Wall Tiles

[fattony]

I have tiled my bathroom window sill and when someone has a shower the tiles on the window sill get wet, just recently the tiles nearest the shower have started to lift, what whould cause this?

 

[gcol]

What was the surface you tiled onto? Wood, plaster board, mdf etc...
What tile adhesive and grout did you use?

 

[fattony]

it was plaster, just used cheapest tile adhesive and grout (2 in 1) I found in wickes, is that my problem?

 

[gcol]

The trouble is, on a cill, the water will stand, pool and soak through the grout to the adhesive and base. It doesn't help that you used poor adhesive/grout cause I would expect that it will be less water resistant than a decent seperate powdered adhesive and seperate grout.
Having said that, even good adhesive and grout isn't waterproof (just water resistant). Do you understand the difference?
Anyway, water getting to plaster is not really a good thing? Are we talking about plaster or plasterboard? No matter, neither react well to water. As the tiles have blown, you need to lay a water resistant tile board onto the cill. Something like Wedi board should be ok. http://www.wedi.co.uk/using.htm
Then re-tile.