Well, as an Engineer I would say that if the report makes reference to a "sub-floor" in its wording then it is factually wrong.

 

If its a reinforced concrete slab sitting directly on the ground then it's a slab-on-grade.

 

You can only have a sub-floor if the ground floor is suspended above the actual dirt.

 

Sounds to me like they should be reporting "slab-on-grade ground floor. No defects noticed".

 

Fair enough, there could be a enormous 20mm crack hidden beneath a carpet. But any report is going to contain wording about visual inspection only, no finishes disturbed or removed during inspection, no comment made on condition of any element(s) hidden or otherwise unaccessible etc. to cover their arses.

 

Otherwise, why aren't they marking down the walls for unknown condition of the framing, insulation and wrap because they didn't rip off all the GIB to check?

 

If anything is obviously wrong (unlevel floor, rucked carpets etc.) then it should be in there and flagged.

 

They can also walk the building perimeter and look at the slab edges, where visible, for signs of cracks or movement.