ice dam with new roof and lots of insulation?


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Old 01-28-08, 09:11 AM
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Question ice dam with new roof and lots of insulation?

I live in MN and we've had a cold snap here followed by warmer weather. Yesterday there was a bunch of melting going on, and I noticed 2 water spots in the ceiling of our top floor (both spots are in the same room, about 5' from each other). The roof is under 3 years old, has a full ridge vent, no gutters and, within the last 4 months, I installed 16" of cellulose insulation. Before blowing this stuff in I added air channels to every space between trusses and also installed an angled piece to close off the area where the attic floor meets the roof. Sounds good to me....

What are my options at this point? We've been in the house for just under 2 years, so the roofing contactor is unknown at this point. Do new roofs come with some kind of warranty (besides the shingles), or am I past what would be the typical length of a warranty covered by the installer?

I have yet to get back up into the attic and see what I can see. Even if I plugged a few of the air channels when I blew in the insulation I don't believe that I would have seriously changed the air flow from the soffit vents. Maybe my logic is flawed? Any help is appreciated!!

Thanks!
 
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Old 01-28-08, 08:30 PM
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I don't know of many roofers who guarantee their work to be ice dam proof. Ice dams cause water to back up under shingles, which is not your normal sort of behavior. In areas of the country where ice dams are prevelant, some guys make a living by working through the winter clearing snow off of roofs so as to lessen the possibility of ice dams. Sounds like dangerous work to me.

You didn't say what pitch your roof is, but the lower the pitch the better chance of having an ice dam. Also, many manufacturers recommend the felt underlayment be lapped a greater amount when the pitch gets to be 4:12 or less.

Your old underinsulated attic was probably more efficient at melting the snow and ice gradually due to the heat loss.
 
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Old 01-28-08, 09:13 PM
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Raining in my attic....

Well, I got up into the attic and realized that there was nearly zero air movement. Inside it was basically raining from all the condensation that has built up, dripping onto the room with the wet ceiling . Once I removed the cellulose plugged baffles (everywhere!) and pulled the insulation from the edges you could immediately feel the difference. I know that I've lost some insulation value by running around up there and having to pull the piles away from the edge of the soffit, but now I'm sure that the qty of air movement will be sufficient. After everything was done it was obvious that the plywood panels were already drying out and there was no more dripping to be seen. For the next day I'll run a box fan just to maximize the drying effect. Basically, no ice dam, just my lack of experience doing something that's easy but still needs to be done correctly.

Thanks for your input!
 
 

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