Farmer's Porch Built on House Foundation?

[Josh_V]

This is more of a general building question: I'm playing around at designing a home using HD Pro. I am looking to put parking for up to six cars UNDER the house. Obviously, this is going to require a large foundation. However, I also want to limit the finished living space square footage. I was wondering what problems it might cause if I put a covered farmer's porch, built on top of the house foundation, to take up part of the footprint of the foundation, and thereby "limit" the finished interior space square footage.