Tiles discolouring

[Peter]

Done a bathroom for a builder about a year ago. He told me that one 150mm wall cut to the shower tray had discoloured and the cut beside it on the outside of the shower had also discoloured. The tiles were a cream 600x300 ceramic with a very red biscuit and were onto tanked skimmed block. The builder and customer are not too worried about it and the builder will pay me for fixing it but just wondering what has caused it and how to prevent it again? Do you think it's coming through the block from behind or water getting through the glaze of the tile? It's only those two bottom tiles and nowhere else.

 

[White Room]

Is water creeping into those two tiles causing discolouration...

 

[DHTiling]

Is the seal at the base still intact. ?

 

[foggy34]

water in the biscuit of the tiles at a guess-maybe sealant issue or some cheaper ceramic it maybe creeping in at the egdes?

 

[Time's Ran Out]

Could be where the shower screen has been drilled through the tile! Some of these frames allow for the water to run through the middle and drain out at the tray.
Be there when they take the screen down to confirm before the evidence is thrown away!

 

[Peter]

Builder said a wee bit of the mastic is starting to peel away so water getting into the tile perhaps? From memory they weren't a terribly good quality tile and were very sizey so maybe open to letting a bit of water through.

 

[Time's Ran Out]

water in the biscuit of the tiles at a guess-maybe sealant issue or some cheaper ceramic it maybe creeping in at the egdes?

Looks like foggy was right!
Well done foggy.