I'm currently welding up a metal building and will be framing out my window openings with 8" cee purlins.

What are the advantages and disadvantages of attaching my new construction vinyl windows directly to the purlins versus framing out with wood inside my purlin window frame?

I've seen both done on YouTube, but would like to hear from you.
Thank you

My first thought is that you'll have different heat transfer with the wood and metal since heat goes through metal a lot easier than wood. You also have different expansion and contraction between the two.

I didn't know about the advantages and disadvantages of either, but that's where I'd start. Also, how do you plan to finish the inside of the window? That may be another factor.

Thank you ABATTBQ11. I went ahead and secured the windows directly to the purlins. I've moved on to the wood framing portion of my build now. I'm going to have about a 12" window sill on all windows with the 2x4" interior wall plus the 8" purlin exterior wall, but I'm okay with it. I am concerned about sheetrock around windows cracking if the metal barn expands or contracts too much, so I might opt for plywood instead of sheetrock on my window openings. I'm sort of figuring this out as I go, so we'll see...

I would definitely use wood around the windows. Not just a problem with expansion, but moisture, weight capacity, etc.

I'm currently building a barndo in Fayette County with my family as my crew. We opted to do 2x6 exterior framing of the home portion between the beams instead of purlins.