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hazmat
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Do Ice damns always mean damage?
01/21/03 11:04 AM
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We've got ice damns on the south side of our house. Does it mean we are going to get damage? None present yet that I can see.
Will a snow rake do any good now that they're set up? Or is it too little too late?
Hazmat
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s1120
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Re: Do Ice damns always mean damage?
[re: hazmat]
01/21/03 01:46 PM
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Same boat here. BAD ice jams. Its so sold that there going nowere.
Paul Bradway
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beenthere
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Re: Do Ice dams always mean damage?
[re: s1120]
01/21/03 03:07 PM
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Ice dams won't do damage unless the water that backs up behind them gets high (or deep) enough to run under the shingles and down your walls and into your insulation or through the plaster or drywall. Once detected that way, a lot of damage is already done.
I use a technique someone taught me where I create an opening in the ice to let the water run out so it cannot build up behind the ice. Of several ways, there is salt(sometimes hard on the gutters and lawn), hatchet or hammer (sometimes hard on the shingles), or melting the ice either with warm water or with an electric heated tape or cable. If I use the warm water, I run it through the hose on a stick to reach the ice at the bottom edge of the eaves. I then let it run to melt the ice from the bottom up, until it is gone. The temperature of the air makes this a bit tricky, but it is amazing how fast the ice will melt. Until more snow melts to make more ice, this can work pretty good. Another way is to use a long 1/2 plastic pipe on the end of the hose to get the water to the ice dam. Watch out for a gush of water to come out when you break through the ice dam. 
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Stoneheartfarm
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Re: Do Ice damns always mean damage?
[re: hazmat]
01/21/03 05:23 PM
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I have to agree, ice dams do not necessarily mean you will have damage, for the very reason beenthere has given. But, it does set you up for trouble. Some homes never seem to have a problem with ice dams and others seem to have massive dams every year. Some times it is just a matter of weather and everybody winds up with ice dams. There are a number of steps that can be taken to prevent them, but once you've got them, there are only a limited number of alternatives.
I've neer heard of the garden hose trick, so I'll have to keep that one in mind. What has worked for some people is a sock filled with rock salt. You throw the sock up on the roof so that it lays across the ice dam and melts a trench through it to let the water out. Not too easy on the lawn and probably not the best thing for the roof, but I'm told it works.
Steve
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wingnut
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heat tape!
Before any more ice dams up.
it's a shame that common sense isn't
http://www.dahlhausminiatures.com
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EJB
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I have read that if you are going to use the salt on the roof, it best to use calcium chloride, not the regular rock salt you buy. Supposed to be easier on the shingles etc. Both are usually available at the stores.
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Boondox
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Re: Do Ice damns always mean damage?
[re: hazmat]
01/24/03 03:04 PM
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Not always, as Beenthere pointed out. I've found that raking the snow off the last three feet or so of roof minimizes the buildup of ice...if you stay on top of it. I think the portion of the roof that extends beyond the walls of the house gets colder, so any water melted from above the heated (and in our case poorly insulated) portion of the roof runs down and refreezes. By raking the lower roof it never seems to refreeze till it drips off the roof and hits the ground. Just a theory but I haven't had ice dams since I became a raking fanatic. 
Pete
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Stoneheartfarm
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Re: Do Ice damns always mean damage?
[re: Boondox]
01/26/03 12:35 PM
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and in our case poorly insulated
Maybe, maybe not. You might want to increase the attic ventilation. Ice dams are a combination of heat loss into the attic and not enough ventilation to keep the roof cool. Snow melts on the roof, runs down to the eaves (which are cooler) and freezes. If you can cool the roof through increased ventilation, it should reduce or eliminate your ice dam problem.
Steve
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RobS
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We have a nice ice dam starting on only one section of our new house. I checked the attic and I can see daylight from the soffit vents so I know it's not a matter of heat rising through the ceiling. I think ours has to do with the sun. This section is getting some mid-day sun on the roof, but not the gutter. I think the snow is melting on the shingles then re-freezing in the shade of the gutter. I'm not too concerned about it but will watch it over the next warm-up 
Rob
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Re: Do Ice damns always mean damage?
[re: RobS]
01/27/03 08:46 AM
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We have a nice ice dam starting on only one section of our new house.
Just curious what is the pitch of the roof? This doesn't answer the question but I was wondering if the higher the pitch the less chance of ice dams forming.
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Worksmart
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Re: Do Ice damns always mean damage?
