I just put my DC in an outside shed with 6' of 8" spiral duct between the two buildings. Future post on that. But for now, does anyone know if spiral duct is waterproof? Several feet of it is out in the weather.
If it is not, I will have to caulk the whole length. Yes I did avoid any fittings outside the buildings. I seem to remember seeing large spiral ductwork on the roof of commercial buildings.