Thoughts on roof ice melt cables

scrynFebruary 20, 2007

We have an old farmhouse with a asphalt shingle roof. We always get an aweful ice dam on our second story on an "inside" corner. (hard to explain, sorry!) this must have been a problem before we bought the house because we saw, when we went up to fix the dam one year, that a previous owner had added more venting to the soffit and poked some "drainage" holes at some point.

This is the fifth year we have been in the house. We had the worst issues the first year and it hasn't been that bad since. We were thinking we may need a new roof this summer however we were also thinking that maybe we just need more insulation in the attic. However after comparing our house with others in the neighborhood I think we have sufficient insulation. Our entire roof has about 8 inches of snow still, while most of the other houses do not have any snow left at all on their roof! So I really wonder if adding more insulation will fix our problem.

So we are thinking about just adding ice melt cables on this part of the roof. When looking around I noticed most people do not have them and that we don't know anyone with them. Does anyone have these and find that they help prevent ice dams or not? Do most people not get them because they cost a lot to run?

right now we roof rake any areas of the roof we can reach and do not have problems elsewhere. Our house has gutters and we try to keep them clean. The roof appears to be in ok shape, besides this problem. The previous owners did not know the age of the roof. They only lived in the house for four years.



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Better than cables is tin/copper looking squares. I see alot of them in our area. They are what look like decorative squares set at the bottom edge of the roof just above the gutters. The idea is that the metal will absorb the suns heat, snow will melt or slide off and not build up so no ice dams can happen.
I know the local historical society chose to put it on their roof cause it was less expensive, less of a fire hazzard than cables. You basically put it on when you do the roof and for get about it, so even if you are out of town when it snows the problem is dealt with. No worries.

    Bookmark   February 20, 2007 at 7:40PM
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We have terrible heat loss from our roof. Built in 65 with only 4" of insulation and no way to add more since it is a vaulted ceiling. We bought our house in the winter, so I knew it had massive ice dams. I had heat cables put on all of the roof edgings. We had an electrician fix a switch to the exterior plug so I can turn them on or off from inside.

Since you only have the damming at the valley area, can you get up there and put some more insulation under the area? Chances are, the isn't enough in that part, since ice dams in valleys of roofs are very common where I live.

We had really large snows this year and still had damming, but in regular years it has helped a great deal. Heat cables are very common here.


    Bookmark   February 21, 2007 at 1:26AM
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We had serious damage from ice dams on an older/faulty roof that required a tear-out of all drywall (ceiling and wall) and a full roof replacement.

We had the roof completely replaced one summer. The next summer we were able to have the interior torn out and replaced.

We decided we should get the thermo-cable placed to avoid that problem again - BUT now I am afraid to use it. We've been very lucky to have been spared the typical winter weather that incited us to place the heating cable so far.
Currently, I want to "flip the switch" as we do have an icy slick building...BUT there are leaves and twigs in the gutter that fell after the wire was placed that I was not able to clear before this snow. So, there is now a fire hazard if I activate the wire. Though, I would think, the melt from the snow/ice would avoid fire...I cannot be sure.
Damned ice dams!
Good luck

    Bookmark   February 21, 2007 at 2:29AM
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Puc13, I may be wrong, but I thought that the cables only got warm, not hot enough to start anything on fire.
Someone will have to verify this though.
I do LOVE those copper roof slides however noone seems to have them in the area, because we need gutters and when the snow slides off the metal it pulls down the gutters. Where I grew up everyone has them, however noone has gutters there. We actually redid our bathroom roof and added snow slides. Also, when we redo the roof we want a metal roof, so that is why I would like to fix the problem we have now without replacing our roof, because I want a bit longer to save for the new roof. I know we have a couple roof layers and it will be pricy to redo the roof, so I would rather not do it before it is needed.

Also We were thinking about placing the cables on the shingles. Is this better or worse than putting it in the gutter??

    Bookmark   February 21, 2007 at 8:33AM
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This is our first winter in our house so we have no history to go on. We have cables in a zig zag pattern on our eastern facing roof. They zig zag maybe a foot or 18 inches up and down the length of the roof and then the cable runs down into the gutters and is plugged in outside (with inside switch). We have a cedar shake roof. We have only used one time -- with that last snow/sleet/snow storm that the east coast got -- cables worked well -- only turned on for a short while.

