Ground bearing floors can include insulation either below or above the concrete slab, depending on the choice of the designer. If the insulation is installed below the slab, this increases the thermal capacity of the building, helping to maintain steady internal temperatures.
If insulation is installed above the slab, the building will respond much more quickly to the heating system. Suspended floors are usually insulated in such a way that they offer reduced thermal mass and respond quickly to the heating system.
Insulation is placed between the joists and supported on netting (e.g. polypropylene) or timber battens.
An important consideration is to ensure that the insulation product used fills all gaps between joists to prevent air movement which can lead to unwanted heat loss.