The Best Boards for a Floating Floor?

[PatsPatter]

I'm seeing quite a lot of quite strong opinions regarding the possibly less-than-usefulness of chipboard as the top surface for a floating floor.
I'm just at the stage of ordering the flooring I'm going to use and want to find the best option.
It's a new-build sun room, cavity wall, very well insulated, DPM under concrete sub-floor, no heating in the floor, not heavily trafficked, and has 100mm of PIR down to bring it up to the level of the existing - assuming I put 22mm of whatever on top of the PIR
The jury (wife) is still out as to what surface covering (carpet/wood/engineered wood) gets used as the final finish across the existing and new, all at the same level.
What's the best/reasonable price option?
Will

 

[Doggit]

18mm chipboard with an underlay, and then a wood floor on top would work fine, but carpet would allow it to flex, so you'd want something like fermacel that will glue the adjoining board far better.

 

[PatsPatter]

18mm chipboard with an underlay, and then a wood floor on top would work fine, but carpet would allow it to flex, so you'd want something like fermacel that will glue the adjoining board far better.

Apologies for the question, but I'm not quite sure what you mean regarding the Fermacell gluing the adjoining boards.
Is this how would the layers go? From the bottom up:
DPM - already there
Concrete - already there
PIR - bought but not laid yet
Underlay - what type?
Chipboard - 18mm, I assume, acceptable if the final finish is T&G wood
or ,if it's going to be carpet:
One of the Fermacells - but not sure which one you mean. I have approx 120mm available above the afore-mentioned concrete screed, 100mm taken by the existing (as in 'I've bought it') PIR, then the previously planned chipboard, taking me to a few mm above the existing adjoining concrete floor, which was/is going to get a coat of Self Levelling Compound. It needs a bit of SLC to take out the slightly uneven finish on part of it, anyway.
Final floor finish

[Building Inspector was dropping hints about gluing the edges of any chipboard using polyurethane (Gorilla-type) glue, which I'd already thought would be a good idea for stability, in any case.]
Will

 

[Doggit]

It would be DPM, Concrete, PIR, Chipboard, 3mm foam underlay, wood floor.

And yes, you'd glue the joints, but chipboard doesn't have a very large joint, so not quite so good for carpet that doesn't give any supporting rigidity. The Fermacel boards have a much larger overlap, so when glued, would make a much more rigid layer for carpet.

 

[PatsPatter]

It would be DPM, Concrete, PIR, Chipboard, 3mm foam underlay, wood floor.

And yes, you'd glue the joints, but chipboard doesn't have a very large joint, so not quite so good for carpet that doesn't give any supporting rigidity. The Fermacel boards have a much larger overlap, so when glued, would make a much more rigid layer for carpet.

Got it.
I can see from the link you sent that some of the systems have about four or five times the overlap area.
Many thanks.
Will

 

[chappers]

shouldn't matter, if glued properly, you won't break the joint in chipboard flooring without destroying it.