 So today I'm working on an interior drill which is drilling the walls and filling them with insulation from the inside But I wanted to show you how interconnected houses can be. This is actually not one of the worst holes that I've seen here But I've got my blower running right now on this hose and then there's a fair amount of air coming out of this hole here Which you can't really feel but you can see When I start putting this in the front see where it starts blowing out right there That just gives you an idea of how interconnected the walls are in your house. So there's a stud that's running right in between here Yet, there's that much airflow going from one to the next. You normally won't see anything like this because I'm putting a fair amount of pressure on it from my blowing hose here But normally there is some leakage all the time and This is an interior wall, but the exterior walls do this too And this is part of why you get higher blower doors in older homes like this one