Floorboards or ply under hardibacker

[helix]

hi there,

I'm not sure whether to remove the floorboards in my bathroom, and put down ply before the hardibacker.

The floorboards are in fairly good condition by arn't exactly a flat surface. They have been cut, pulled up and put down again a few times over the years (old victorian house).

Would it be advisable to remove floorboards and put down ply instead? If so, do I need to use marine ply? Not sure if normal ply would be ok because there will be hardibacker on top?

Are there any better solutions?

Thanks,
Alex

[david campbell]

you could remove the floor boards and replace with 25mm marine ply or 18mm ply then the 6mm cement boards,but would defo go with the idea of removing the floor boards if they are really un-even

[helix]

Thanks.

Would WBP ply be ok, or does it have to be Marine ply?

Just to confirm, If I put the hardibacker on top of 18mm, the ply can be just normal ply?

Is tiling directly onto ply ok?

[wetdec]

If you strip the floor put down 18/22/25mm ply and screw it at 300 centres there is no need for cement board....................

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[helix]

If you strip the floor put down 18/22/25mm ply and screw it at 300 centres there is no need for cement board....................
..

this sounds like the best and simplest solution. I can get 25mm WBP ply and tile directly onto it.
Also sorts issue in my other thread about the shower tray instructions stating I should cement tray to ply
And strengthens floor more than just tatty floor boards and hardibacker.

[wetdec]

You will need to uncouple it and tank it obviously (what tanking method you thinking of m8 )


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[helix]

You will need to uncouple it and tank it obviously (what tanking method you thinking of m8 )
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Didn't realise this

It's not a wet room, just a standard bathroom.

What should I do?

[wetdec]

If you lay an uncoupling membrane before your tiles it will prevent cracking of the tiles due to latteral expansion and contraction of the wood. Ditra and Dura-CI are both suitable uncoupling membranes




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[helix]

If you lay an uncoupling membrane before your tiles it will prevent cracking of the tiles due to latteral expansion and contraction of the wood. Ditra and Dura-CI are both suitable uncoupling membranes

.

thanks

is this necessary on a 3 x 3 metre room?

[helix]

Having 25mm WBP ply delivered tomorrow with 4x2 for noggins.

Joists are 7x2.

What are the best screws to:

1. fix ply to joists / noggins
2. fix noggins to joists?

Also, do I really need to use uncoupling membrane? I'm using flexible BAL single part adhesive, and flexible grout.

thanks,
Alex