Best underlay for wood flooring? Vapour barrier needed?

[glock339]

Hi I'm going to be laying hard wood flooring over existing floor boards and I'm currently looking into how I can insulate the floor while I'm on.

It's a suspended timber floor and I was originally thinking of under floor insulation, but for various reasons this is defo not an option. Therefore the only other way forward is insulating above the floor boards I think. I've been reading up on underlay etc but the choices available are VAST! So with what I've read so far I was thinking:

Seal up all the gaps in the existing boards (not sure exactly what I'd be using)

Some kind of decent underlay. really haven't got a clue which one to choose as there is so many! Any ideas for best thermal insulation?

Some people say I need a vapour barrier over the top of these, some people seem to disagree. Should I put one in & which type is best?

Then put my new wood flooring on top of all off these?

Sorry about quality of this post but I'm trying to type it on my phone at wok while no one is looking!!!lol

Cheers!

 

[mointainwalker]

There is no magic product in the insulation field.

If you look at the dedicated insulation products used in housing they are 100 -200 mm thick. The primary purpose of your underlay is to protect the floor-covering and insulation is secondary: since this underlay is likely to be 3 mm - 6 m thick, it will only have a marginal effect on heat-loss, so don't spend extra money on some product that pushes its high insulation properties unless they are verified with U-values.

I would vote with the "no vapour-barrierites "

 

[glock339]

Thanks for that. Yeh I didn't think I'd get to much insulation from 6mm of underlay but have seen loads of different types making big claims etc. I suppose I should have thought of the obvious answer of looking at the U-values! I'll have another look tomorrow anyway and have a closer look at the U-values.

I did consider insulating on top of the floor but I'm really put off by the amount of height I'd lose from the room. Underneath my floors are a nightmare, only 6 inches depth beneath in some areas and to make matters I have had to pack out & level all the joists with lots of rows of breeze blocks (& DPC) as they were only 3 inch thick , oh and my joists dont even run in uniform lines & are completely all over the place!lol So under floor insulation is out.

I have read that I should seal out any drafts from underneath the floor to stop cold air. There's some pretty big gaps in some of my boards from where they've been lifted etc so I'm guessing I'll have to fill these somehow and then look at the smaller gaps in the boards and between the walls. I've seen tapes specially made for the smaller floorboard gaps, is this worth buying or will any tape do? Or I've also seen people tape the edges of certain types of underlay together and then fixing it tightly behind the skirting boards, any preference or both!lol

Cheers.