Ice Dam

After a second huge ice storm since I moved here (Iowa), I again have water coming in the house, due to a giant ice dam that has formed in one of the valleys of my roof.
I had Servpro come out to chip away the ice and handle the water damage. They told me they thought the water/ice was flowing off the upper roof onto the lower roof and freezing in the valley. They suggested I get gutters on my upper roof to fix the problem in the future, but looking at the gutters on my lower roof, I can't imagine they would help much.. They are completely frozen over. They did say that we have had two of the biggest ice storms in 7 years and that it shouldn't happen all the time. The problem was that there was so much ice, it built up higher than the moisture barrier that runs up the side of the house from under the shingles.
Does anyone have any advice on how I can prevent this problem in the future?
Thanks, Dan
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Ice dams are usualy from a poorly insulated attic or air infiltration from below or a lack of venting making the attic to warm. Your gutters may not have enough pitch to drain fast.
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Agree that lack of insulation/ventilation is your core problem. The bandaid approach is to install heat cables. The only way a gutter will work in this situation is if it has heat cables in it. Cables are a PITA since they don't last forever and potentially present a fire hazard, but they will work. Trouble is, it might be too late this winter to get them installed.
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My gutters did this until I increased the down pitch, But I think you need insulation air infiltration help, go to R60++ . A Blower Door test can tell alot.
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ransley wrote:

Ice dams may "usually" be caused by poorly insulated attic etc. but the storm lagman is talking about is producing "unusual" ice dams.
I've been in the same ice storms as lagman. The liquid water is coming primarily from the sky (freezing rain) NOT from snow melt on the roof due to "poorly insulated [or ventilated] attic". The gutters are clogged NOT because of poor pitch but because they were filled with sleet by a previous storm and, due to temps, were never allowed to melt so there are blockages in sections.
lagman, you mentioned your ice dam was at a roof valley and the build up was higher than the moisture barrier (ice and water shield) extended. The ice and water shield should go all the way up the valley, centered, so it's 1 1/2 feet on either side of the valley and, on the eaves, at least 2 feet uproof from where the wall intersects with the roof.
One thing you might check is that the gutters are tilted so that, when they are filled up, they dump runoff away from the house -- that would be the "roll" of the gutters as opposed to the "pitch". So, in situations like we've had in the last 2 weeks, when the gutters are clogged, the freezing rain is dumped away from the house and is not trapped between the gutter and roof edge to form a dam. That way, you may get water closer to your foundation than you'd want (do you have drain tiles and a sump pump?) but you're less likely to get an ice dam.
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Thanks for the reply. I will try tilting the gutters as you suggested, but just for piece of mind, I'd like to have some type of melting mechanism in place in the valley. I have heard mixed results from using heat tape. One person suggested using something called "Ice Viper". Its basically a long bag filled with melting agent that you put on your roof (it claims to contain chemicals that will not harm your roof or siding).
In either case, what is the best configuration to use? Should I lay the Ice Viper/heat tape straight down the valley line? You said the moisture barrier will run centered along the valley with 1 1/2 ft on each side.. So maybe I should put them a foot or so on each side of the valley.
Is the 1 1/2 ft on each side of the valley and 2 feet extended up the wall pretty much standard for a house built in '93? It would make sense.. The ice dam spanned about 3-4 feet across when the water was coming in.
Thanks, Dan
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wrote:

I had a similar problem in my previous home, also with a valley. It happened rarely. I got on a ladder and tossed large amounts of rock salt onto the area twice a day for a few days until it all melted. Unless the same strange weather pattern reoccurred, the damming would be gone for the rest of the winter. And, the salt didn't hurt the roof. Might've been calcium chloride.
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On Wed, 12 Dec 2007 14:28:07 GMT, "JoeSpareBedroom"

You can buy this calcium chloride stuff in hockey puck form, making it easier to throw up on roofs, and that's what I do for my problematic valley.
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lagman wrote:

