Monolithic slabs serve a dual purpose: a foundation for structure and a floor. This type of construction is typically used for small garages and that are detached from the main structure. This type of slab shouldn’t be poured directly on top soil. It must be constructed on stable and compacted fill. The perimeter of the slab is usually 18-24 inches thick and is re-enforced with at least two steel rods all around. The center of the slab is normally between 6-8 inches thick and is re-enforced with heavy gauge mesh trellis beneath the surface. It is also possible to insolate the bottom and the perimeter of the structure with rigid high density insulation.