Our range hood looks like this: Range hood

I discovered a ton of freezing cold air coming from the top of the hood recently. I took a ladder, and it looked like this:

Big hole 1 Big hole 2

Cold air just pours through the opening.

Any suggestions for how to seal up the holes in the wall? Keep in mind this is not visible unless you are on a ladder, so something that is quicker/easier will win over something that looks pretty. Also, I'm not interested in pulling out the piping to wrap something around it, if at all possible, as that dramatically increases the level of complexity for me.

Additionally, is there any risk to sealing up the top of the range hood, or does it need to be left opened?

  • How about one more picture from outside where the hood vent exits the house? Do you have s good damper that stops back drafting?
    – Kris
    Feb 10, 2018 at 0:40

1 Answer 1


While I'd ordinarily reach for polyurethane spray foam, that may not be the best idea on a range exhaust duct that could conceivably have a grease fire inside it at some point in time.

Stuffing the hole/gap with rockwool would be relatively fast and easy, and fire-resistant (more than fiberglass, anyway.)

Slapping a scrap of drywall or cementboard over the open top area might further help, but you might need to dress up the edge of a sheet put there, as it would be visible from the floor.

But it slowly occurs to me that they do actually make a "fireblock" spray foam, and that would be just the ticket here, I think.

  • 1
    This worked. It was messy as hell, given the angle, and I ended up getting orange insulation on the ceiling which I have to now repaint, but the amount of cold air coming in is near zero now.
    – Jason S.
    Feb 11, 2018 at 17:09

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