Plywood Or Cement Board

[mike1979]

Trouble is some people think backer boards are the answer to the entire world and think the prep doesn't need to be done but it does get the bounce gone then the backer boards will reward you I have before now replaced a floor with wayrock and laid uncoupling on top job done

 

[Old Mod]

 

[AliGage]

@RayTheTiler - I'm curious how Ditra would solve deflection.....

@zed123 - How has the mezzanine been created? Are you able to view the underside from below? A chipboard floor spanning 600mm between joists will still have considerable bounce. You could get some noggins in from underneath.

Then over board with a suitable tile backer, glued and screwed.

 

[Lee@emctiles]

And to add to @AliGage comment i would probably use an s2 adhesive too, like TileMasters Ultimate.