raising a utility floor level - best way Ply or screed

[etaf]

i'm renovating out a utility room approx 2.6x5.8m

Designed it all now, based on raising the floor level.

i want to come up 67mm to bring the floor level with the other room via a door way

will be using vinyl flooring covering in the room

floor currently is a concrete base

I will be adding radiators, worktop with sink, a number of IKEA cabinets , fridge freezer, washing machine, tumble dryer, combi boiler.

The pipework will just be on oneside of the room, so will not be going across the room - the hot and cold pipes are already sunk into the existing floor to go across the room

I had planned and costed out (1) - so a 2440 board will go across the 2.6 wide room and leave a gap - for pipework and cable - which i will then cover as required - Mostly under the 2.8 worktop/white goods and cabinets - so mostly out of site

BUT was suggested I would be better to screed - your suggestions

1) using some 60mm celotex (giving some insulation) , then 3.5mm plywood and then 4mm vinyl
which will be easy to do

the 2440 will be fine , happy to have a gap/channel along 1 side , as i can use that for pipes/cables and then cover as necessary

BUT how to fix to stop any movement or also what tape to use to seal the joins to stop any issues of splitting the vinyl with any movement if the plywood moves at all

2) use a tile backboard like jackoboard

and then screed over the top of that with something like fibre-reinforced Mapie from screwfix OR the F ball screed I have had both used , the F Ball over some floor tiles in conservatory and maps in a cloakroom

OR other suggestions

[dewaltdisney]

I think that the Celotex base is the best way to go, T&G chipboard flooring panels might be better for the flooring over the Celotex. You can glue the sections and form a single deck but leave a small gap around the edges to allow for expansion and it will work well.

DWD

[etaf]

Thankyou
great idea - just looking at using 40mm celotec and then 22mm flooring chipboard P5 water resistant,
62 mm - with 4mm ish vinyl
66mm which works out fine

thats a much better solution and pretty much what we have all over the bungalow - concrete floor with Polystyrene and chipboard , then carpet in all rooms but the dining which is wood flooring and thats what goes into the utility