What is best for bathroom sub-floor?

[vrytir]

Hi guys,

I want to ask you what to use for sub-floor. Should I use marine plywood, exterior hardwood plywood (should I prime it?), MDF or chipboard?
What is the best in your opinion? Should I prime it, if so what to use?

Thanks

[Sir Ramic]

18mm - 22mm -25mm WBP ply.

[Sir Ramic]

Prime with SBR back and edges, not face.

[Muse2k8]

As above use as big a sheet as possible and get it fastened tight

[nybor62]

as above leave a slight joint between boards. dont butt edges together

[timeless john]

Whatever you choose cover it with a tile backerboard before tiling.

[Dave]

Yep. IMO 22mm ply with noggings at all board joints and then over boarded with hardibacker 250(6mm) for moisture stability...perfect substrate..

[Rich]

Bang on advice above. As thick a ply as possible after strengthening the floor and then over boarded with a cement board. The ply needs sealing underside and sides, 2mm joint left between the boards and the sheets staggered. Have a read through the link below for a little more info on over boarding


Plywood floors...

[swanman]

Yes good advise as usall

18MM TO 22 MM depending on height restrictions to the door screwed

Then 6/12mm cement board fixed

[vrytir]

Hi guys,

you are the treasure. I wil go for 18mm WBP and then 12mm Tile Mate backerboard. I choose this as the R-Value is 2.5 and I want to have underfloor heating. Do you agree with it? I hope you do

[Mike]

yes that's fine provided you can afford the extra height. the ufh will raise the height by a further 5mm or so too and ensure you cover the cables/matting with slc (self levelling) prior to tiling

[vrytir]

I will go for 18mm WBP plywood and 6mm tile mate backerboard as this is recommend for floors (12mm is not recommended as I previously wanted to use)

yes that's fine provided you can afford the extra height. the ufh will raise the height by a further 5mm or so too and ensure you cover the cables/matting with slc (self levelling) prior to tiling

I thought that I just lay underheating cables than use flexible adhesive to cover it and use this "cover" to tille straight on this.

When screwing backerboard to ply, do I screw in to the studs or is it O.K. just in to the plywood?

[whitebeam]

Screw just into the ply but make sure the ply is well fixed, I use Turbo screws from screwfix at 25mm for the backer board...

[Mike]

I will go for 18mm WBP plywood and 6mm tile mate backerboard as this is recommend for floors (12mm is not recommended as I previously wanted to use)

I thought that I just lay underheating cables than use flexible adhesive to cover it and use this "cover" to tille straight on this.

When screwing backerboard to ply, do I screw in to the studs or is it O.K. just in to the plywood?

if you use slc over the cables this will ensure the cables are fully covered and prevent any hotspots in the cable,it will also help prevent you damaging the cable whilst laying the tiles and it will give you a nice flat surface to tile onto.