Unifloor, subfloor preparation systems

Underfloor heating - Proper insulation in underfloor heating is of crucial importance

In recent years, underfloor heating has become increasingly popular and traditional radiators are slowly disappearing from (new) homes. Smarter and more efficient heating uses less gas and therefore emits less CO2 during the production and transport of the gas. Roughly 2 kilograms of CO2 is emitted per cubic metre of gas produced and distributed! Therefore, electric underfloor heating supports the goal of reducing gas use and responds to consumers' growing awareness of the impact that burning fossil fuels have on the climate. How can the optimal efficiency of underfloor heating be ensured?

Proper insulation is critical for optimum efficiency of underfloor heating. The insulation layer beneath the underfloor heating source is essential for a well-functioning system.

We have several electric underfloor heating systems and editions but the principle structure is the same for all systems. You start with an insulating subfloor on the existing flooring/subsoil, where the underfloor heating mat is placed. Then the final flooring finish is placed on top. Both the insulating subfloor and the chosen floor finish have an insulating effect, whether the heat passes through the material or not. This is indicated in an R-value (heat resistance). The R-value, therefore, indicates how well a material of a certain thickness thermally insulates or it is an indication of the extent a material allows heat to pass through.

The R-value of the insulating substrate must be high, so that heat cannot escape through the floor. The layer above the electric underfloor heating system, on the other hand, needs to let heat through for the floor to heat up quickly with little energy consumption. The heat always chooses the path with the least resistance. A maximum R-value for the floor finish of 0.15 m2.K/W is specified by the underfloor heating industry, which determines the permeability by the top floor. Please find an example here to clarify the above explanation.


Insulating substrate
R-value 0.17 m2.K/W
Floor finish
Heat-Pak + LVT
R-value (0.072 + 0.03) = 0.102 m2.K/W


Therefore, Heat-Blok® has excellent thermal insulation value and prevents heat from escaping downwards.Heat-Pak® has a low thermal insulation value and therefore easily radiates heat to the top floor. This is the ideal combination, where the effect of the electric underfloor heating is optimal with the lowest possible energy consumption.

Heat-Blok® is made of a high-quality EPS and has an aluminium moisture barrier foil, with overlap and adhesive strip, so that the strips can easily be connected. Heat-Blok® is the perfect insulator underneath the electric underfloor heating, due to its limited thickness of 6 mm and the relatively high R-value. Heat-Blok® is supplied in rolls of 25 m2, which makes the subfloor easy to apply on a flat surface. Cables and connectors can easily be concealed in the subfloor due to the 6 mm thickness. 

Many combinations are possible with Heat-Blok® and Heat-Pak®. Unifloor has listed all possible combinations here for you: