And that's probably a good thing.
We are in design on this modern hillside home built in 1960. While the views are amazing, the owner has admitted that he sometimes wakes up at night a little unsettled. We can't disagree. This house has only one wall resting on the ground. The remaining structure, in its entirety, is floating in the air, supported only by the steel columns.
The new design will have a lower level built below the main existing level. This new level will act as a new foundation for the older existing structure. There will also be a deck and pool level below the new lower level. This will give the owner much more needed space, as well as help him sleep peacefully at night.
For a brief summary of the changes to structural building codes: see Evolution of Codes
For a more in depth look at how codes have evolved: see Evolution of Codes in the USA