How much thermal insulation do rubber granulate floor coverings provide?
Floor coverings made from PU-bound rubber granulate add a thermally insulating layer, but they are not thermal insulation in construction terms. The effect comes from the combination of rubber granules, polyurethane binder and air-filled pores. The key factors are the thickness of the covering and its thermal conductivity.
Thermal conductivity, represented by λ, describes how readily heat passes through a substance. The lower the value, the lower the heat flow for the same thickness and temperature difference. Depending on the product range, rubber granulate floor coverings have a thermal conductivity of about 0.07 to 0.16 W/(m·K). Expanded polystyrene (EPS) insulation is significantly lower at about 0.035 W/(m·K). The covering has an insulating effect, but it does not replace a separate insulation layer.
Where an element of the building fabric requires thermal insulation, for example a flat roof over a heated space or a floor above an unheated space, the covering cannot take its place. In open-pored, water-permeable ranges intended for external use, the insulating effect is also lower when the covering is wet than when it is dry.
The practical effect becomes apparent over a cold substrate. In unheated cellars, workshops and on terraces, a dry covering initially draws less heat away from the feet, so the surface feels less cold. On roof terraces, the covering shades the roof membrane and slows its daily temperature cycle. When laid over underfloor heating, the same property acts in the opposite direction. As the covering becomes thicker, the surface responds more slowly to changes in the heating controls.