Hello!
I took down the ceiling in my renovation project because of some suspected irregularities in the ceiling. Sure enough, the joists also showed signs of having been wet but were now dried. I removed the joists and then encountered sawdust insulation and called in a vacuum truck. Now that everything is exposed, you can see all the way up to the outer roof's sheathing. It looks like water has been leaking over time at one of the rafters and running along it down to the outer wall.
I know too little about the wall's construction. What do you think, is there insulation inside that might have been damaged by the water? And should I tear open the wall or can I just leave it as is? It's a brick house from 1957.