Marmox or No more ply on floorboards

[webrits]

Hi,

I'm doing a complete refurb on my bathroom and was wondering about boarding the floor prior to tiling.
Floor is currently floorboards and is a little uneven. I'm also considering electric UFH but want to minimise any increase in floor height.
So... would 6mm Marmox multiboard be OK, fitted on a thin bed of adhesive, followed by UFH then tile? Or would I be better with a cement board like NMP?

Appreciate any help.

Thanks
Paul

 

[Mr Chibs]

From memory, I did a really think plywood to flat it off, then I used flexible self levelling compound with fibres in (Mapei) to level it all up.
Only problem with Marmox type boards at 6mm, they don't take lots of weight if you stand on them.

How much space have you got to play with?

 

[JaimieH]

Marmox and other construction boards have to be 10mm min when going over floorboards but this would give the best insulation under your UFH. You could use No More Ply or Hardibacker if height build up is critical but you would compromise the warm up time of the UFH. Whichever option you choose I'd definitely recommend a levelling compound prior to tiling. This will totally encapsulate the heating elements and prevent and air pockets which can lead to localised overheating and damage of the wires. Also you'll prevent damaging the wires when trowelling your adhesive. Don't use plywood under the tiles.

 

[webrits]

Thanks both.
In terms of how much I have to play with, I guess I just want as small a step as possible when walking in from the landing.
Maybe I'll go with NMP and live with a slower warm up time...