Bathroom floor thickness?

[CrawfW]

Hi,

How thick should the marine ply be on a bathroom floor fixed at 400mm centres? I was thinking that 25mm would be more than enough......

However, a wet-room supplier tells me i will need also 6mm cement board on top of this too to prevent bending.

This seems excessive to me. We only had 18mm floorboards originally.

Comments appreciated

Crawf

P.S - For what it's worth, we are going to be using venetian plaster as the decorative finish.

 

[KenGMac]

CrawfW, Hi.

In all honesty, you may not have any option, in so much that if you disagree with your preferred builder / installer and instruct him to do other than that He is suggesting, any Guarantees he may promise going forward, could be negated if you insist on a different Specification to that which your Contractor is suggesting / offering

Ken.