Question on flexing of shower tray

[barkerben]

Hi,
I have just had a new bathroom fitted. It includes a quadrant shower tray that would be hard to replace as it is of non-standard dimensions. The tray is acrylic capped with a GRP structure. The tray sits on a pedestal covering pipes, and is constructed from 18mm MDF.

The pedestal had a rebate around the edge such that the tray sat nicely on top. However, because the base slopes in two dimensions, there was a gap of varying height between the pedestal top and the tray itself. I beleive the plumber then placed some spadefuls of mortar on the pedestal and finally placed the tray on top. The whole lot is now quite embedded by tiles, shower enclosure etc.

I used the shower enclosure for the first time yesterday. I noticed that in a number of areas in the shower, if a foot is placed, it is possible to feel the tray flexing down a cm or so until it hits something, presumably a lump of mortar. I am concerned that this flecing may limit the life of the tray, which would be very tricky to replace due to its non-standard size.

I had assumed that the entire tray had been filled with mortar by placing the tray upside down, putting a cardbiard coffer dam around the drain, filling to the brim with mortar, placing the pedestal on top, waiting to dry and then putting right way up. This seemed the most obvious way, and would have ensured no give in the base.

My question is how much of a problem this flex is likely to be. If the shower life is limited due to the flex, then I am stuffed as it is almost impossible to replace. However, I suspect that to remove the tray would be quite a lot of work - some tiles would need removign and replacing etc.

My Plumber is really nice, and I would feel bad about trying to get him to fix it if I was not justified in my worry. However, if it needs fixing it needs fixing...Any thoughts before I talk to him?

Cheers,

Ben