    Bookmark   February 21, 2007 at 8:17PM
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I'd hope they don't get that hot, scryn, but the electrician who installed it noted to ensure there was no debris in the gutter or layered on the shingles as it could start a fire. Though, like I said, I suppose all the melting snow and ice would prevent ignition of any kind anyway... I'm just paranoid... and lucky to have had 2 40+ degree days to melt it naturally. I will need to look into it though.

Ours is installed much the way borngrace's is (about 18 inch zig-zags) but also extending in a straight line about 4 feet up a valley where we tend to get the ice damn on our western facing roof. Ours also runs the length of that gutter and partway into the downspout.

    Bookmark   February 22, 2007 at 1:34AM
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As I understand it, ice melt cable shouldn't be used when there are debris in contact with it. That's obvious. It also shouldn't directly contact the roof shingles.

And it should NEVER be turned on and left on continuously.

Barring cables, is the roof accessible enough that you could use a salt snake?

Essentially a salt snake is a sock or a leg from a pair of panty hose that is filled with calcium chloride (NEVER use rock salt, it will stain the hell out of your house) and laid on the roof either before a situation that would cause an ice dam, or after the dam forms.

I've used them a couple of times on my house in Virginia during really heavy snows.

The idea isn't to deice the entire roof, it's to cut a clear channel through the ice dam that will allow any water that has accumulated on the roof to drain.

One guy I knew in Pennsylvania had serious ice damming problems on his roof, and because of the construction type there wasn't much he could do about it. He rigged a system using a small pump and tubes that would when he turned it on, pump calcium chloride solution out of tubes he attached to the roof. It was a fairly low flow that he could increase or decrease as needed.

It worked amazingly well at keeping his roof free of ice dams because as the snow landed on the roof it never had a chance to accumulate where the calcium chloride was, and the calcium chloride also helped keep the spouting free.

    Bookmark   February 22, 2007 at 11:51AM
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The cables we were looking at show a picture of them attached to shingles, so I assume that is how they should be attached.
this is the product:

Thanks for the suggestion, we do use ice snakes. It is difficult to add the snakes on the roof though, we have done it though. Also we have read that this can damage the roof over time, because of the salt.

    Bookmark   February 22, 2007 at 1:34PM
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Ok, looks like a different design from the ones I've seen in the past. The ones I've seen before had little clips that kept them elevated above the shingles.

And yes, salt snakes can cause roof damage over time, ESPECIALLY to natural wood roofs.

    Bookmark   February 22, 2007 at 3:27PM
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regarding ice melting cables. DO NOT buy cables from the big box stores they do not work!! I have great insulation and ventilation, etc., but the ice dams were awful. I had installed a professional heating cable system and as long as I remembered to turn the goofy thing on before the freeze starts, no ice dam! Also there is an automatic plug available -try it, but you have to plug that in too! Also the cable can touch the roof-there is no way that it cannot touch the shingles. Good luck!

    Bookmark   February 22, 2007 at 5:22PM
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Wow you can say that again......cables from big box stores do not work..........what constitutes a professional heating cable system and where does one get one? Can you give me an approx cost? I live in the northeast and these ice damns are giving me a collosal butt ache......would steel roofs in problem areas eliminate the problem? What about flashing down these gullys? I have plenty of insulation, but an interior chimney close to the problem areas and a roof pitch issue.............please someone have some viable answers.....I'm sick of spending money on bandaids...thanks for your help!

    Bookmark   January 20, 2009 at 7:56PM
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Heating cables are the last "solution" that should be used in eliminating ice dams.

Assuming a vented roof, you should build or retrofit

* a well-insulated attic floor or cathedral ceiling to keep attic air and roof surface cold to prevent warm spots on the roof which can lead to snow melting.

* a well-sealed ceiling air barrier to prevent warm air from leaking into the attic.

* a ventilated attic or cathedral ceiling to keep the inside face of the sheathing cold in winter.

* a waterproof membrane under the roofing or at least the first three feet. This will not prevent damming, but will inhibit water from backing up under the shingles and into the roof structure and living space below.

Adapted from the: Manufactured Housing Research Alliance Attic Ventilation Design Strategies

    Bookmark   January 21, 2009 at 10:53AM
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"a waterproof membrane under the roofing or at least the first three feet. This will not prevent damming, but will inhibit water from backing up under the shingles and into the roof structure and living space below."

