Suitable substrate to redo bathroom boxing-in?

[adamwilde]

Hello there.

We're having our bathroom redone along with some internal building work, and unfortunately we chose poorly when deciding who should do it. The builder (who is also a neighbour) made a poor job of the boxing-in for the back-to-wall WC and semi-countertop basin. And an even worse job of the tiling.

So, we're having the frame of the boxing-in reclad by a joiner and the tiling redone by another friend who is a tiler we've used very happily before.

The original builder used MDF for the boxing in, which concerned us (as did so many other thins along the way, but you live and learn). The joiner we're engaging to redo the boxing-in has suggested (and now purchased) moisture resistant MDF as an alternative substrate.

However, after he bought it I read somewhere that (a) it's not up to the job in this situation and (b) you can't tile onto it.
Our (new) tiler did some research and suggested Aquapanel from Wickes, but that's not suitable for loadbearing, and we're unsure about increasing the height of the boxing in with multiple substrates.

The boxing-in is at the opposite end of the bath to the shower, so should not be directly made wet, other than by splashing around the sink.

The joiner's due to do the work on Thursday, so any advice would be very gratefully received, as we're some weeks into this project now, and still feeling rather out of our depth.

Here are some pictures of the boxing-in as it stands, in case they're helpful:

Many thanks for your help.

 

[adamwilde]

Sorry to ask again, but if 6mm ply isn't up to the task, what should the substrate be? (It's going onto a first-floor wooden floor by the way.)

 

[jay]

depends on flex but min 12mm at the least you could ask for a tiler on here to have a look if you like :8:

 

[ad tiling]

Thanks for your thoughts on this. I'm of the same mind, but we've precious little room in the bathroom (the door already hits the toilet as it is). Hmm. We might reconsider, though...

door hits the toilet i think building regs dont allow that 😳
plumber will know the distance between door and
toilet

 

[Colour Republic]

Sorry to ask again, but if 6mm ply isn't up to the task, what should the substrate be? (It's going onto a first-floor wooden floor by the way.)

Get your tiler to look at it and give you his opinion on what would be best to use in your situation (would need to see more pics to give you info here), any flex in your floor will mean the tiles debond or maybe the grout cracks and water will find its way under the tiles. Felxible adhesive 'flex' to a certain degree but only a minimal amout, if the floor is bouncing it will fail.

Having looked at the photos again, is it possible to raise the boxing 20-30mm so it is level with the window reveal? giving you clearance all the way around the basin. Or would this mean the basin is at an unsuitable height?