Replace bathroom floor

[msmsm]

I have a bathroom I need to renovate. I had the pipework redone when the ceiling below was down but now I need to address th floor. It is currently very butchered original floorboards, with large holes where they have been removed and cut.

I can take out all the bathroom bits (bath, toilet etc) so have access to the whole floor. I am thinking of removing all the existing floorboards and replacing it with 20mm water resistant ply. Is this a suitable flooring? As we most things DIY, my experience in this area is very limited! Anything I should be careful with, other than ensuring joins lie along the joists? Should I deal the underside of the ply too?

Thanks!

 

[motorbiking]

Are you tiling on top? are you installing a new bathroom? Leave the floor boards in place and board over with an insulated tile backer board.