I have a recurrent problem with a shower cubicle I inherited with the house.
It is poorly installed, such that I've been getting leaks through the toilet ceiling below when water runs down the tiles at the back of the cubicle (about a cup or 2's worth).
We first resealed around the bottom (where tray joins 1st layer of tiles) - problem remained.
Then we noticed some grouting cracks in first few layers of tiles - and there is a very hollow sound when these are tapped (compared to rest of tiles) & there is some movement when pushed gently.
So have re-grouted & this seemed to cure it for a while.
However a 2 person shower soon found the weakness out again & it leaked again.
Noticed an obvious crack, with play in adjacent tile - so regrouted this & shower tonight was OK (even with fair bit of water running down the tiles).
Is there anything else further we can do to minimize this happening again e.g. further grouting or silicon sealing over the grouting.
I don't really care if it looks a bit messy afterwards as I will probably replace the bathroom eventually - just want to avoid having to completely strip out the tiles, re-seat the tray etc. (££££).