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Two Ice Dam Questions

pico_project | Posted in General Questions on

This February will be one year in our remodeled house. It’s a 1955 single story ranch with a low pitch roof in northern Michigan. I took extra care to air seal the attic floor before reinsualting and overall have been very happy with the lack of ice forming on the roof. 

However, recently we received a lot of snow. Enough to cover the kitchen vent which is a straight up shot from the stove up through the roof — maybe 1/4 of the way down from the ridge. The vent is melting the snow and it’s forming a pretty large icicle section straight down over the facia (no gutters). 

Today the vent looks somewhat clear of snow, even though the rest of the roof has a thick layer. Given this hasn’t happened yet with light snow I’m assuming this ice was formed from melting the snow enough to clear the vent? Or is this a common issue?

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Next question. The north side of my neighbors house is visible from our kitchen window. She has huge ice dams. Today large icicles were maybe 1ft from the ground. So we’re talking 6-8ft long. She has a heat coil installed near the roof edge but with the colder weather it’s not working. 

I have noticed exhaust coming out her east gable end and have concluded that someone installed the furnace in her attic space and it’s literally melting the entire roof. As mentioned, the side I see is north facing and she rarely has snow on the roof. 

She moved there a year before we moved in to our place. I’m not sure if she had it installed or it was existing. 

Anyway is it possible for her to go after the HVAC company that installed the furnace? Up here it seems very negligent to have done that. If not —out of curiosity — is there any way to remedy it without pulling the roof off and adding exterior insulation? Specifically, would adding interior insulation on the bottom of the roof deck do more harm than good without exterior insulation on top of the roof deck? I’m assuming relocating the furnace could be a cheaper option in the long run?

I wanted to hear some options on it as I’m pretty sure it’s stressing her out. 

Thanks!

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Replies

  1. Expert Member
    Akos | | #1

    No easy answer here. First step would be to get somebody with a duct blaster and seal up the ducting in the attic.

    Attic spray foam is a big cost with ROI of pretty much never. At that point you are better off to run heat rope on the roof to limit icing.

    1. pico_project | | #2

      Thanks for the reply. She has heat rope, but it doesn't seem like it's enough to limit the ice. This is all observation from my window. Not sure if she gets leaks inside or not.

  2. MartinHolladay | | #3

    Piko,
    Your description of your "kitchen vent" is unclear, but I assume you're talking about the exhaust duct from your range hood fan. Ideally, that exhaust duct should terminate on an exterior wall. If you have no choice but to run the duct through the attic, it should terminate at the gable wall. If your house has a hipped roof (without a gable), the kitchen range should be located at an exterior wall rather than an island.

    But these rules for kitchen design probably don't help you, since the exhaust duct apparently rises vertically and penetrates your roof.

    1. pico_project | | #5

      Well we haven't done anything to the kitchen yet, so that is something to keep in mind. Thank you. Although the roof is new. Haha.

      We do have a hipped roof. It's a galley kitchen. The only exterior wall is south facing and is the front of the house that faces the road. We don't have a ton of wall height. How far should the vent be from the soffit so it doesn't just suck hot moist air up into it?

  3. walta100 | | #4

    My wild guess is the neighbor turned off the heating coils on her roof because they were using too much electricity.

    Walta

    1. pico_project | | #6

      I believe I still see the wave of the cable on her roof through the snow. I'll try to get a photo when I get back home. It's bad far the worst case of ice damning I've ever seen. But I also don't know anyone with their HVAC in the attic here either.

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