On Thursday, July 2, 2020 at 12:11:00 AM UTC-5, DerbyDad03 wrote:

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.

+1. Do you understand what Derby is saying, here?


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.

Compare the price of 2X8s and 2X10s.... not really much difference. Use 2X10s, at the least.

Probably doesn't matter how low your window is. Just don't have your sill, if any, poking out to interfere with your bench. No telling, you may move the bench to another location, later.

Sonny