tiling bathroom floor help

[paul777]

hello
I`m tiling my bathroom floor which has the old flooring boards
am I right in saying I need to screw down 9mm ply to the old boards
then seal ply then ok to tile ?
9mm ok or thicker ?
thank you paul

[wine~o]

Depends on how solid the existing floor is, if there is any movement then a thicker ply might be necessary..

Try a full glass of water, put it on the floor and walk around it. if it spills you've got movement and need to sort that out..

EDIT... oh yes and seal it, the adhesive will tell you what primer you need.

[royaloakcarpentry]

15mm ply is the minimum for over boarding before tiling.