The raft foundation slab

Ground-floor slabs that are also raft foundation may have steel mesh reinforcement in the slab and the edge beams. The following steps show how to make a simple raft foundation slab.

1. Support the reinforcement 25 mm above the dpm by fixing cement spacers underneath the bars so that the concrete can flow all around them.

2. Build vertical formwork on struts along the outside position of the edge beams to contain the concrete.

3. Pour the concrete so that it fills all the spaces on the slab.

4. Spread hardcore and blinding in the measured area.

5. Divide the area into 3 metre by 3 metre bays (Figure 11.4)

6. Lay the reinforcement, the mesh for the slab and the bars in the edge beams in position.

7. Lay the dpm over the blinding.

8. Fix boards over the reinforcement to prevent the concrete leaking out.

Figure 11.4 Laying the Oversite Concrete into Bays

11 Fill in the gaps in the following passage with a suitable preposition given below: