hi guys. can anybody tell me when tiling on top of existing tiling can i butt the tiles close together or is it essential to leave at least 3mm for grouting. i know i will have to use flexible cement but i don't want to have grout lines if at all possible.
thanks

What are the existing tiles fixed to, what tiles are they and what tiles will you be fixing...personally would not reccomend tile on tile..

hi ,you will get different opinions on this subject but i wouldnt reccomend tiling onto old tiles

it will no doubt exceed the safe weight limits that the wall should be holding

also if you are going to go ahead with this you must leave a grout line

what type of tile are you considering fixing is is stone?

and is this a water area?

Hi and welcome. You must always leave a joint between tiles. Is this a wall or floor? As above, what tiles are they and what tiles are you hoping to fix? IMO it is very bad practice to tile onto tile at the best of times. I would definitely recommend removing the existing tiles and going from there.

hi guys, thanks for your comments. it would be almost impossible tpremove the existing ceramic tiles. i am in spain and tiling both floor and walls of a bathroom. the existing tiles are tiled onto floor, a concrete sub base and walls, spanish bricks which are pretty fragile. both the bathrooms in my own house have been successfully tiled over with porcelin tiles with a grout line. this is for a friends house who would like it without the line and i advised her against this.
i just wanted to get some professional advice so that i could tell her for sure not to go ahead without the grout line.
thanks guys for reafirming my advice. you have all been very helpfull

If these are a glazed/gloss tile then standard modified adhesive will not work..

Step up to a S2 adhesive and make sure the tiles are cleaned prior to tiling..

There are also primer you can use to obtain optimum grip but whether they are available in spain is another question..

Mapei eco-prim grip is a new one.. bit like a slurry coat but ideal for over tiling..

This one.. do a search with Mapei Spain..

MAPEI adhesives sealants chemical products for construction

As above, there are plenty of adhesives that will fix tile on tile. The big question is how were the original tiles fixed? will they support the extra weight of the new tiles? always a lottery imo.

Ardex also do a primer for tile on tile don't no what the avalibilty for that in Spain is but worth a try