While the perimeter footings were sound, demolition revealed that a slab poured on uncompacted fill was suspended like a trampoline from the footing edges. Note the bow toward the center of the slab remnant.
Careless site preparation at the time of construction left this 30-year-old home with a sinking driveway, a cracked and leaking sewer line, and failed slabs in the garage and the family room behind it.
With the drywall stripped from the laundry-room and family-room walls, the sag in both slabs is evident. Note the inspection hole in the concrete.