See that flap of backing up there? It has to go before I do anything further. It's at about fingertip height as I stretch above that crossbrace. (Lyman made the cut in the duct board and I won't be thanking him for it anytime soon. My fault, too. When I measured the cut in the board, I could have allowed a good three more inches for the top piece, and been working lower here at the bottom. I forgot about the cursed brace. Well, I'll know next time. Ha, ha, ha.)

And that damnable crossbrace. The vent opening is not framed well, which will entail building some little walls of duct board right around the mouth of the vent. This might be the only crummy detail in an otherwise very well-built house. And I want my Daddy.