cladding on top of tiles

[dexion7]

hoping to fit plastic wall cladding in the bathroom on top of the old tiles. the tiles are firm but I've read that the surface of the tiles must be sanded to provide a key - how precisely do i do this? just sandpaper and elbow grease?

also, the tiles go right down to the floor boards where the shower tray is (so the tiles were fitted before the tray) and I've read that the tray should be fitted first, why is the order important and what are the implications for my cladding in this respect? I'm going to fit a new shower and tray anyway but wondered why the tray should go in first, theres got to be a logical reason!

 

[Tigercubrider]

I'd take the tiles off. Otherwise the top will be an issue
The reason that you tile over the shower is so that water flows into the tray, not down the back

 

[dexion7]

sorry, the top of *what* will be an issue?

is the flow of the water into the tray or down behind it not governed by the quality of the silicone sealant application or does it always leak no matter how good the appliaction?

 

[jctilingservices]

sorry, the top of *what* will be an issue?

is the flow of the water into the tray or down behind it not governed by the quality of the silicone sealant application or does it always leak no matter how good the appliaction?

Its good workmanship to fit tray first, then tile onto the tray, that way all your water runs down the tiles and into the tray, if you tile first then fit tray, you run the risk of water getting through your silicon, it only takes a pin hole for water to ingress and start lying behind your tiles, soaking the subtrate. If ya wanting to sand ya tiles, use a sander or a multi tool, but make sure you wash them first, get rid of any grease, muck soap scum or whatever could be lying there, then sand tiles, but to be honest with you, I would do as tigercubrider says, take the tiles off, then put ya cladding in