OSB dintegrates once wetted -- the swelling wood fractures the glue and
it falls apart. The structural strength is questionable new -- as my
brother demostrated, a healthy guy can easily drive a 16 oz hammer
through a 3/4" sheet of OSB. I dont' know of anyone who can pull that
trick with Douglas Fir plywood.
TGI trusses are horrible, they are both weaker (lower fracture
strength) and much more flexible if not installed exactly vertical than
2x12s. Water again, any water at all, even high humidty for more than
a few hours, and the material disintergrates.
Use steel -- if protected from severe water incursion, it will last
hundreds of years, and doesn't warp. With the ease of construction, is
should be cheaper than wood by now, and it can ONLY be installed
square.
Peter
