A PolyVoid designed suspended slab must be 'fully piered'. This means that the entire slab is supported by piers spaced at intervals set by the engineer.
Whilst we openly promote that any pier type can be applied such as a steel screw-in, concrete, timber etc., there is no question that a screw pier system is more efficient, and easier for slab construction.
Given that the slab needs to be fully supported by the piers, there must be contact between the two. This in turn means that the piers need to protrude up from the ground to the height of the voids being used for that system in order to meet up with the underside of the slab.
Any form of 'driven' pile can achieve this with ease as they can simply be driven to the required height or cut-off post installation whereas a concrete pier would need to be 'brought up' to meet the slab and therefore some additional form of form-working would be required in order to do so.
A PolyVoid slab is only as good as the piles of which it is founded. Any form of piling must be installed by a highly reputable contractor, and in accordance with all of the relevant governances.
The beauty of a PolyVoid slab is that the piling method used is entirely your choice.