Traditional ground floor construction involves laying a solid floor using a large mass of concrete which is important as part of the construction process.
Fill floor area with compacted hardcore and sand blinding to correct depths and height. Lay damp proof membrane over sand blinding then pour and level concrete to specified depth including any required steel reinforcement. The level of the floor should be carefully calculated during excavation to ensure the finish is at the correct height below the doorway thresholds to comply with Part M of the Building Regulations.
A 30mm insulation upstand should be installed around the perimeter of the floor and continued up the wall to meet the bottom of the plasterboard. Using this method will reduce the Ψ value achieved at this junction.
Lay 120mm insulation on top of the concrete slab with all joints taped and sealed, finished with a layer of screed on a vapour control layer. This method will reduce compression of the insulation which can occur when the insulation is placed under the concrete slab and allows for easy installation of underfloor heating by using pipes laid on the insulation secured with proprietory retention clips.
- Once walls are up to damp proof course level the damp proof membrane should be installed and the concrete poured so that the damp proof membrane can continue up and across the wall to be continous with the damp proof course to form a complete damp barrier.
Hardcore should be compacted in stages no more than 75mm deep.
100mm insulation laid in the wall cavity below damp proof course will further decrease the Ψ value achieved at the junction between the floor perimeter and external wall.