What The Texas Board of Professional Engineers Says About Elevation Measurements
The Texas Board of Professional Engineers recognizes three levels of foundation performance evaluation: Level One, Level Two, & Level Three. Here is a brief explanation of each level.
Level 1: This is a visual inspection. There are no elevation measurements of any kind.
Level 2: This is a Level One evaluation that includes elevation measurements. The elevation measurements should be sufficient to identify the dominant distortion mode. Generally speaking, the purpose of making elevation measurements is to understand the overall shape of the slab surface. The shape of the slab surfaced allows the engineer to judge the distortion mode of the slab: center-lift or edge-lift.
Level 3: This is a Level 2 investigation that includes materials testing. I have never heard of a Level 3 investigation being used in a real estate transaction.
Regardless of the purpose of the elevation measurements, they should never be the sole basis of a recommendation to repair or not to repair the foundation.