Hi, I'm working on a brick two-story flat attached and it has this ugly sag where the bathroom is on second floor.It was definitely water damaged that caused this disaster.I have sistered 4of 5 joists the last is in such bad condition .On top there are four roof joists supported by window wall and some sought of mini roof.Can i eliminate that section of wall and extend all the way back to exterior wall which is part of building.