cocrete flloor question

[dada]

i am about to put in a concrete fllor for my new conservatory. so, its hardcore, 2 in sand, insulation, 4 in concrete.
the visqueen normally goes on top of the sand, but i was wondering if the celotex (like kingspan) insulation will be effected by the water when i poor concrete on it.
is it necessary to put another layer of visqueen on top of the insulation before the concrete as well?
thanks

 

[^woody^]

It wont be affected. Do it as planned, no need for an extra polythene layer