Flooring underlay question

happyhero

Hi I laid and engineered Oak floor in my bedroom and was told by the shop which underlay to have. They recommended this 3mm stuff. I couldn’t believe how thin it was after only having laid laminate before and putting these green sheets that were 7mm under that, but anyway I did as instructed by the shop and it seems fine.


I am now wanting to lay the same floor downstairs and we have always had a problem with cold downstairs from under the floor. As I had gutted the room I decided to sort it out once and for all so I put Celotex (60mm) between the joists resting on roof battens and then put the floor boards back on top and then 12mm ply. Yes I know maybe too much overkill but we have suffered too long with it being freezing downstairs and I tried all the tricks of putting stuff in the gaps on the floorboards etc but ultimately the floor would become very cold in the winter with it being a wooded suspended floor with airbricks on 3 sides of the house (it’s a semi). My wife and kids would all end up with their legs on the sofa under a blanket at the coldest times.


Now I am looking at what underlay to get for this floor and thinking maybe I can get one to try and increase the warmth of the room (I have upgraded the heating in this room with a stove too) but I see although the thickness for many of the underlays are about 3 – 4mm they can vary greatly in price, can anybody guide me on this stuff please?


What should I go for, is there a really popular make suits all, will it not make much difference anyway, what do you think I should use and why?


Any help/advice appreciated