When I do a prepour, I use the design drawing and my own laser level. I do the items in Wayne's list plus, as he alluded to:
13. Are the forms level, square and straight?
14. Do the overall form dimensions meet the drawing?
15. Do the floor plan drawing and the foundation design drawing agree? (They are usually done by different companies)
16. Plumbing locations.
17. Are the floats located properly?
18. Average rebar spacing in the mat, and average stirrups spacing.
19. Is the moisture barrier sealed around plumbing?
20. Is the PVC protected with mastic or sleeving?
21. Electrical locations and installation methods.

Interesting findings have included:
1. Almost 4" difference in form elevation from one end to the other on a 1900 sf slab. Contractor's laser level was bad. Contractor thanked me.
2. A toilet that would have been in the family room. The builder could have called it a convenience feature.
3. Fairly frequently, the drain to support the upstairs fixtures is forgotten.
4. Fairly frequently, the forms are not square.
5. Exterior rooms, wings, oversized or undersized. Once I found a room that would have been 3' too long.
6. Missing or extra brick ledges. This one really messes up plumber's locations.
7. Inappropriate use of brick ledges, or not, for the intended siding.
8. Thin slab areas. Sometimes as this as 2".
9. Soft pads.
10. Buncha other stuff.

While I also experience occasional difficulty being there at the right time, I don't think the inspection is usually worth while to the contractors and to the home owner. I agree, all of this should have been found by the builder, but you can say that with any defect found during new construction. Builders are human too. Most of them are supportive of a thorough, unbiased inspection. It saves them time and money in the long run.

Darrel Hood
DILIGENT PROPERTY SERVICES
(936)827-7664