dude... steel comes with 8" exterior load-bearing walls. My company
fabs snow and wind loads into the steel itself and then sends it to you
without any cutting or welding on-site. Just bolts together. You can
finishi out the home any way you want, but keep in mind, since none of
the internal walls are load-bearing, one can move around internal
partitions easy-as-pie. If you are looking for better insulation,
wouldn't it make sense to build out of a non-purous material?

JG