Q: What is the best way to rebate an acrylic shower tray into the Durapanel wall?

Rebates into the panel can be precut in the factory using CNC technology. Rebate should be 40mm higher that the upstand so a 40×10 H3 timber bead with silicone can be inserted hard down on top of tray upstand to protect the panel. Also it is best to apply primer (ideally waterproof material) over the cut Durapanel board. The shower lining will then come down over the tray upstand.