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  1. #1
    Join Date
    Jan 2011
    Posts
    32

    Default Venting a Bathroom Fan

    I am about to take a project on and wanted some advice.

    I am going to vent my new bathroom fan through the roof. I saw the kit at Home Depot, some flex line, a fitting, the roof vent and 2 zip strips. This is unacceptable to me for a cold climate.

    I want to use that 30 gauge circular ductwork straight up to the roof. Then from advice I read a while back, coat it in spray foam to prevent condensation.

    Another question is if anyone offers a nicer bathroom fan roof vent. Anything I can find seems flimsy.

    Thanks for any advice!

    Thanks!
    - Ehren.

  2. #2
    Join Date
    Oct 2008
    Posts
    116

    Default Re: Venting a Bathroom Fan

    I have this kit in a new bathroom, and a second in the original house built 23 years ago. Other than the fact that I did use better clamps and better (insulated) flexible duct when working in both bathrooms, I've not had any problems with the metal vent that mounts on the roof. Even when I had my roof re-done I was prepared to replace the old one but the contractor said it was in good condition.

    Good luck.

  3. #3
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,969

    Default Re: Venting a Bathroom Fan

    Go to the roofing dept (or better yet a roofing supply co) to get better parts.

    You can spray the foam insulation over any type of pipe, the more rigid the pipe the easier it is to spray. Jacket insulation will work too.

  4. #4
    Join Date
    Jan 2011
    Posts
    93

    Default Re: Venting a Bathroom Fan

    smart of you to question what The home dump has to offer. I agree with Mr Houston about going to a roofing supply house. There you will have better material to choose from.

    Don't forget to install a timer on that fan. Not only does the fan dry the bathroom, it also must dry the inside of the duct, and can only do that if it runs long after you left the bathroom.

  5. #5
    Join Date
    Sep 2009
    Posts
    9

    Default Re: Venting a Bathroom Fan

    Just installed a bathroom exhaust fan this past weekend. I ran the duct to the side wall (through the attic) as it was only 3.5 feet and I sloped it about two inches toward the outside vent.

    I did use rigid 4" ducts rather than the flex ductwork that they sell in the venting kit. The ridges in the flex duct can trap moisture and cause problems.

  6. #6
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Venting a Bathroom Fan

    Quote Originally Posted by ironman70 View Post
    Just installed a bathroom exhaust fan this past weekend. I ran the duct to the side wall (through the attic) as it was only 3.5 feet and I sloped it about two inches toward the outside vent.

    I did use rigid 4" ducts rather than the flex ductwork that they sell in the venting kit. The ridges in the flex duct can trap moisture and cause problems.
    This is a good install.
    I would also recommend covering the ducting with an insulated covering for winter temps.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  7. #7
    Join Date
    Sep 2009
    Posts
    9

    Default Re: Venting a Bathroom Fan

    Quote Originally Posted by canuk View Post
    This is a good install.
    I would also recommend covering the ducting with an insulated covering for winter temps.
    Sorry, i should have mentioned that. I did wrap the duct with foil-faced insulation. Need to pick up some more as one as i didn't have enough. I also need to spray foam the opening where the duct exits the attic as it is about an inch bigger than the duct.

    Note to self...don't buy a 4" hole saw for a 4" duct. It doesn't fit...then you'll have to go back and buy a 5" and waste $25.

  8. #8
    Join Date
    Nov 2011
    Posts
    1

    Default Re: Venting a Bathroom Fan

    Quote Originally Posted by ironman70 View Post
    Just installed a bathroom exhaust fan this past weekend. I ran the duct to the side wall (through the attic) as it was only 3.5 feet and I sloped it about two inches toward the outside vent.

    I did use rigid 4" ducts rather than the flex ductwork that they sell in the venting kit. The ridges in the flex duct can trap moisture and cause problems.
    I've not had any problems with the metal vent that mounts on the roof. Even when I had my roof re-done I was prepared to replace the old one but the contractor said it was in good condition.

  9. #9
    Join Date
    Sep 2009
    Posts
    9

    Default Re: Venting a Bathroom Fan

    Are you talking about the duct work itself or rather the actual vent that mounts to the roof?

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