Dan, I'm not sure that "Ice Viper" offers any more advantage in dealing with an existing ice dam than the homemade "calcium chloride in panty hose". For a description of that see:
http://www.thisoldhouse.com/toh/skill-builder/0,,211604,00.html
Here's what it says:
-------------
"If you live in a cold, snowy region, you already know about the damaging effects of ice dams. The gutters clog up with ice, then water runoff from the roof gets trapped by the dam and eventually backs up the roof, travels under the shingles, and leaks into the house.
"While a permanent fix for ice dams usually requires increasing the insulation, sealing, and ventilation in the attic, there is a simple way to diminish the damage after the dam has formed.
"Fill the leg of discarded pair of panty hose with a calcium chloride ice melter. Lay the hose onto the roof so it crosses the ice dam and overhangs the gutter. If necessary, use a long-handled garden rake or hoe to push it into position.
"The calcium chloride will eventually melt through the snow and ice and create a channel for water to flow down into the gutters or off the roof."
-------------
Note that you should put the filled hose leg "so it crosses the ice dam", i.e. perpendicular to the dam so you create a channel for the liquid water to run off the roof.
As far as where you want to put the melting agent (chemicals or heat): Remember, you do NOT want to create MORE liquid water above the potential ice dam; you want to either 1) inhibit such liquid from forming (for example, more attic insulation and ventilation to inhibit roof snow melt) or 2) as in your present case, if you are unable to prevent the liquid water (rain), give it a path to quickly run off your roof.
So, with an EXISTING ice dam, I'd be VERY skeptical about putting something like the "Ice Viper" above the dam -- you don't need MORE liquid water running down the valley.
As a PREVENTIVE, either the heat tape (I have ZERO experience with heat tape/cable) or the pantyhose/"Ice Viper" down the length of the roof valley, I don't know but I'd want to do a LOT more research on both safety (for example, risk fire and/or damage to roofing materials)and effectiveness before I'd do that.
By the way, as far as "tilting the gutters" goes: I didn't mean to imply that you can make the necessary adjustment (if it's needed) now with all the snow and ice filling them. If you find that they do need to be tilted so that any overflow goes away from the house, I'd call a gutter installation/repair company to find out when they could be corrected safely.
Best of luck, Dan. Believe me, I feel your discomfort. :)
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I finally broke down and had a roofer come out and give me an estimate. I asked him to evaluate the problem I have already had and tell me if there is anything I can do to the roof.
He said he could pull some shingles off and put a good moisture barrier up there, then where the roof meets the edge of the house, extend the water barrier up the side of the house. He said he could do both for $800 to $1000., or just the moisture barrier under the shingles for $400-$500. He of course suggested I do both He will not offer me a guarantee the roof won't leak again higher up, but claims this is something that should be done given the design of my roof.
Does this sound reasonable, or are they just trying to take advantage of someone who is desparately looking for a solution?
Thanks, Dan
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wrote:

What he's suggesting certainly wouldn't hurt. But, what about insulation and ventilation? Is there enough insulation in the attic to keep it nice & cold? What about vents in the eaves? The idea is to keep the snow from turning into ice. Keep it fluffy.
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lagman wrote:

Hi, Dan. I'm not sure what you mean by "where the roof meets the edge of the house, EXTEND THE WATER BARRIER UP THE SIDE OF THE HOUSE". Are you talking about under flashing? I assume you're talking about using something like Grace Ice & Water Shield or Certainteed WinterGuard; those products are UNDERlayments and not supposed to be exposed for any length of time to sunlight -- they are applied to roof decking under shingles or under flashing or behind gutters or behind drip edge, etc.. Additionally, they require DRY decking (or whatever substrate) and TEMPERATURES well above freezing (at least 40 degrees F) when they are applied. Read about WinterGuard at:
http://www.certainteed.com/NR/rdonlyres/BE66DA16-D029-4D5B-A86D-8257A5CCF205/0/ESR1492.pdf
Here's info on the Grace Ice & Water Shield:
http://www.graceathome.com/pages/downloads/GIWS-060P.pdf
Is the roofer planning to do the work now with winter temps and conditions? If so, how? Did he talk about the likely need to replace some of the decking; if so, how much and how -- particularly since your problem involves valleys?
As far as the cost, as a mere homeowner (not a roofer), depending on HOW the roofer intends to do the job, it doesn't seem outrageous. In fact, depending on how the work SHOULD be done, it seems to me that it may be low; so I'd want to be sure that what the roofer intends to do is "good practice" and likely to be effective.
Dan, I'm afraid I don't have the expertise to properly answer your question but I can suggest where you might find some experienced roofers who may be willing to suggest possible options -- but don't expect them to be very "precise" as far as what roofers should charge -- highly variable due to location, weather, etc. I recommend you register and post your question(s) at Roofing/Construction Questions forum at:
http://www.roofing.com/forum/forum-2.thtml
Best of luck, Dan.
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When I say "Where the roof meets the house", There is a room on our second floor that "juts" out from the roof. Here is a (small) picture of our house:
http://thumbs.trulia.com/pictures/thumbs_big/3889/1041093889_337986646-1850-Litchfield-Dr-Hiawatha-IA-52233.jpg
The problem area is where the garage roof meets the side of the house (there is about a 45 degree angle between the garage roof and the house, this is where the ice dam formed and where the water leaked in).
As I understand it, here is what he plans to do:
-Take off original shingles all along the valley. -Put Winterguard all down the valley. He said the stuff is 3 feet thick. -I remember him mentioning something about step flashing. I think he wants to add some down the slope of the roof where the roof meets the house. - He mentioned using some sort of roofer's tape to tape off the top of the flashing so ice can't get in back of it. - I think he said something about adding a special piece of siding somewhere.. - Match the shingles and replace.
He didn't say anything about replacing any of the decking, just making what is up there water tight.
Those were the main things, and I have a written estimate. He did say he would be able to do it in January unless we keep getting snow.
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lagman wrote:

http://thumbs.trulia.com/pictures/thumbs_big/3889/1041093889_337986646-1850-Litchfield-Dr-Hiawatha-IA-52233.jpg
Dan - What you say the roofer is proposing sounds reasonable to me -- but, as I said, I'm a homeowner (with 2 valleys on a more simple roof than yours), not a roofer. Again, I encourage you to post a description of your problem and the roofer's proposal on the Roofing/Construction Questions forum at:
http://www.roofing.com/forum/forum-2.thtml
The roofers there seem knowledgeable and helpful to homeowners.
I WOULD be concerned about the weather and temperature conditions under which the roofer intends to do the work. To properly seal (and that's the whole point of WinterGuard) it must be put on a dry deck above 40 degrees F. If it were me, I'd talk to the roofer about that before giving him the go-ahead.
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