Tiling over a ceramic tile base

[bobob]

I am wondering wether to tile over the old ceramic floor tiles, the old tiles are tiled onto a concrete floor and are sound, the tiles are glazed and the property is in spain.
Is this a no no

 

[WetSaw]

If they're sound and you've not problem with height build up then you can tile over no problem. Make sure the floor is clean. Use an adhesive for "Porcelanico" .

 

[bobob]

Cheers, i have done it before and it was fine, wasnt sure if i just got lucky