We worked on a six-storey apartment block in Brunswick where the structural engineer specified a raft foundation to spread the load over variable clay layers. Before pouring the mat slab, we ran a series of boreholes and a plate load test to confirm the modulus of subgrade reaction. That data directly shaped the slab thickness and reinforcement layout. For Melbourne sites where you have stiff clay near the surface but softer material deeper down, the raft becomes the logical choice because it bridges those weak spots. Our job is to give the design team the numbers they need for settlement and bearing capacity.
A raft foundation in Melbourne typically requires a minimum of three boreholes per footprint to capture lateral variability in clay stiffness.