Like Tim said, the wood frame barns we have acquired have had to have the posts replaced.  The Butler barn we use for the shop had a fire.  Sons 4whlr caught on fire beside several hundred bags of seed corn.  The plastic gas tank melted and gas went everywhere catching some of the corn on fire.  The barn was tight enough it used up the oxygen and then smoldered all night.  The fire was right beside a wall and would have burned through if it were a wood barn.

The next ones we've put up have been metal.  It is a little harder insulating, running wire etc but if we get a little leak it's no big deal cause I'll be dead and gone before the metal rusts through.

Also, that rolling chain hoist on the ibeam is pretty handy.