Slab foundations are a different situation. Some buildings don’t have a crawl space but are built on a slab of concrete. This type of construction can be undermined from erosion, poor soil compaction or water table and soil shifting. These slab foundations can sink and crack and are repairable by excavating the damaged area and lifting the concrete slab to the original and correct elevation. The re-leveled slab is then permanently supported the with steel push piers driven deeply down through the soil into solid and stable strata. The excavation is then refilled with soil or gravel.