I have encountered a problem. My shower tray was leaking and I found out it was because the tray was flexing and causing a gap at the seal. I thought this would be an easy fix and have taken the seal off. Turns out this is not the case as the gap between the seal and the tiles is about 1cm tall. And also quite deep. I was thinking I could either grout the gap and then seal it or even expanding foam and then seal? I'm just worried this won't be a decent/permanent fix. What are your thoughts?