I just installed a new gable fan to exhaust hot air from my attic. Due to unevenness in my studs and gravity pulling one side of the fan lower than the other, there are small gaps (ranging between 1/8" and 1/2") between the external-facing edge of the cylindrical fan housing and the studs that it's mounted to. The fan comes with black plastic covers that are supposed to prevent gaps but they're not thick enough to fill the gaps. So I'm getting a lot of hot air pushed through those gaps back into the attic instead of exhausted to the outside.
I'd like to come up with a good sealing solution. Here's some criteria that I think make sense:
- Can withstand years of fan vibration without breaking down
- Can fill gaps up to 1/2"
- Ideally, would help to dampen vibration and sound of the fan which can be heard (albeit softly) in my daughter's bedroom which is one story below the gable.
- Not an obvious code violation (I'm in California) or safety hazard
Here's a few ideas I've heard:
- wrap with neoprene (like a wetsuit)
- wrap the gap with flexible foam with a circular cross section, like a thin pool noodle
- one of above, and then secure with duct tape (or perhaps the high-end metal duct tape which might be more durable?)
- one of above, and then caulk (and if so, what kind of caulk?)
What would you do?
EDIT: here's a picture. I know that I'm supposed to fasten the black covers over the mounts, not under them, but I'm loath to go back and undo all this work and potentially ruin the black covers in the process.