Garage Conversion - what flooring to use for tiling onto?

[JonnyS]

Hi,

We're in the process of converting our garage into a kitchen/dining room. The back of the space was originally a separate utility room and we've knocked though. The floor in the garage has has a damproof course, insulation and joists. The utility room has a concrete floor.

I'm wondering what is the best product to lay on the joists in order to tile on top of the whole lot? I've read some things saying P5 chipboard/caberfloor is fine, whilst others saying you need to use 22mm marine ply wood. I also read something about needing to have an expansion joist between to concrete flooring at the back and the rest of the space.

Any help/advice would be much appreciated, thanks.

 

[Qwerty]

Using ply or caberflooring is just fine, but this is better.....

James Hardie - HardieFloor - https://www.jameshardie.co.uk/product/hardiefloor/

You will have to bring up the level of the solid floor to match the new suspended floor using self levelling compound.

Best practice would be to lay a decoupling membrane over the whole floor with an expansion joint spanning the entire length of the divide between different surfaces.

What tiles are you laying?

 

[JonnyS]

Ok thanks for that.

I'm not sure on what tiles we'll be laying yet. We basically have OSB board on the joists at the moment, but the joiner is coming in this week to lift them and drop the height of the joists, so when the board goes back down the height is level with the concrete floor at the back.
The joiner suggested putting caber floor/P5 chipboard down rather than the OSB board, suggesting that would be much better for the tiler to work with once they come - which will be later down the line.

So the decoupling membrane goes over the top of everything?

Regards the expansion joint, does this also go on top? Or do I need to have a conversation with the joiner about this before he drops the floor?

 

[Qwerty]

Schluter have an excellent section dedicated to explaining movement joints....

Movement Joints | Schlüter-Systems - http://www.schluter.co.uk/movement-joints_3.aspx

Basically, the movement joint will need to run through all layers. Below is a diagram showing this...

 

[JonnyS]

Thank you again, incredibly helpful!