The rotten wood between the upper and lower window is an integral part of the window. You need new windows.

New windows. And proper flashing on all of your windows. Or all will continue to rot.

Unfortunately by the time you source out just about every part for the window and replaced it you could have bought a new window several times over. That window is toast.

OK, thanks for the advice!

+1 to Millworkman's feedback. There isn't much worth saving there, sadly.

Are you sure its all rot and not termites?? I dont think I have ever seen a window look like that.

I finally dug into this project.

As a primer, these windows (as well as the siding in this part of the house) were not properly flashed, which also resulted in rotting portions of the osb next to/underneath the windows. so what was a ”I’ll fabricate new frame portions and replace those” became ”I have to pull of a lot of the siding off around the windows as well, replace/repair the osb (I used plywood), and put on proper housewrap and gap between the siding wood and the wrap”

This house was constructed right before the mass availability of superior housewrap, and the siding ”logs” were nailed directly to the tar paper wrap with no gap . Definately a learning process for me about proper construction.

So to summarize, there were several sins of construction done on the walls and windows, which resulted in this problem and increased the time of this project,

After addressing and repairing the rotted area of the walls and putting on housewrap and vertical furring strips to allow drainage/ breathing betweeen the siding and the wrapped wall, I removed the rotted fronts of the frames (the middle sections), stabilised the remaining good wood, constructed new frame peices, used flashing tape to seal the stabilized remaining wood, and added the frame sections in. On the worse side that i repared sections of the wall, i also added flashing to the top and bottom of the window, and made sure to have weep holes and paths for water to run outside.

The side of the house that wasnt as bad (pictured above) I will address the wall/siding next year. the Frame area was the most critical, so at least i got that done before the weather gets bad here.

I do plan on redoing this whole side sometime in the future, but this should give me a few years to plan that out (and save up) .

I’ll add an after pic, later today if i can get home before it’s dark .

You can also see the leaky pane on the upper right window too. It was since i bought the place in 2020, but has gotten worse over time .

The plan is to eventeventually redo the whole side and put in a single big window here (instead of the 4 panes), a sliding glass door replacing the mirror image of this on the other side, and a covered porch on the whole side here. This repair will get me by a few years until i decide to do that . The rot on that middle section was pretty bad and i didnt want the window to collapse.

Fantastic job! Thank you for coming back with an update.