Originally Posted by
rpenmanparker
Near as I can tell, our frost line is at about -5".
That sounds like pier and beam. The short wall is built up from the ground to the joist height for the ground floor. There is no hole in the ground.
Lots of concrete piers aren't visible. The slab just caps them at ground level.
The book I have from college says in mild climates footings are often only a few inches below finish grade.
However in northern states where the frost penetrates deeply the footing is 4 or more feet below finish grade.
Local codes usually set the depth. The footings have to be deep enough to be protected from frost.
You probably don't have a four foot frost line where you live, the building codes from your town would tell you
The book is from 1973. I don't remember too much about 1973. You can probably guess why.