Adding insulation to an existing solid floor not straightforward, but it will help you make sure your whole house is keeping the heat in.
If your house has a solid concrete floor, then there are two ways it can be insulated.
It may be possible to add a layer of rigid insulation board on top of the existing concrete, with a layer of boarding on top of that to create a new floor level. You will lose some headroom, and you will have to move or adjust skirting boards, doors, any fitted cupboards, and maybe electrical sockets or plumbing.
The alternative is to dig out the existing concrete, dig down further and add a new damp-proof membrane, a layer of rigid insulation and a new concrete screed or other flooring. This is an expensive and disruptive job, and is usually carried out as part of a major refurbishment project, or when there is a problem with the existing floor.
If you have an old solid floor made of stone flags or similar, then the best way to insulate it is to remove the flagstones, dig down and add a membrane, insulation and screed, before re-laying the stones. This is a big task, but it has the advantage of adding a damp-proof layer which probably wasn’t there before.
Is it right for me?
If the ground floor of your house is made of a solid concrete slab, or flagstones or similar, with no air gap underneath, then you may want to consider solid floor insulation.
Some houses have a ground floor that is built of horizontal timber joists, with floorboards or other boarding over the top, and a gap underneath. Other houses have a concrete slab, or flag stones, quarry tiles or similar, sitting directly on the ground with no air gap beneath. If there is no air gap then you have a solid floor.
If the house was built after 1995 then it probably has some insulation already built into it. If not, you may want to consider insulating your solid floors.
Insulating a solid floor requires a lot of work, and can cause significant disruption in the home. You may want to consider insulating a solid floor at a time when you are doing major work in that room anyway.
If your ground floor is a timber floor with an air gap underneath, then this is called a suspended floor, and is much easier to insulate.