The reason for this style of foundation is due to the amount of dropoff from the NW corner to the SE corner. I didn't realize the ground dropped as much as it does, but there is almost 6.5' drop. They brought in over 300 yards of dirt to level the pad, so to keep the foundation from settling and breaking, we put in 30 piers and the beams you see in the pictures. The dirt we have in this area has a very high clay content. When it is wet, it swells and supports your foundation well. But as it dries out it pulls away from the foundation, sometimes by as much as 2-3". This much soil movement plays heck with the foundation. I have had several friends not only have foundation repairs, but also plumbing issues because of the soil movement. I'm not anticipating any issue with this slab in the future.