I am thinking of getting a new kitchen installed soon but under all my kitchen units i have the sheets of small mosaic tiles. would a tiler be able to tile over them or would they have to come off
You can tile over existing wall tiles if you wish, but your room will be that bit smaller.
As they are under the units (I assume you mean below the level of the worktop) I'm unsure you need to tile there anyway. Just butt the base unit up to the old tiles, and tile afterwards where you wish to, above the base units.
I know tilers usually prefer to tile from new, which would mean taking the old tiles off. Understandable really, since they have no idea how well the old ones are held. So, if you're happy that they're solid, then no reason why you shouldn't tile over.
A pedantic addition... if you tile over the existing ones, the electrical receptacles and light swithces are all going to be uncomfortabley recessed. You'll need to have an electrician reset the boxes if you can't safely do it yourself.
Here int he U.S. there are kits available that will extend the "guts" of the switches/receptacles so you wouldn't have to have the whole box removed/replaced...
Hi Clanad, whenever I tile I always put the electrical switches on the surface of the tiles and if the screws are too short to reach the boxes then I buy longer ones as Old-Geezer says. Then there is no need to move the boxes out. I have never liked seeing the whole thing recessed.
as the builder has said, as long as the old tiles are sound, there is no real reason why they can't be tiled over, the only problem with this is concealing any exposed edges at the ends of the units for example, plus making sure there is sufficient gap at the back of the hob/sink.