Unquestionably Confused on Wed, 1 Jul 2020
23:54:37 -0500 typed in rec.woodworking the following:

I don't know that I've ever seen a 4"x8" board, let alone one used as a
header. Two 2x8's nailed together should do the trick. I used 2 2x6's
as headers in my garage shop without any problem.

I assume that the 8" is called for in the case of your span.

When I built the garage, I used a pair of 2x10's (IIRC) bolted together
with a "flitch plate" sandwiched between them. Plate was a 2x10 piece
of 3/8" steel. 34+ years later, with midwest snow loads there has been
ZERO deflection on that 16' garage door header.

As for the rest of the "problem", I'm not sure I understand what you're
asking so I won't volunteer anything other than to suggest what you're
already considering: Right sized windows to begin with.

Have you thought of hitting a "Habitat for Humanity" resale shop?
Amazing what you can find there.

I hadn't. But with the shutdown in Washington, I'd forgotten
about that.
--
pyotr filipivich
Next month's Panel: Graft - Boon or blessing?