Celotex on the floor

[SaudisLoveAudis]

Hi All,
I hope you are doing well.
I have about 32mm space before I have to cut the doors. I have 8mm laminate floor ready but I want to lay some Celotex.
The concrete floor has a DPM already so I can put Celotex straight on top of it.
Initially I though about putting 15mm Celotex so I can fit everything under that 32mm limit but then I changed my mind to increase to 25 or even 30mm of Celotex then I cut the doors.
On top of Celotex should I use 5mm wood fibre boards or a layer of so called QuickStep?

By the way why the price of Celotex can vary so much between the online shops?
Please advise.
Best regards

 

[SaudisLoveAudis]

I checked on another thread and it looks like in my case it's not a good idea.
Someone said that 50mm Celotex is the minimum so together with a required plywood, fibreboard and laminate would end up 83mm.
I don't have enough space under the front door so I cannot put it in there. This would require too many modifications.
I think I just use QuickStep and put laminate on top.