I've seen quite a few homes that have metal flue inside with a
decorative masonry "chimney" above the roof line. Don't know
what code requirements are for this, but as long as you're going
to have to look into your local code requirements anyway, it
might be an option to consider.

--
is Joshua Putnam
http://www.phred.org/~josh/
Books for Bicycle Mechanics and Tinkerers:
http://www.phred.org/~josh/bike/bikebooks.html