Codes require numerous things, but one important obligation is to sink footings to at least 36 inches below the ground level. We had to dig some special holes and fill them with concrete to do it right.
Footings are what everything else is built on top of.
If the footings are not deep enough, freezing ground can move the structure around. In a sense, you are creating your own rock to build on when you craft footings. Foundation footings are important in spiritual matters as well. Verse 1 tells us we were spiritually dead. Verses 8 and 9 tell of the grace that makes salvation possible.