1. Get the walls ready
The foundation walls are built up to the level shown on the layout drawing, with the right void depth below and the ventilation in place. The tops of the bearing walls should be level and clean, with a damp-proof course where specified.
2. Place the beams
Beams are placed on the walls at the positions and spacings shown on the drawing, usually starting from one end. Each beam needs its full bearing on the wall. Doubled beams go under partitions and other heavy loads, exactly as drawn.
3. Lay the infill blocks
Blocks are laid between the beams, sitting on the beam flanges. A row of blocks laid at each end locks the beam spacing. Cut or slip blocks close up the gaps at walls.
4. Grout the joints
A sand and cement grout is brushed into all the joints between beams and blocks. This locks the floor together and spreads loads, so it should not be skipped. Avoid heavy point loads on the deck until the grout has gone off.
5. Insulation and finish
With the deck complete, a membrane where required, rigid insulation and a screed or floating board finish go on top to meet Part L and give the final floor level.
Common mistakes to avoid
- Moving partitions without checking the beam layout
- Cutting beams on site (prestressed beams must not be cut or notched)
- Skipping the grout or leaving joints open
- Blocking the ventilation to the void