I am planning to replace a leaky shower tray. It is in an alcove whose
walls are made from "Paramount" type partitions (i.e. a cardboard
honeycomb sandwiched between two sheets of plasterboard).
The alcove is 74 cm wide. The existing shower tray is about 78cm wide
and is mounted on a riser kit in such a way that the top of the tray
is about 26cm from the floor.
In order to accommodate the tray, an 11cm tall section of the sheet of
plasterboard was cut away on all three sides of the alcove (so in that
"slot" area, the wall consists of just the cardboard honeycomb and the
rear plasterboard face). The cut-away section starts at 19cm from the
floor and stops at 30cm from the floor.
I suppose the easiest thing to do would be to put in a new shower tray
at the same height. However, it would look neater if the tray could be
lower. As far as the waste pipe is concerned, that would be fine as
the waste runs at a height of a couple of cm above the (chipboard)
floor for 40 cm or so before disappearing under floor. Can anyone
recommend a way of patching the Paramount board so that the new tray
can be set lower than the old one?