Slate tiling

[Lee222]

Hello everybody, newbie here. I'm about to do my bathroom and I'm a chippy not a tiler but handy enough and have done a couple in my time. I want to lay 10mm callibrated slate on the floor and walls. The walls will be aquapanel. In order not to gain too much height I've removed the existing boards and have laid 12mm WBP onto which will go a 10mm insulated tile backer board before laying a heating mat and then tiles. Problem is, though not properly fixed yet, the floor seems bouncier than I thought it would be. So how rigid are tile backers? Will they offer more support (never seen one) and if so which is a good one to use. Or should I beef it up a bit (nomoreply maybe?)
Also as not a tiler was going to use a self-leveling compound over mat so I don't nick cables etc when applying adhesive. But someone said to use a coat of adhesive instead as this is more flexible than slc. Sound like a good idea?
And finally, which adhesive and grout would people recommend? (oh and sealer, pref satin)
Many thanks.

 

[david campbell]

if you have removed the existing flooring you should have added extra noggins and at least 25mm wbp,this would take the bounce out of the floor
12mm isn't really going to stop the bounce in the floor mate

 

[Lee222]

Thought I was pushing it a bit! Can put in more noggins, then maybe lay another 12mm running the other way. Any other helpful tips much appreciated.

 

[david campbell]

Thought I was pushing it a bit! Can put in more noggins, then maybe lay another 12mm running the other way. Any other helpful tips much appreciated.

not too sure about that in theory it still gives you the inch ply but the 25mm is also to do with the moisture resistance!
i'e drying out of the adhesive

 

[Lee222]

But the adhesive will be on the 10mm tile backer not the ply.

 

[david campbell]

that should be ok then as long as there is no movement in the floor