Quality of Slab Foundation

Hello:
Trying to understand the different aspects of a slab foundation. What's really started my curiosity, is I've noticed several production homes seem to be built only a couple inches above the ground. Meaning, the concrete from the slab only seems to be a few inches above the grass line then the exterior (stone, stucco, etc) starts.
My first reaction was to think this is the sign of a cheap foundation. Guessing there was not as much concrete used would imply (guessing) that the foundation is not as sturdy as a foundation you could see a foot or so of concrete at the base of the house.
However, could this also be the area for the concrete to be poured was simply dug down and could have the same amount of concrete, but it is sitting deeper that one you see a foot or two?
Also, can various amounts of steel, iron/rebar be put into the mold of a foundation to make it stronger? Is this essential? And why do some pre-pour sites seem to have groves dug out before concrete is poured?
Thanks!
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It depends upon what the architect/builder has decided the 'FFE' ('Finished Floor Elevation' will be. A typical FFE is 8 inches above the final graded elevation for the house.
Dave

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said...

Wouldn't that be a minimum?
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