mathew figured out the leak: an incorrect installation of exterior siding. on sunday we covered the wall openings with gypboard.
(left) the original plaster wall! (right) installing gypboard.
mathew drilling holes in the 2nd hallway for blow-in cellulose insulation. the holes go between each stud. once those top holes are drilled he drops a string and plumb inside to find where horizontal pieces might block the insulation, then he drills more holes below that.
we decided to strip the old paint and plaster skim coat off this third wall. pounds/gallons and years of paint were removed. then we stripped the 2 layers of wallpaper. the exposed plaster walls are quite beautiful in a rustic way, they look like walls in old buildings in europe.