SOLID GROUND FLOOR BELOW SLAB
Solid floors can lose heat through the ground under the floor as well as through the floor perimeter. The amount of heat lost depends on the size and shape of the floor area and the temperature difference between the inside and outside of the house.
Solid ground floors can have high density rockwool board insulation fitted above the concrete slab or below the concrete slab. If insulation is installed above the slab, the building will heat up and cool down quickly in response to the heating system. If the insulation is installed below the slab the thermal capacity of the building will be increased and the solid floor structure will absorb heat and release it into the rooms gradually over a period of time.
THERMAL BRIDGING - SOLID GROUND FLOORS
To avoid cold bridging at the wall to floor junctions, it is usual to continue the wall insulation down level with the bottom of the concrete slab or to install 25mm of rigid board insulation vertically between the edge of the slab and the block work inner leaf.
UNDER FLOOR HEATING SYSTEMS
In solid ground floor situations under floor heating pipes or cables can be fitted in the concrete slab or screed. In either case the rigid board insulation must be located below the heating system. In a solid concrete floor the position of the insulation is important in either exposing the thermal mass of the concrete floor to the heat provided by the system or isolating the thermal mass from it.
Where the heating is provided intermittently and a fast response time is required, it is beneficial to have less thermal mass and so locating the insulation below the screed or timber floor and above the concrete slab is the most efficient solution.