Micro-cement over wet room shower tray

[JMWilson]

Evening all,
Relatively new to the micro cement’s I’ve done a few bathrooms but whilst looking at one I’m starting in a couple of weeks, they’ve a impey wet room tray with a water guard wetroom
Floor membrane (1mm thick butyl rubber) over it……
So my question is can I go over the top of it with the usual procedure or does it need taking up?
Many thanks

 

[Stewie03]

As long as you don’t use standard plasterboard you should be sound ain’t that right @Retired Spread

 

[JMWilson]

It’s 18mm ply and a grp tray, but the builder wants to put a membrane over it as another barrier (1mm fleece lined rubber) and I’m wondering if I can go over the top?

 

[BobbyJack]

Did micro over an impey tray about 6 years ago. Used a product called feather it first on floor over tray and fibre backed rubber tape. Then micro over the feather it. Worked really well and still know the guy who I did it for and still no leaks and still looking good. The feather it is miles cheaper than micro so worked as a good sacrifice coat to start off with