In my flat I've got this stuff called ISOMASS which is a rubber layer on top of flooring with a gap underneath. I can't just lay laminate or anything on the rubber. You reckon fitting 5.5mm plywood to bathroom would work ok?
I just don't know how to secure/fix the plywood on to this rubber stuff
Apply the finish floor surface on top of Impact Mat given due regard for the following. Carpets, Timber laminate panels and vinyl coverings can be placed directly over the Impact Mat 100 with an appropriate interlayer (as selected by the flooring contractor). All mechanical penetrations through the Impact Mat should be avoided e.g. A finished solid timber floor would commonly be pinned to a min. 12mm plywood interlayer.