Advice please :-)

[bobbin]

Going to be doing my parents bathroom in travertine as soon as my new dewalt d24000 turns up but just want to check something with you guys.
Floors coming up to expose joists. Then I intend to use 18mm marine ply, then warmup boards, then loose wire warmup ufh and then screed prior to tiling.
My question is will I need to use a decoupling membrane straight on the ply before the warmup boards or will I not need it?
Cheers all ;-)

 

[White Room]

I'd be using a thicker ply, 22mm thick with perhaps extra noggins but would'nt worry about warm up boards on ply...matting to floor, slc then decoupler.

Just make sure theres no bounce/deflection on the joists.

 

[bobbin]

Cheers mate.
Warmup mats not needed then, result, saves a bit!
Not using the matting going with loose wire system instead. Will the coupling reduce the heat to the tiles at all?
Will go with 22mm if I remove the warmup mats

 

[White Room]

Ply can be warm anyway, screed can be different issue...the heat will transfer thru the ditra, done loads like that..

Remember to not turn on the heat for atleast a couple of weeks and only a few degrees a day.

 

[bobbin]

Cheers pal, I'll go with your way then, ta

 

[doug boardley]

I'd go with 6mm insulation mats on the ply (22mm), then loose wire, then slc, then ditra, and finally the trav

 

[bobbin]

So it's only the mats that are dubious then. I was told they would make the heating far more efficient.
I'll check with the olds and if they are still happy to keep the mats I will keep them in but will also do the rest as described.
Thanks for your help guys.