I was removing some ancient hanging cabinets in my small laundry room when I found an old vent of some kind. It had been completely hidden behind the old cabinetry. My dryer vents out through the roof so I want to close and seal this opening, especially before it gets really cold.
I believe the gist of it is that I fill the hole with insulation and put some drywall on the inside. I then cover the outside with some sort of aluminum plate or plywood. Any experts out there have input as to choice of insulation or external covering? I think the box is too big for the kind of spray foam one would use around pipe holes. I have stucco on the outside of my wood house. Also, should I remove the inner walls of the box or just leave well enough alone?