Maybe this should have been lesson #1 - it’s such a common mistake. The oft-neglected rule is this: not every house plans fits - or can easily be made to fit - on every site.
Potential Disaster
You’ve seen the sad, odd result of this mistake before - the one-level house precariously perched on a steeply sloping site. In the Midwestern and Southern United States it’ll be supported on stacks and stacks of concrete block; in the California hills it’s even worse - houses on stilts! But it does make for great video when a mudslide or earthquake takes one into the ravine below.
