Solid Floor Construction

For solid floors the underfloor heating system is laid onto an insulation layer before the screed is poured, neatly containing all of the pipe work within the floor structure.

This system has the added advantage of maintaining the floor structure depth exactly the same as it would be without the heating system.

Solid floors offer the best performance for underfloor heating. Screed is made up from a sand-cement mixture at different ratios depending on your requirements. Because the screed conducts heat effectively, it’s the ideal companion to an underfloor heating system.

The conductivity means you will have an even spread of heat throughout the whole floor area. During installation, Underfloor Heating pipes are laid on top of a layer of insulation.


With a concrete solid, screeded floor, the screed acts to diffuse the heat across the surface ensuring the temperature at a constant even temperature.

There are few methods for installing wet underfloor heating pipes in concrete floor structures, depending on the type of building or type of construction.

The most popular method is as follows:

A concrete slab is laid over a wet-proof membrane. A 20mm thick piece of insulation is attached to the external walls, to a height that includes the depth of floor insulation and screed.

Do not worry if you can see the edge insulation – it will be covered by the eventual plastering or skirting boards.

The insulation is laid out over the whole area and the joints are taped to prevent the ingress of screed between the insulation boards. Now you are ready to install the wet underfloor heating pipes.

It is recommended that you use a minimum layer of 50mm Polyurethane insulation. Please remember that all insulation requirements need to comply with the current building regulations.

A 65 – 75 mm screed is laid on top of the insulation and piping.

When using polystyrene insulation (50mm) wire mesh is recommended on top of the insulation and then tie the pipe to the mesh.

50 mm liquid screed can also be used for screeded floors. With liquid screed it is important to install a plastic membrane on top of the insulation and to use the edging strip around the perimeter of the walls.