More about stiffened raft slabs
AS 2870 provides the required minimum dimensions and specifications for the depth, width and spacing of beams in a stiffened raft slab footing.
The excavation depth depends on:
- depth of adequate bearing soil below the surface
- depth of vegetation
- slab height.
The height of the finished concrete slab floor level must be specified or calculated before construction. This ensures that the completed floor level finishes above the surrounding ground level. Raising the slab level above the ground level makes sure that floodwater or stormwater cannot readily flow into the house and cause water damage.
The minimum recommended distance from the top of the slab to the finished ground level (FGL) is 150 mm. Note NGL on the diagram which refers to natural ground level.
Turn to your copy of the BCA and refer to the following:
- Figure 3.2.5.3 (a)
- Figure 3.2.5.3 (b).