Tim Wescott wrote:

"Chuck" wrote in message
I'll be building a carport in the near future. I would like to make my own

I-beam would be better, it would put the most metal where it's stressed the
most.

I-beams are quite unstable side to side and in torsion. They only work
well if there is some form of diaphram or or other additional support to
prevent twisting and/or sideways motion. That's why I usually prefer to
use rectangular tubing.

Ted