Insulation Recommendation for under Hardwood Floor

air

Hi all,
I'm ready to lay some solid oak flooring in my living room. I'm replacing carpet in a house that is seven years old. The floor is clean,level and fully dried out. Based on advice in another thread I am going with 18mm battens (these were the minimum advised as possible for secret nailing).
I'm just wondering what is the best material to use to insulate the space between the battens?
I'm planning on putting them at around 300mm centres but could adjust this slightly to suit rolls of insulation if required.
My priorities are insulation quality, environmental friendliness,cost and accessibilty to the product.

The room is about 18 square metres if that makes any difference.
Thanks in advance for any recommendations.

Viking House

Hi Air

I would go for Softboard or Rockwool.

Viking

air

Hi Viking, thanks for that.
Could you recommend a supplier for Softboard?

Viking House

I have 35mm softboard in my lock-up in Dublin, I imported it from Poland.
It cost me about €10/m2 inc transport.
If you built a floating floor on top of softboard and glued the flooring together you wouldn't need to nail it.
It would be a lot quieter also.

air

Hi Viking, that sounds good but as I'm retro fitting the floor into an existing room that has a normal floor level I'm trying to keep it down as much as possible.
If I laid the 35mm stuff & put the 18mm oak on top I'd be left with quite a step from the hall into the room.

Viking House

Hi Air

8mm or 12mm softboard should be available in Limerick from some of the main suppliers.

air

Thanks Viking, I'll check them out at the weekend.
You've got me thinking re laying directly onto softboard though, how does it compare to laying on battens?
If I laid directly on 8mm softboard it would keep my floor level quite low & I'm sure 8mm of softboard would still provide better insulation than the carpet ever did.