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Thread: How to vent bathroom fan when you get 2 feet of snow on your roof

  1. #1

    Default How to vent bathroom fan when you get 2 feet of snow on your roof

    We bought a house in the Northeast Kingdom of Vermont that has a ceiling fan in the bathroom that is vented through the roof, using a flexible hose and a typical roof vent hood. However, we tend to get a lot of snow in the winter (last winter we twice had at least 2 feet built up on the roof before we shoveled it off). This causes the vent to be covered in snow, the moisture from the fan to condense and not be able to escape, so it then drips down into the bathroom whenever we turn the fan on, and sometimes when it is not even on, it will drip. We thought of two options to solve this: A) to build a 2-foot pipe above the roof (either PVC or stovepipe) and somehow support it on the roof - which is the tricky part - and connect the hose to that, or B) to vent through the soffit, and seal off the soffit ventilation holes for about 2 feet on either side of the fan vent to prevent moisture from re-entering the attic through the soffit. We'd rather not have yet another huge pipe sticking out of our roof, so we're leaning toward the soffit vent, but we have concerns about whether our idea of sealing off the soffit on either side will be effective at preventing moisture re-entry. Any ideas or advice would be welcome!

  2. #2
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007


    There is nothing kingdom about that section of Vermont!
    It's a frozen waste land! LOL
    Has the snow melted yet?
    If it has then the black flies have arrived!

    Venting through the soffit is probably your best option. Another part of your dripping problem may be the way the vent pipe is routed. THe warm moist air from the bathroom may be condensing in the cold vent pipe.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    I'd extend it on the roof and make sure I was using insulation around the vent pipe through the attic. Personally, I rarely use the vent in the winter, the added moisture just means the humidifer doesn't have to run as much. I do use it in the summer, as added humidity is not welcomed. I've seen some nasty soffit vents where bathrooms have been vented there. Would it be possible to vent out a gable end...the run may be longer, but if you insulate it, it may not be a problem. Rigid smooth metal vent pipe won't slow the air down as much as the corregated wire wound stuff. You might be able to place insulation around the pipe if it was layed on the top of the attic joists - this would keep it closer to room temp while it made its way outside, lowering the probability of condensation.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014


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