Floor Insulation

Heat is lost through the floor, particularly if it is solid (e.g. stone or concrete with tiles over), or as a result of draughts (e.g. gaps in a suspended wooden floor). Both are worth thinking about, especially if you are planning other work (plumbing, electrics etc) which might involve taking up the floors.


The flow of cold air that you can feel through the floor is the direct response of a gap somewhere letting the warm air out.

Solid floors

Normally the only opportunity to insulate concrete or solid floors is when they are being laid in the first place. When you have an existing floor, you can insulate (your feet) by putting a layer on top of the stone or tiles. For instance, coir matting or cork tiling will prevent it feeling so cold and limit the rate of heat loss.

In older properties, breathability must be considered when doing work on solid floors (as with walls). Concrete flooring can lead to damp problems so care must be taken to allow moisture to escape rather than being forced up the walls. Limecrete flooring is generally more sympathetic, and can be laid with a layer of insulating aggregate- this is a specialist job, but there are a number of local builders with experience in this area.

Suspended floors

The gaps found in wooden floors can be filled with an appropriate-coloured caulking if you have bare floor boards. When sanded and varnished these are hardly noticeable and are long-lasting. If you intend to put a carpet down, a good underlay or even newspapers can help to limit the air flow. A thorough job involves putting a strong membrane down, over the floorboards and, ideally, taking this up the walls under the skirting boards. This will, of course, require temporarily removing the skirting boards, but the quality of the seal is much better. Then the underlay and carpet can go down as normal.

Geek says

  • If you are putting in underfloor heating, it is essential to make sure that the underside is properly insulated, otherwise you will be heating the earth, not your room!

Local experiences

The Boardman’s used ACH Oxford to have our wooden hall floor sanded, and the gaps filled, several years ago and are still happy with the result.


Tina Leonard has been looking into replacing her carpets with something beautiful and ‘green’ and has decided to go for strand woven bamboo from ‘Simply Bamboo’. She is very happy with the result: ‘It looks good and feels lovely. So much nicer than carpet!’


Caroline (OX2): we had terrible draughts in front room/hallway from ill fitting skirting boards and air coming in through an external air vent into the space between the ill fitting original bare floor boards and the space between them and the earth 2-3 feet below. We decided to have some underfloor insulation installed and we used Kingspan, but with hindsight we probably should have researched the type of insulation that could be used more thoroughly. A builder we have known for a long time – works on his own – installed the insulation for us at a cost of £1200, which took a week with minimum disruption to us.

The resulting benefits have been an amazing increase in thermal comfort – no draughts, with air still circulating beneath the insulation. We can now sit with our feet on the floor not on the sofa! We can lie on the floor and feel warm and the room warms up more quickly. As part of the insulation was under the passage between the front door and the stairs that also makes a difference to the temperature in the rest of the house.

Useful links

Thermal imaging of floors



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