Hi all, been here many times and found good advice, just never had the need to ask a question myself until now.
After several attempts with words, I decided pictures are the only way I could ever get this described. This house was moved many years before I was born and set on this foundation. On the outside of this exterior wall, they laid brick alongside the foundation and existing lap siding, right up to the windowsill. It appears the windowsill split (wall settled?) leaving a space behind the brick for water and bugs to get in and wreak havoc on the lap siding, and after that, the interior wall boards and studs of window frame. As you can tell from pics, the interior oak(so I was told) wall boards are rotted and some lightly eaten(termites), so first question is how should I replace these interior boards? I've read advice from others mentioning them being structural. Second question is what should I do about the area under the window? The lap siding that once existed is now completely gone, so my only barrier is this brick. Should I try to attach some sheathing between the wall and brick? What's the best way to accomplish that if so? (only about 1-2" working gap there)
First pic shows looking down at sill (brick outside, sill split)
Second pic shows wall under window (I replaced framing already)
Third pic shows wall (one drywall sheet removed, some vapor barrier, wood plank wall behind barrier, insulation, lap siding on outside - mostly gone or falling)