Yes, if you'r ehaving your roof redone, this is the way to go. Pretty standard now, although I think 4 feet is the standard. You could go all the way up in that area.

    Bookmark   January 21, 2009 at 1:57PM
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I don't have them but have been considering them - due to factors too complicated to go into here, it truly is a last resort-type situation.

I've been told they have a thermostat so only come on when temps are in a certain range when the thawing/refreezing is going on and the ice dams are likely to be forming. So you don't have to turn them on & off yourself.

    Bookmark   January 21, 2009 at 2:08PM
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Wow, someone really dug this up as I posted it two years ago. Anyways, we did install some ice melt cables and do turn them on when needed and they really do the trick.

We are getting a new metal roof this spring, with more insulation and ridge venting so hopefully that will help a lot. however, the roofing contractor said don't expect the metal roof to solve the problem of ice damming. You have to increase insulation and ventilation, which we are going to be doing.

However, for all those people asking about the cables, they did help us out a lot and I would recommend them for people that are not redoing their roofs right now and need to prevent the ice dams. We bought ours at a big box store and they work just fine.


    Bookmark   January 21, 2009 at 5:13PM
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Use Ice & Water Shield over the entire roof and set the gutters an inch below the projected plane of the roof so sliding ice can't rip it off.

    Bookmark   January 21, 2009 at 9:44PM
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hey all,

on the heating tapes...when should u put them on? when it is cold and snowy or when it is warmer and things are melting? To avoid the thought process is it advisable to get a thermostat? Also, on the uneven heating on the roof causing the melt....I've been obsessed with researching this and it seems that almost every house I see with an interior chimney (which I have as well) has snow melted around it and usually ice forming at the eaves. Part of the problem may be around here the codes are that you must have a 2 INCH structural clearance around the chimney. I called the fire department and that said not the plug that up with insulation.......geeze and it is no wonder that all that heat from the house rises to the attic and roof and causes a hot spot on the does anyone know anything about applying flashing around the chimney in the basement? or has anyone tried putting foam insulation on the interior of the roof above the chimney area in the attic? has anyone tried a ceiling fan in the attic to try and disperse the heat? please help brain is starting to go into severe overload on this more than annoying issue - thanks!

    Bookmark   January 23, 2009 at 8:35PM
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The air space around a chimney in the chimney chase can be safely sealed with sheet metal and high temperature sealant.

Here is a link that might be useful: Sealing an Old Home (scroll down)

    Bookmark   January 23, 2009 at 8:56PM
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We live in MA and had such a winter this year like we haven't had in years! So, we're not dealing with the ice dams next year (hopefully) like we did this year. The north-facing side of our house has historically been an ice dam-forming area. We've done lots of research on this, we've actually decided on a professional heating cable system. Having it installed this summer...(is it summer already???? It was 91 degrees today!) We can't install it ourselves (unfortunately) but the cost is still going to be way less than putting on a whole new roof, which we'll probably have to do in about five or six years anyway. And, when we do, we should still be able to reuse the parts from the system and integrate them into our new roof design. Check out this link to Bylin Heating Systems. Our contractor recommended them, plus we had a neighbor recommend it that had it installed on their home five years ago.

Here is a link that might be useful: Bylin Roof Ice Melt Systems

    Bookmark   April 28, 2009 at 7:36PM
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May I ask what the cost is for installing? Its got to be cheaper than the cost of a lawsuit from people getting impaled by the 6 foot daggers I have hanging off my house in the winter.

    Bookmark   April 29, 2009 at 11:00AM
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Our estimate for the materials and labor is around $2200. We opted for the smaller system, but if it works, it's CERTAINLY worth it to avoid a lawsuit!

    Bookmark   April 30, 2009 at 12:11PM
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I have had heat tape put in my gutters, down spouts and on the roof--my electric bill tripled. I don't know why is the best time to turn them off and on. I am on a fixed income and my electric is eating me alive!

    Bookmark   December 19, 2010 at 11:38AM
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It sounds as if you are leaving the heat coils on all the time.

This is a big no no, as the coils can burn out if left on continuously.

The best time to turn them on is just as it starts to snow. You're not going to get ice dams forming if there's no snow on the roof.

The best time turn turn them of is when your roof is substantially clear of built up snow.

