Concrete slab floor - which underlay is best for warmth with carpet

[volks]

I recently carpeted one room in my house and put down 10mm PU underlay and a low weave carpet. I've since found the floor can still feel quite cold in that room. Before I redo any other rooms, I wanted to find out which underlay is better or preferred.

Is PU not thermally efficient enough, or should I go thicker? Perhaps a better brand?

I looked at rubber waffle pattern underlay which might be warmer, but not sure how well it holds up for carpet support and crushing.

Any advice is most welcome, I want to ensure I get it right for the larger rooms and keep my heating bills down!

 

[crazydaze]

Have a look at Ulster Carpets Axfelt65 Natural Felt Crumb combo underlay, it's superb for an insulating and supportive feel over Concrete Subfloors.

Axminster offer the same product, Brintons do a version called Brinflet. Avoid felt combo underlays with Man Made Felt, they are'nt as insulating and are a similar price