[re: StanleyinMd]
01/27/03 09:20 AM
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Stanley - I would say no from personal experience. My Cape Cod roof is a steep 8 or 10 on 12 pitch. I got some nasty dams shortly after I moved in in '97. Never got any interior damage, luckily. I am now a raking fanatic too. Chuck
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RobS
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Re: Do Ice damns always mean damage?
[re: StanleyinMd]
01/27/03 09:23 AM
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Our roof is quite steep at 14:12. I was surprised to see the ice dam but again, I'm not too worried about it. For there to be damage melt water will have to travel up under the shingles. That's where the steep pitch should really help.
Most places the snow isn't even staying on our roof. This particular spot is where two roofs intersect forming a valley. It's collected more snow there than anywhere else
Rob
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Boondox
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A neighbor got great results by sealing his attic with those foil-covered foam sheets from one end to the other, and using spray foam in the corners to seal the house heat out. His attic is much colder now. Sounds a bit like what you were describing.
Pete
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beenthere
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Re: Do Ice damns always mean damage?
[re: Boondox]
01/27/03 11:31 AM
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If I understand you right this sounds like your neighbor put a vapor barrier (foil-covered foam sheets) on the cold side of the attic insulation. This will make for some very wet, and ineffective insulation under the foam sheets if that is the case.
Maybe I missed the true picture.
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cowboydoc
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Re: Do Ice damns always mean damage?
[re: beenthere]
01/28/03 09:40 AM
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There is also a product that you put on the roof like tar paper. I can't remember the exact name of it. But if you put this on you never have to worry about ice damming and the resultant water down the walls.
We had this problem at my office building. Had to tear up the shingles 4 foot up all the way around and put that material down. Since then we have never had a problem.
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hazmat
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Re: Do Ice damns always mean damage?
[re: cowboydoc]
01/28/03 10:04 AM
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The weatherman says 40 deg & raining on sat. I'll Probably know then if we've got any damage.
Hazmat
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Stoneheartfarm
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Re: Do Ice damns always mean damage?
[re: RobS]
01/28/03 11:56 AM
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Rob,
Yes, sunlight and general weather can do it too. If it warms above freezing during the day and then drops to below freezing at night, you stand the chance of starting an ice dam, no matter how well ventilated or insulated you are.
There are basically 2 cures that I have seen for this situation. One, Cowboydoc has already mentioned, and this is to use an ice and water dam type product. The other is to use 2-3 feet of sheet aluminum between the bottom shingle and the end of the eave.
When I roofed the cabin. I ran with the sheet aluminum 3' wide. On the house, we went to ice and water dam laid under conventional shingles. Neither has leaked. The house has very little heat leakage and so we haven't had much real ice. The cabin on the other hand had a lot of it. (Both heat leakage and ice). The only problem with the aluminum is that ice dams will tend to come off in a solid lump, and can destroy (or kill) anything they hit. (mini icebergs). This is also why I have been cautious of metal roofs on buildings, although no one I've talked to has had any problems.
Steve
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Argee
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Ice dams are usually caused by inadequate insulation where the eave wall meets the rafter or truss. There is too little room there to stack enough insulation over the plates of the wall. Or (As Steve pointed out) there is so much insulation crammed in to that little space that it blocks the air flow from the eave vents. A roof has to breathe, if it doesn't you also stand the chance of your sheathing rotting out. The heat from the house escapes at that point warms the underside of the sheathing and melts the snow on the roof above. When the temperature dips at night it freezes. Over many days and nights of this action it creates a dam thus allowing water to back up under the shingles. Sometimes, due to the poor design of the roof or trusses it is unavoidable. In those cases I would install ice and water shield up the entire roof. If I were building a new house I would install trusses with energy heels to allow for additional insulation. I have energy heels on my trusses which allowed me to install over a foot of insulation directly over the wall plate. The snow that goes on the roof at the first snowfall of winter is still there in the spring without forming any ice. I also installed ice and water shield over the entire roof for peace of mind.
Argee
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Worksmart
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Re: Do Ice damns always mean damage?
[re: cowboydoc]
01/30/03 09:23 AM
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Cowboydoc - "Ice and water shield" is the common name used in my parts.
Standard practice is 3' along lower edge of roof. When I had my house re-roofed 2 years ago, my roofer has now gone to 6' wide coverage of ice and water shield.
Chuck
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Argee
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Re: Do Ice damns always mean damage?
[re: Worksmart]
01/30/03 04:05 PM
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Standard practice is 3' along lower edge of roof.
Actually common practice and code for that matter is 3' from where the eave wall meets the roof. Dependent upon your overhang that could be 3' to 6'.
Argee
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