Sub layer make-up for vinyl floor

[ridpath77]

Hi there,

I need to build up a new sub-layer for a new vinyl floor in my bathroom. At the moment, there is hardboard (which has got water damaged) sitting on top of Celotex blocks (appears to be dense insulation foam).

My builder has advised that I could put down water resistant 18mm chipboard tongue and groove, then 5mm hardboard on which to lay the vinyl. Is this the best option bearing in mind they will be on top of Celotex blocks?

Thanks very much.

 

[Jadele]

I think I would go for the chipboard as suggested and glued together. Then overlay it with 5mm marine plywood. Stay away from hardboard as it will swell and destroy the floor if any water gets to it.