While that's all good, and I'd love to do that, adding inches to the outside of my house isn't really possible since I only have so much room on either side of my house before it becomes my neighbors yard...and I need to be able to walk around my house. I think there also may be some building restrictions needing a certain amoung of space. Plus, the front of the house would look really weird if I added size to it.
And if I added it inside, I'd lose a lot of living space. My kids rooms are already kind of small...this would make them really small. Not to mention my garage would shrink too since it's attached.
I'm not saying it's not completely possible, but this would cost a lot more money to do then I'd really want. I'd have to do some kind of combination of inside and outside expanding.