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insulating bathroom exhaust fan

2 years ago

I’m looking for suggestions. My exhaust fan is about 2’ away from my wall. I have two 90 degree rigid elbows. I was wondering the best way to insulate the pipe. The first elbow is held in with closed cell spray foam. Would it be better to wrap fibreglass insulation around the elbows and tape it or has anyone ever used foam in a can? The other option is to scrape out the spray foam and use insulated flexible pipe. I’m worried if i use rigid pipe and i ever need to replace the fan i’m going to end up having to cut out more ceiling to slide the fan out.

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Comment (1)

kudzu9
2 years ago
last modified: 2 years ago
1. Avoid using the flexible, "accordion-style" pipe if at all possible: since it doesn't have smooth walls it can accumulate dust and mold more easily.

2. For insulation of the pipe, get HVAC foil tape and use it to seal all the joints; it's about the same dimensions as regular duct tape, but more tenacious and won't deteriorate over time. After you have sealed all the joints, you can wrap it with fiberglass batting and tape it to stay in place around the pipe. When I've done this, I've not only taped the seam that runs parallel to the pipe, I've put a wrap of tape all around the circumference every foot or so. Taping the insulation on will be easier and you will get a better result if you have foil-faced or paper faced batting with this layer on the outside.

P.S: I've never tried spray foam, but it could be messy, and would be a pain if you ever needed to get at the ductwork.
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