Slab-On-Grade Sinks 2.5 Inches Due to Poor Compaction Under the Slab Synopsis A large section of the floor slab in this two-story house sinks. There are large cracks in the walls, interior door frames are severely out-of-square, and the kitchen cabinets are askew. Main Report General Information Background Description Observations Findings and Conclusions Recommendations Appendixes Appendix B: Floor Level Survey | Structural Inspections | Residential & Commercial Services |