I am going to make a hole for the AC pipe and it should also function as a fresh air vent. I searched around a bit and came across something about keeping the vapor barrier tight. Maybe it's not the end of the world, but some education is always good. When I finally drill, say a 120 mm hole in the wall and through the vapor barrier. Do you have to seal it or is it like, oh, it's not the end of the world...
