Limestone floor with ufh

[IanB]

Hi all,
Following on from my post the other day. changing a bedroom into a wetroom in an old house.
25mm wooden floorboards in good condition, nice and firm and level, haven`t been lifted at all and no flex in the floor.
Floor area approx 3.5 x 2.5 square metres.
The plan is to put a Maxxus 1400 x 900 rigid wet deck former in the corner and to lay 600 x 400 limestone on the floor with electric ufh.
What would you advise for the floor, Wedi/Marmox boards or a decoupling mat? Just wondering which would be the best way to proceed?

Cheers,

Ian.

[timeless john]

Decoupling mat every time, over a substantial underlay of plywood.

[Marble Life Ltd]

Is the floor still going to have no movement with another 3-400 KGs of weight on it?

Kev
Marble Life Ltd

[IanB]

Decoupling mat every time, over a substantial underlay of plywood.

What would be better, to replace the existing floorboards, with 25mm ply and noggins or to overlay the boards with 18mm (?) ply then decoupling mat?