Chapter 6 case study: Ground floors and the formation of ground supported floors
It is essential that the ground supported floor is formed on a firm base. In order to achieve this a bed of hardcore is provide which is well compacted so that settlement following construction is avoided. Here we see hardcore being compacted beneath the floor section of a raft foundation. In other forms of construction the hardcore is placed within the enclosure formed by the walls up to ground level.
Excluding ground water
One of the most common forms of ground floor construction is the concrete slab. The slab is laid onto a bed of blinded hardcore with an impervious membrane sandwiched between. Here we see the completed slab with the membrane dressed up at the edges. It is essential that this membrane is overlapped with the damp-proof course in the walls in order to effectively exclude ground water.
Formation of suspended concrete ground floors
The use of beam and block floors is now very common in the construction of dwellings. Although timber floors are still used in some cases, they are now rare. In the illustrations we can clearly see the regular layout of reinforced concrete beams with lightweight concrete blocks set between. The size of units is such that they can be easily manhandled. The assembled floor is now ready to receive a sand and cement slurry to give a smooth finish.
Where internal walls and partitions are to be provided the floor must provide adequate support. Here we see two reinforced concrete joists set side by side to support a wall above. Where the wall runs at right angles to the joists there is no need to provide additional support, since the weight of the wall is distributed across several joists.
The floor joists are supported by the external and internal walls of the building. Due to the considerable mass of the floor structure there is no need to provide fixings at the connection between wall and floor. The mass of the floor ensures that it remains in place.