The purpose of the substructure of a building is to transfer the loads of the superstructure to the soil that is underneath. This is why the substructure is right against the soil that supports it.

What is the purpose of a substructure?

It suggests that the function of the substructure is to, '… transfer the load of the building to the ground and to isolate it horizontally from the ground.

What is substructure in construction?

The substructure is that part of a building or other structure which is below the ground, unlike the superstructure which is above the ground. Typical stages or elements of the substructure, such as foundations, are listed in the margin.