The middle rail (why does this thing even exist??) needed to be cut to allow the insertion of our new window framing.
Hans wrote:. To nail the middle of the vertical shiplap siding. In my fathers day they avoided it by putting the shiplap on at a 45 degree angle which braced the structure at the same time. He did that building concrete forms for our infamous Purdy bridge.
Just a tip for anyone looking at copying this style or learning from it- This would
not be typical, as it’s a weak form of framing. Normally studs are run full length (base to top of wall) then put the horizontal pieces in between. Years ago they were called ‘cats’, not sure why. It’s done as fire blocking on runs taller than 8’, but can also be done for the reason of vertical siding like board and batten or board and gap. BUT- also typically, if you are running vertical siding you would install horizontal purlins first. All the little 45 angle braces were needed here because there is no diagonal support as would be typical with sheathing, or, as Hans mentioned, running the siding boards at a 45 degree angle. But if you install purlins 16” on center, that will strengthen the wall adequately on a cabin or shed this small.