We have a Merlyn blackbox offset shower 10000 x 800 on a merlyn acrylic shower tray. All fitted sealed, sealed in etc about 18 months ago.
Tray is on legs for plumbing reasons.
Floor(some sort of sheeting)under shower tray feet is distorting under the weight. Joists are fine.
Shower tray legs are adjustable for height would be capable of taking a sheet of something up to 20mm thick under them. Would be very difficult to screw anything well down to the joists given the restricted space though.
Any recommendations not involving taking the whole lot out?
TIA for any replies.