Raft Slabs vs Waffle Pods: What’s the Difference?

Transcript

Charles Christodoulou: “Now in Adelaide and then they invented what we call a waffle pod. So there’s two, you can write this one down, Joe. There’s two types of concrete slabs. One is a raft raft slab R A F T and the other one is a waffle pod.“

Charles Christodoulou: “A waffle pod sits on top of the ground. the raft slab you they dig trenches in the ground and fill them up with they call them they call them the concrete beams and there’s internal and external beams uh and then so they invented the waffle pod in to be used in Adelaide parts of Adelaide because of the extreme uh soil conditions they didn’t want the saw cracking a concrete slab. So they thought, “Okay, well, we won’t dig into the ground. We’ll sit it on top of the ground.” I said, “My house is built on a waffle pod.”

Charles Christodoulou: “The waffle pod. They’ve got the foam pot, foam squares. So they’re about a meter by meter and they sit them on top of the ground and they leave gaps between each pod of about I think maybe 150 mil or 100 and then they pour the concrete on top of these polystyrene boxes and that’s what we call and that forms the beams in between. And then they pour 100 mil of concrete on top of the polystyrene boxes. And then you’ve got your waffle pod.“

Charles Christodoulou: “The raft slab they pour the they pour the concrete on top of pack sand. They have each pad is about – probably 1,800 by 1800 there. If you can imagine sand packed up at about 300 high then they pour the concrete on top of that.”

Two types of concrete slab foundations with different construction methods and soil suitability.

Raft Slab

Dig trenches in the ground
Fill trenches with concrete beams (internal and external)
Pour concrete on top of compacted sand
Each sand pad is approximately 1,800mm x 1,800mm
Sand is packed to about 300mm high before concrete is poured

Waffle Pod Slab

Polystyrene foam squares (about 1 metre x 1 metre) sit on top of the ground
Gaps of approximately 100-150mm left between each pod
Concrete is poured over the polystyrene boxes
Forms beams in the gaps between pods
100mm of concrete poured on top of the polystyrene boxes

Key feature Sits on top of the ground rather than being dug into it.

When to Use Waffle Pod Waffle pods were invented for use in areas with extremely reactive soil conditions (like parts of Adelaide).

Why it works Because it sits on top of the ground rather than being dug into it, the waffle pod "floats" and prevents soil movement from cracking the concrete slab.