Shower tray fitting on wood decking

[G and J]

2 hours ago, Nickfromwales said:

Ok, so you may want to go for 12mm plywood everywhere else upstairs, and drop back to 6mm at the threshold of the bathroom doorway. That'll allow you the 'good job of it' plywood layer, and then a 6mm deficit for you to install a mat and some electric heating mat, submerged in SLC (use Mapei LINK as it has fibres), and then your LVT will be flush from the hallways to the bathroom floor.

 

Everything needs priming, expect @Pocster, he's already primed to the hilt. 

 

Brush some primer / water solution over the floor and UFH immediately before mixing the SLC, as you need to lay 'wet on wet' here for success.

 

Add 1/4 pint of water to the SLC right before you throw it onto the floor, after you mix it to their instructions. 

Oh well, if I should have allowed for 12mm ply throughout upstairs then I need to add another line on the “I screwed up” list.  Ho humm.  
 

But our stairs are in and the levels are set for 9mm total floor covering depth - 6mm ply plus ~3mm of LVT.  We’ve no thresholds between rooms as we want a continuous floor treatment throughout.  So the electric matting goes onto the chipboard, with the levelling compound.  We’ve been recommended a local flooring company who are happy to apply the levelling compound on the UFH mats I install. 
 

I’ll be putting the shower trays direct onto the chipboard as I’d rather not see a line of ply under them.  Perhaps my next step is to test fit the trays and see how flat, stable and level they are, and then take it from there. 

[Nickfromwales]

1 hour ago, G and J said:

Oh well, if I should have allowed for 12mm ply throughout upstairs then I need to add another line on the “I screwed up” list.  Ho humm.  
 

Another one for the free 1hr chat I offered you, lol. You are a tough cookie to crack....aka stubborn.  Same here.

[Nickfromwales]

9 hours ago, G and J said:

Oh well, if I should have allowed for 12mm ply throughout upstairs then I need to add another line on the “I screwed up” list.  Ho humm.  
 

But our stairs are in and the levels are set for 9mm total floor covering depth - 6mm ply plus ~3mm of LVT.  We’ve no thresholds between rooms as we want a continuous floor treatment throughout.  So the electric matting goes onto the chipboard, with the levelling compound.  We’ve been recommended a local flooring company who are happy to apply the levelling compound on the UFH mats I install. 
 

I’ll be putting the shower trays direct onto the chipboard as I’d rather not see a line of ply under them.  Perhaps my next step is to test fit the trays and see how flat, stable and level they are, and then take it from there. 

You won’t see the ply as the rest of the floor covering comes up way higher than that.

 

You’re very brave putting SLC straight down onto the chipboard, but if someone says they’ll warranty the job without even a 3.6mm (aka 4mm) ply binder then it’s on their head I guess.

 

I’ve never laid anything directly onto particle boards, ever, but I have had lots of insurance work from others who did so.