Concrete ground slab design
Raft slabs, waffle pods and infill slabs designed to AS2870 — for the ground you are actually building on, not a generic detail.
Services / Concrete ground slabs
Choosing the right slab
Concrete slabs are a common footing solution for residential, commercial and industrial buildings. For housing, the slab is generally designed as a stiffened raft, a waffle pod, or an infill slab within a perimeter footing.
Which type is right depends on the ground, the building above it, and how the site is expected to move over time.
Hunter Valley ground moves
Foundation conditions change sharply across this region. Sandy profiles near the coast behave nothing like the reactive clays through Maitland and the valley floor, and two sites a few streets apart can classify differently. Reactive clay swells when it takes up moisture and shrinks when it dries, and that movement is one of the things that leads to cracking and other slab problems.
AS2870 handles this through site classification — A, S, M, H1, H2, E or P — which sets how much ground movement the slab must tolerate. The classification drives the beam depths, the reinforcement and the articulation, so getting it right early is what keeps the job economical.
Start with the ground, not the drawing
We recommend engaging a qualified geotechnical engineer before design begins. Their report establishes the soil profile and the site classification, and the slab is then designed to suit — substantially reducing the probability of damage to the structure over its life.
It is a modest cost at the front of a job. Many of the slab problems we are asked to look at later can be traced back to ground conditions that were not properly understood at the start.
What you get
- Slab and footing design to AS2870, suited to your site classification
- Drafted drawings the slab crew can build from
- Reinforcement layout and specification
- Drawings and documentation for your DA or certifier