The PolyVoid compressible void former should be used in conjunction with a suspended concrete slab design. That said, given that it is the same dimensions as that of a waffle pod, it can certainly be used in lieu on a conventional waffle design.
It is important to note that whilst the dimensions and material used to make a PolyVoid are more or less the same, it is not a waffle pod. Many alternatives have been tried in the past such as old car tyres and saw dust, however the decision to use polystyrene was a combination of using a material currently used in the building process, and something that represented very little change to a builder and concretor in terms of handling and installation.
The PolyVoid has been specifically engineered to compress under soil heave forces, and polystyrene has made the process of taking an engineered concept to reality, much simpler.
A PolyVoid can be used in lieu of a waffle pod, however a waffle pod cannot be used in lieu of a PolyVoid. A conventional waffle pod does not have the required compressive features of that of a PolyVoid, and therefore, they are very different.
PolyVoid designed suspended slabs may vary in design from one Engineer to another. There are some fundamentals that need to be understood, however there can be variation in design provided the slab is designed in accordance with AS 3600 (Code for Suspended Concrete Slabs).
Providing the right void height is chosen based on the site's heave value, a PolyVoid slab can be designed either using a flat benched site (for quicker installation) or a slightly excavated site (e.g. edge beams). Typically, forming a PolyVoid slab without excavation is the simplest method using two void heights to create the brick rebate, however in some instances, the same void height may be needed across the whole slab and therefore edge beams, patios and garage sections may need to be excavated.
To see some design examples, please click here: PolyVoid Printouts