ductwork through wall
Can someone tell me the proper way to seal ductwork going through an exterior wall? I am venting a microwave oven through the wall (wood siding). They hole is a bit bigger than the duct and I'm not really sure what you put around the duct pipe to hide/seal that gap.
I've looked at the big box stores and didn't see anything specific for this. Would you just use a flat piece of flashing material, cut a hole as close to the duct size as possible, nail that to the outside wall and chalk any remaining gaps?