Corner (vertical) flashing, whether internal or external, rises to the higher of 1 800 mm over the shower floor finish (or over the bath or tray base) and 50 mm over the rose. The external kind suits external membranes set behind sheeting or render if its legs let the lining overlap by at least 30 mm, and sheet fixings must not pierce it. The internal kind suits either membrane type if each leg overlaps the lining by at least 40 mm and, with internal membranes, rises from within the shower tray; with external membranes, overlaps the top of the floor waterproofing by at least 20 mm; with preformed bases or baths, runs down to the lower edge of the lining.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.