How to get the wooden sub floor level?

[Timmo]

Hi guys,

The room is an "L" shape. Horizontal part of L is approx. 1600mm long by 900mm wide where the floor former and shower area is to go. The vertical part of the L is approx. 1200mm wide (but only on the floor, one of the walls angles away) and 3200mm long and is outside the wet area. It will be screened from the shower area with an access in the corner.

I'm in the process of preparing the floor of an ensuite. I have a wetroom floor former which is 1200mx900mm and 20mm thick. I've prepared the former area using 18mm ply so that the 18mm ply sits flush with the joists ready to accept the former.

What I'm slightly unsure of is how I prepare the rest of the floor area outside the former area to get a complete level floor finish. The existing floor is 18mm T&G chipboard. I'm aware that I shouldn't tile on top of this and need to prepare a more suitable flooring. I understand the options are:

• Screw ply on top (12mm?)
• Take up the existing floor and replace with ply.

Either of these options result in a height difference between the wet room floor former and the rest of the floor.
So, what do people do to overcome this?
Are there any other options?

Many thanks.

 

[David - Tradetiler]

No question, I'd go with taking up the existing floor an replace with ply (of minimum 18mm) as that leaves you under height why not add some more ply underneath that or make up the distance with timber battens following the joists.

 

[Ceramico tiling]

If the chipboard is solid and you can get away with 12mm on top of it, then Hardy backer is a good option. If you go for the re-fit in 18mm ply then don't forget tilers do have some play with adhesive build up and SLC ( at least 10mm,but I use more sometimes) some tiling adhesives are better at this so just find out which ones for your tiler to use. If you use Ditra matting( which is recommended on any plywood floor) that will add about another 4/5mm to the level.

 

[DHTiling]

Finish the wetroom former 8mm above the chipboard or ply subfloor.. this will then allow you to overboard the rest of the subfloor in hrdibacker... then you can membrane tank over the whole floor area to waterproof..along with wall tanking to suit..

The 8mm will allow for adhesive under the hardibacker..