Hardi 12mm on joists?

[bctiling]

Hi, does anyone know if 12mm Hardie board can be used straight onto sound floor joists?

 

[Ian]

No mate, hardie is only a suitable surface to tile to, it offers no structural strength. Chipboard/ply over the joists then, glue and screw hardie ontop.

 

[bctiling]

Thanks,i guessed that would be the case. Got tile a kitchen floor that has floorboards running through to the hallway and they dont want a step. 400x400 porcelain tiles. The boards are 18mm,i guess theres not mch choice. Is 12mm ply enough,ive had different opinions on this?

 

[Time's Ran Out]

12mm plywood onto joists and tiled! No.

 

[bctiling]

A step it is then🙂

 

[peteablard]

It needs to be 15mm minimum but ideally 18mm.