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

 

[crazydaze]

Thicker fibreboards will insulate well, but thinner, denser 3-4mm stuff like Duralay Duratex can be better for sound absorption.

 

[Doggit]

I'm using 6mm fibreboard at the minute with an engineered flooring, and the floors warmer than the rooms that have solid wood glued to the concrete - and it's a north facing room with 2 outside walls as well. We originally started off with porcelain tiles on top of XPS insulation boards, but the tiles were crap so we ripped them up and went for the wood. I'd have used the XPS boards again, but would have needed to buy more, whereas I had enough fibreboards for the job.

With the job you've already done on the floor, I suspect you only need something that's going to stop any odd draughts coming up. You can't tape fibreboards together, so look for something that has tapeable joints