Underfloor heating prep question

[silver50]

Hi, I was planning to lay 12mm ply over old boards and then an insulation layer (prior to underfloor heat element) and then a latex screed before tiling.

My question is mainly what to use for insulation, but I am wondering if my plans are overkill. Just a small/med size bathroom.

Anyone know if the cement tile backer boards (6mm) are decent for insulation? If not, what is thin but good to insulate (don't want floor level rising too much)? I presume you screw the cement tile backer down too? I do like the idea of screed to level the floor nicely and quite like the idea of it protecting the heat elements while tiling but maybe I should just put the heat elements on the ply and screed over the ply?

Sorry if this sounds a bit confusing but I feel a bit confused as to whats best!

Edit: The likes of this sounds fine for some thin insulation but I don't think it's something to be tiling/screeding over hence my question re tile backer board.
https://victoriaplum.com/product/wa...VTLHtCh2nWwpEEAYYASABEgIye_D_BwE&gclsrc=aw.ds

 

[ericmark]

When mine was laid, ground floor, first a massive hole was cut all original concrete floor removed, since wetroom drains laid first, then about 6 inches of polystyrene, then plywood, then heating wires, then shower tray then the tiles, so around 9" of new floor.

Result the floor is never what you would call cold, even with heating off, and when on lovely and warm, however it will not heat the room on it's own, any warmer could not walk on floor, but without towel rail on the wetroom is cold.

Son fitted wet underfloor heating up stairs, insulation fitted to deaden sound, but not really worried as to what heat goes down, whole idea of underfloor heating is to cool the side boiler of the rayburn cooker, again still has radiators in the room underfloor heating is an addition.

 

[silver50]

Thanks for your reply. I certainly need to try and keep my floor level height as low as poss. It’s an old upper flat with floorboards and joists. I definitely need ply which I’ve got cut today. I’ve found some ideal 6mm thick tile board come insulation today so I’ll lay this on my ply. Then of course the heating elements and screed.