DerbyDad03 on Wed, 1 Jul 2020 22:10:57 -0700
(PDT) typed in rec.woodworking the following:

Well, actually, the header doesn't necessarily go at the top of the wall.

"It does if you're trying to fit a tall window" B-)

Technically, it goes above the rough opening. Depending on the height of
the wall and placement of the rough opening, there may be studs between
the header and the top plate of the wall.

See he https://www.shedking.net/images/shed-framing-names.jpg

That said, Yes, building your own header is OK and probably the most common
method of creating a header. For 2 x 4 walls, you should seriously consider
adding a piece of 1/2" ply or OSB between the 2 x X's to build it out to the
full width of the 2 x 4 top plate.

As the header on these walls are 2x4, well, it doesn't matter. The
Window frame is going to be more than 4 inches 'deep'. My current
thinking is to use a 2x6, and remove a "right sized" grove so I can
have the two window panels fit ... and I'll get back to you on that
when I confirm the dimensions.

However, I'm pretty sure that an 8' rough opening in a single story, load
bearing wall requires a minimum of a double 2 x 10, not 2 x 8. It might
need to be even bigger depending on the snow load.

I should have been clearer. While the original window was 8'
wide, the parts I'm repurposing are 2 feet wide. If I use both of
them, I have a 4 foot 2 inch span.

(Old rule of thumb was width of opening plus 2)

Should we stop right here and not worry about your other question?

Yeah. Priorities have changed for the next five weeks.

--
pyotr filipivich
Next month's Panel: Graft - Boon or blessing?