I've read all the replies and it seems everyone is answering in terms
of what they have at hand. But you are talking about building new,
from scratch. That's quite an investment and it pains me to think
about all that new construction for only 9 feet of width. On top of
that you're talking about building it as an addition to your house. It
seems to me you are going to be getting very low bang for the buck,
that is overbuilding. Have you considered selling the house and
finding something with more room?

Bob