My house is in an area which often gets -30c winter days and 30c summer days.

It's shaped like this (note that ventilation holes are also the same on the other side of the house):

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Note that the roof is totally straight, not curved. On the 2nd floor which is shaped like an A, in winter the house easily gets cold and in summer, it easily gets hot which, IMO, probably signifies a lack of insulation or some kind of ventilation problem maybe.

The main issue is that almost every winter, water is leaking from the roof, especially in the beginning of the spring, where an ice dam is already formed at the end of the roof, near the gutters.

(Always refer to above picture for colored items mentioned below)

In March, I went in the soffit area (the last 3 feet below green line, sorry, there's probably a term for this area) and the water leaking is indeed aligned with the ice dam, which is in center of the roof. Many 2x6 rafters were soaking wet, actually DRIPPING water. Most of this is going inside my house through the plywood and sheet rock :(


There is insulation wool everywhere between the 2x6 rafters from the green line to what seems all the way to the attic and this is all across the entire roof. I've been told by somebody recently that this should not have been built like this as it prevents hot air from escaping through the roof ventilators as the air can never leave below the green line, causing ice dams in the winter and when spring comes, it's hot enough to quickly melt and drip inside of the house. NEED EXPERTISE ON THIS PLEASE.


All the vents on both sides of the house are OPEN and wind is going through, I've verified this by entering the last 3 feet, which is outside of the house. I have access to both the front and back soffit areas. I've been told that when roof ventilators are installed, all the side vents of the house should be shut/closed to prevent disrupting the normal ventilation process of hot air going up and escaping through the roof ventilators. NEED EXPERTISE ON THIS PLEASE.

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1 Answer 1


With two much insulation the vents can not do there job making sure there is an air flow path from the soffets to the ridge / ventilators needs to be the first repair / change. Even with good ventilation with cold temps you have may have issues that require Ice & snow melting heat tape. I used heat tape on my home and under some gutters to prevent ice dams. It sounds like. You need to clear some insulation to allow the vents to work. Then if the ice dams continue heat tape will be needed. Both poor ventilation and ice dams can create damp and or wet areas you describe, I would add the heat tape in the ice dam area this summer but that can cost a bit to have a circuit installed and the tape put up. Moving insulation can be a nasty job but dosent cost and may do the job If rafters are wet at locations other than the ice dam.

  • That's what I thought. I cannot believe a roofing contractor built my roof like this. BTW, I cannot sue them, because the roof was literally done 1 year before I purchased this house. The previous owner recently told me the roof ventilators were ADDED while the roof was redone. My best guess is that they wanted to make more profit, so they sold the previous house owner 2 roof ventilators but goofily (or crookedly to make even more money) insulated all the in-between rafters, preventing the air flow. Damnit. Thanks for confirming what I thought. Now I have to remove the insulation.
    – that-ben
    May 24, 2018 at 17:35
  • Wait, when you said "Moving insulation can be a nasty job but dosent cost and may do the job If rafters are wet at locations other than the ice dam." can you further explain? Because the only places the rafters were damp was in the center of the house directly above the ice dams.
    – that-ben
    May 24, 2018 at 17:38
  • Sure, insulation covering the soffit vents will be in an corner of the roof Depending on pitch it may be just an arm length if a shallow pitch roof it may take a tool to reach in, dusty or fiber glass that's what I mean by nasty. Next rafters wet , if most of the entire attic has wet dripping problems the issue is ventilation. If the only area that is wet is under the ice dam then the ventilation is fine, a heat tape is probably needed to eliminate the ice dam. Once ice builds the water backs up under the shingles and that water finds it way in. Hope that clarifies what I was trying to say
    – Ed Beal
    May 25, 2018 at 1:23

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