Shower tray on expanding foam....???!!!!

[Showergirl]

Hi,

Can someone tell me please........should a 1600mm X 900mm stone resin shower tray be placed on expanding foam?

We have just discovered that the shower's been leaking since day 1 (installed 3 years ago) - the ply is rotten through underneath - you can push your hand through it.

Got plumber to come and look - he swore blind he "would never use expanding foam", and that he used tile adhesive. When he left, I pushed my hand through the rotten ceiling, directly underneath the shower tray to find........expandable foam! (liar!)

I would really appreciate someone telling me what he SHOULD have done (concrete and sand mix?) And is this something he should just know as standard practice?

Also, we really now need to remove the tray, so that we can replace the rotting floor (otherwise, every time we stand on it, it's gonna just sink into rotting wood, and break the sealant, thus more leakage), and bed it down properly. Is it risky removing the tray when it's on expanding foam? The last thing we need is for it to crack when we take it out.

Thanks in advance for any ideas/advice!

 

[petej]

I work on gas but from memory the last time I fitted a ceramic shower tray on a wood floor for my neighbour the instructions said screw down a sheet of marine ply to the floor boards then bed shower tray onto this using a weak sand and cement mix.
Can you slide an old wood saw into the gap and carefully cut through the expanding foam ?
watch out for any hidden wires or the water or waste pipes.
Pete

 

[Showergirl]

We could try that....we have another plumber coming tomorrow - on very good recommendation. He will hopefully tell us how to sort it; the wood underneath definately needs replacing though - it's rotten!

I knew it was meant to be on sand and cement - the plumbers apparently should do this as standard practice - like wiring a plug correctly.....!

 

[cham44]

In CA they mostly use the hot mop method.