Preparing for slate floor [on wooden floor]

[quatro]

I would like a slate floor in my kitchen which is currently chipboarded [22mm]. Some has to be removed due to water damage so I thinking of replacing the whole floor to a more stable flooring - thinking of WBPly.

Then have been advised a good base for tiles is the 'hardback' sheets available in tiling shops.

If I use this would 18mm WBP be ok, with the 10mm 'hardback' on top, or would I have to use 22mm WBP?

{im assuming WBPly is more rigid than chipboard would be and I would be screwing it down onto the joists every 20-30cm - would that be ok?]

Also, what sort of insulation if at all could be put under the floor or would it interfere with airflow provided by the airbricks]

All advice appreciated......

 

[Jasonb]

Being natural stone you need a stronger floor than for ceramic/porcelain tiles.

Ripping up the chipbooard is the best way to go. You can then either replace with 25mm WBP ply and tile straight onto that or use 18mm WBP ply with either hardibacker or Aquapanel stuck to it using a powdered flexible tile adhesive but this will give a slightly higher floor level and cost more for little extra benifit.

The "thermal" tile backer/underlay boards provide very little insulation so are not really worth bothering with on a suspended floor. If you want to insulate then fitting say 50mm Celotex/Kingspan between the joists will work well, if the insulation is kept level with the top of the joists it will not affect the air flow.

Jason

 

[quatro]

Thanks jasonb for a very helpful reply