Deicing Cables - Do they Work?

Old 10-08-05, 10:15 AM
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Deicing Cables - Do they Work?


I live in Maine, and last winter the icicles got so bad over my daughters bedroom window that they pushed the seamless gutter about 6" outward. I'm looking to avoid the same issue this winter, and I was hoping someone could advise if deicing cables work well in this area.

As a little background, the front of my house faces south-east, so it gets lots of sun, and althought some icicles do form, they normally melt-off, and have not damaged the gutters.

However, the back of the house doesn't get as much sun obviously, and the icicles there tend to be a lot bigger. The only area that the gutters have been forced outward is above a double-window (80"W) in my daughters bedroom.

I don't think the attic is the problem (12" fiberglass insulation), but rather heat-loss out the large window. I have not seen any roof damage caused by ice-dams.

I have GFCI outlets available outside on the back deck, and I was hoping to power the deicing cables from there.

Any thoughts, comments or recommendations would be appreciated.


Old 10-08-05, 10:26 AM
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Deicing Cables - Do they Work?

I have used them and they do work. I had no choice but to use them under certain conditions. You should not rely on them, since proper ventilation and insulation will solve the real problem.

I recognize the problems that gutters cause by preventing drainage. Even at -20 you can get drifting and surface melting on a dark roof and a build up of ice that has no place to go.

If you have the right situation, a snow puller is the best thing if you use it periodically.

Old 11-03-05, 02:23 PM
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I had them too

Here in MN they worked for me. I installed mine down the valley that had the largest build up and ran them into the gutter.

I ran out of cable before I ran out of gutter, but where there was cable my ice buildup was minimized.

I did not turn them on all the time. Only when I saw a warm day coming and figured that snow would melt and re-freeze at night.

Dick is right though, there is a reason that you are getting ice damns.

Also, I don't recommend using the cable & a roof snow remover.

That could be a shocking situation...
Old 11-25-05, 04:29 AM
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Ice dams are created by the lack of ventilation in the attic. It would definitely be cheaper in the long run to fix the ventilation in the attic then having to pay electrical bills for the cable.

Under certain conditions they may be the only solution, but check your ventilation first. You need venting at the soffits and then near the roof peak to help equalize the temperature in the attic space.
Old 01-01-08, 12:48 PM
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Ice Dam

1st a quote from Popular Mechanics Homeowners Clinic:

"First, the only certain cure for ice backup, short of removing your gutters, is to use heat tapes. This keeps the ice from backing up under the shingles, causing water leaks."

Properly installed the heat tape does not allow the gutter and the first 12" est of roof to freeze (drain pipe must also be heated). As the directions state they are not de-icers. They "warm" the surface where the wires touch and the snow melts as it hits the wire, thus preventing sticking or worse freezing in the gutter where the ice dam is created. This might mean keeping the power (low voltage to the wire) on for several days until the snow melts(further up the roof, rain,etc.) I use a sentry light on the switch to remind me that it's still on.

In northern MA, I've seen many homes with the last three feet(approx) of roofing replaced with smooth metal and some with, and without gutters.

If you forget to turn on the heat tape or your away, which almost will certainly happen over the years, you can protect your roof and the area under the roof you DO NOT WET, you can remove the first 3-5' plus of roofing material, depending on the roof pitch and replace with "Rain and Ice Shield", or "Moisture Guard by Tamko, then replace with your shingles, etc.

Removing the snow before it freezes is a good solution for eliminating the snow on the roof from melting with no place to go but "backup" the roof and under the shingles, seams, etc., but this DOES NOTHING for the snow that accumulates in the gutter which also freezes solid, and will stay frozen much, much longer than any on the roof surface.

There is no removing snow where the heat tape is located. They are held in position only by clips that if disturbed or moved eliminates their purpose.
Old 01-01-08, 06:07 PM
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The freezing is not all of the problem. Everything outside will freeze in the winter. The problem is freeze-thaw-refreeze. That is caused by poor construction practices. There should be an air block at the end of the ceiling joist and the heel of the rafter should be high enough to get the full R-value of the insulation all the way to the edge of the wall. Usually, the insulation is just pushed out there and air from the outside gets inder the insulaiton making the room cold and heat from the room ceiling gets out and melts the snow right over the top plate of the wall. That causes the freeze-thaw-refreeze cycle and instead of snow it turns to ice and icicles. It can be remedied without heat strips but it will require some more work.


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