9mm ply

[Leatherface]

Backer board or No More Ply sheets are always good, if not expensive. At the risk of being shot down in flames here- I have found that 9mm ply is acceptable in a lot of cases - have used it myself and screwed down well. Good flexi adhesive, sometimes with latex admix, never had a problem.

 

[tilinga2z]

I tend to agree with leatherface have tiled at least a dozen floors on 9 mill with no probs as long as flexi is used. Remember hardi backer flexes and the results are largely the same just be mindfull to use a good bed of addy no scrimpin, yes is maybe not text book but will suffice. Forewarn customer but if he/she insists...........

 

[White Room]

With hardy you must allow 2/3mm between joints for movement

 

[Leatherface]

Again, Ditra matting is one of the most reliable things to use !!!

 

[Fekin]

I've known of a few floors done with 9mm ply, with right adhesives and prep they have been fine.