1. Ensure the concrete slab is fully dried out, level and free from projections. The floor should have no more than a 5mm deflection over 2m if using Mannok’s PIR insulation boards and no more than 35mm deflection over 3m if using Mannok’s EPS insulation.

2. Lay the appropriate damp proof membrane (DPM) over the concrete slab, ensuring it is well lapped and folded and is sealed to the wall’s damp proof course (DPC). Where radon control measures are required, the specified DPM should be gas resistant.

3. Lay insulation boards in a continuous layer across the whole floor. The boards should be butted tightly together and laid with joints staggered between rows. Boards should be cut neatly around service penetrations to minimise heat loss through thermal bridging.

4. Install preservative treated timber battens where high point loads are expected, for example at thresholds. The top of the battens should be at the same level as the top of the insulation boards.

5. Overlay the insulation boards with a polyethene slip sheet taped at the joints. The sheet should have 150mm overlaps and should be turned up 100mm at the walls.

6. The timber floor can now be laid over the polyethylene sheet.