What's the warmest underlay for carpets and cushioned floors? Are insulation boards/tiles suitable as a base with underlay and carpet on top? Can carpet grippers be fitted on top of insulation boards?

Hi ashley have never tired putting insulation boards under the carpet before so not really sure if that would work as depending how solid they are would depend on if the gripper could be used on them. My recommendation would be first putting paper felt down taping all the joints this would stop any draft, also seal the skirting board to the edge of the floor with a sealant to all stop any draft there. I would then recommend a underlay with the highest Tog Rating the higher the rating the better the thermal properties, such as Cloud 9 Cirrus, Cumulus, Tredaire Softwalk & Dreamwalk. A good place for underlays is http://www.tradepriced.co.uk/index.html. Also depending on the carpet, how old it is and what it is made of i would maybe recommend a new one, if it just a felt back then something 100% wool would keep the heat in a lot better and feel a lot warmer. With the bathroom you can get a cork underlay which you can stick to the floor and then stick the vinyl to that which would work much the same as for the carpet . if you have any question please get in contact regards jason

Totally agree with above accept you won't get a proper fix for the gripper on insulation boards.

If you can afford it get yourself Underfloor heating and a suitable U H friendly Underlay and Vinyl Flooring. The cheaper option for me would be to use a heavy Wool/Felt or Felt/Rubber Underlay for the Bedroom and a thick Cushion Flooring for the Bathroom. I wouldn’t recommend any installation boards unless they are the type that you have to install plywood on top.

Underfloor heating would work ! Or typically the thicker the underlay the better!