]

Also, what type of tile are you gonna tile over with? if its porcelain for example, you will need a one part flexible adhesive as the normal rapid set adhesives wont fully set under the tile as porcelain wont allow the water content of the adhesive to escape because they are not pourous.

If the substrate you were tiling onto was pourous, then that may allow for use of a different adhesive.

 

[neilc]

Thanks Steve, Sorry didn't say it's floor tiles and I'm going to be overlaying with standard ceramic ones. It really isn't practical to lift the old tiles, I tried taking a couple up and they came up with literally an inch or more of concrete stuck to them, the tiles themselves are 20mm thick. I can see it's not the ideal option but what are the drawbacks with tiling over? Cheers, NeilC

 

[Stevethetiler]

Hi Neil

By the sounds of it, if they are that well bedded and that thick....i dont think you will have a problem tiling over them.
Just ensure the surface is as clean as possible. you can buy cleaning agents from your local tile shop for the job.

Get a good quality adhesive and away you go!

Oh, point to bear in mind is that by any doorways, remember you will also be adding the thickness of the bed of adhesive and the tickness of your chosen tile - if theres already a height difference between the flooring either side of the doorways, this is going to be increased.

Can be remedied with a height adjustable carpet to smooth floor strip or smooth floor to smooth floor strip quite easily.

 

[neilc]

Thanks for your help Steve. All I've got to do now is brush up on my Spanish - now how do you say tile adhesive ................ baldosas adhesivo!

 

[Stevethetiler]

Hehe!

Dos cervesas por favor ! - a couple of beers! thats about all i know

As your in spain, your prob better of doing it yourself with all the siesta breaks ive heard they take!

Mind you, the spanish are immaculate tilers - obvioulsy due to the fact there is so much tiling in spanish properties eh?

 

[gcol]

Also, what type of tile are you gonna tile over with? if its porcelain for example, you will need a one part flexible adhesive as the normal rapid set adhesives wont fully set under the tile as porcelain wont allow the water content of the adhesive to escape because they are not pourous.

If the substrate you were tiling onto was pourous, then that may allow for use of a different adhesive.

Half right. Cement based adhesive does not go off (set) by evaporation but by chemical reaction - it doesn't matter that the adhesive can't breathe.
Porcelain tiles (as you say) are not (or should not be) very porous therefore by using an adhesive specifically designed for use with porcelain tiles will result in a better bond than by using an ordinary powdered cement adhesive. It'll still work - just not as well as an adhesive specifically designed for the task.

 

[Stevethetiler]

My error. Perfectly right (ive had a long day). yes, cement based adhesive does fully cure via chemical reaction....so it ownt still be wet regardless of the porosity of the substrate or nature of tile.