MS Channel or Square Pipe ?? Which is better for Structure ???

I sized the wooden posts, beams and purlins of my corrugated-steel-roofed sheds for a snow load of 60 pounds per square foot. They have also held up well to hurricanes and large falling oak trees.

There are many load tables and calculators like this on line.

Pressure-treated wood is often southern yellow pine (SYP).

-jsw

and just as aften it is some kind of spruce or fir, or even tamarak. Anything with needles instead of leaves is fair game - - -

Then it's labelled SPF, spruce/pine/fir.

I buy a little extra and put away the planks that dry straight to make replacement exterior door and window frames.

-jsw

I wasn't aware that SPF came in channel or square pipe[sic], guys. And why aren't you doing this guy's homework for him, anyway? He needs all his time to party on Christmas Break. Oops, sorry. That's Holiday Break. Can't be religious. (unfair to Muslims/atheists) ;)

I'd go with SIPs nowadays. Pre-insulated and you can hang a bit of shelving on the inside without a problem. Rock solid, too.

For a metal framing, I'd likely go square tube. Jus'cuz. What size and wall thickness should I use, scplpurchase3? I won't tell you the use for the building, what size it will be, what weather it's in, or whether it will be insulated, either. Those details might completely change your advice.

"I want you to build a boat for me. How much will it cost?"

Saturnalia, for the crypto-Romans. Toga! Toga! Toga!

Yeah, it was a nice party.