    Bookmark   December 20, 2010 at 12:24PM
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Can anyone tell me what temperature range one can use to turn the cables on and off. Obviously the roof is warmer than the roof over the eaves which is why and when damming occurs. We now have a huge buildup of snow on the roof, and huge icicles hanging down from the eaves.


Here is a link that might be useful: The Garden Web

    Bookmark   January 23, 2011 at 6:34PM
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One of the message in this forum mentioned about Bylin Roof melt system. I am curious about how it is holding up this winter with all the storms we have been getting. If anyone has been using it also. I also live in MA. My back of the house faces north and I have a flat roof in one spot where my old house connects to the new addition we made 5 years ago. With all the storm we have been having I have water leaking from my ceiling through the light fixture in our study so there is a permanent bucket under it. I would like a permanent solution to our problem. We are planning to add more insulation to our old attic space. The roof for the old part of the house is only 2 years old. We did all the weather/water proofing. Wondering whether anyone can help?

    Bookmark   February 2, 2011 at 2:22PM
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Ss0510, you might try starting a new thread with your question.

    Bookmark   February 6, 2011 at 11:23PM
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Am grateful for all the comments on cost of ice-melt cable, especially the electrical cost. My neighbor had gutter *tape* put in her gutters over 15 years ago. This was cable embedded in some silver solar material (sort of like NASA heat blankets, I think). This wide tape lays in the bottom of her gutters. Her son said it makes cleaning debris out much easier than with plain cable.

I can't find any heat tape for sale now. Since it does seem that it would make cleaning easier (something I need to do a LOT), I wonder why they don't produce them anymore?

I did look up the Bylin system mentioned above, and there is also this:

These kinds of systems are, of course, a LOT more expensive to install. I don't know how they compare on cost of the electricity.

My split level was built in the early 70s. I am constantly cleaning out the gutters in warm weather and having ice bergs hanging off the roof in winter. It is a constant worry.

About 5 years ago I had more insulation put in both my attics (split level home) but I still have problems over the center of the lower level roof. This is over the center of the house, incl the kitchen so I guess that's why warmth is melting the snow. This past winter I also had a major ice build up on one of the upper level gutters. It was phenomenal!

Do I need to put even more insulation up or what? I am sure any analysis by any company selling ice dam prevention systems or insulation will insist their product is the solution. How do I know what to buy for my house?

Thanks for any feedback!

    Bookmark   August 1, 2011 at 8:53PM
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Has anyone used heat helmet sold by gutter helmet. It is a cable that goes into the gutter under the gutter helmet and then is wired into the electrical system in the house. It think it's called hard wired. It will probably cost me $1500 just for the front of my house. Will be worth it if it works, but how does one know?



    Bookmark   November 2, 2011 at 11:15PM
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My house is in Maryland and has a furnace in the attic. Needless to say, I get ice dams on the Northern side of the house. Laying more insulation on the floor isn't going to do any good. I'm not sure if insulation between the roof rafters will resolve the dams on the Northern slope. I do have vents in the eaves, a ridge vent at the peak of the roof and also a roof fan. Is heat tape the best way to prevent the ice dams? Any suggestions on how to compensate for the attic furnace and prevent ice dams? Thanks!

    Bookmark   November 27, 2011 at 9:29PM
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I guess the advertising for a plug-in solution beats sound building science any day.

Nevertheless, if you tighten up the leaky attic to upper floor interface, insulate to a higher standard, provide ventilation and protect the lower roof decking from ice backup you won't need cables. Furthermore, you will lower your fuel bills.

Here is a link that might be useful: Building Science: Ice Dams

    Bookmark   December 3, 2011 at 11:42PM
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I have heating cables on the roof. They are not on thermostat. It ia an old house. We had huge amount of snow the other day. Put cables on. Thay cut a path but i've had huge amounts of ice forming in gutter and some on roof. It's been sunny during day since snowfall but cold. Night have been -6 to -10 celcius, Should I have turned cables off at night. I did try to take some snow off the roof but i think i waited too long. what should I do and should i turn cables off on roof and gutters. Have been on since friday

    Bookmark   February 10, 2013 at 4:47PM
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Deep snow is an excellent insulator. Heating cables do not have the power to clear significant snow depth from a roof. In addition, as you have already discovered, what does melt refreezes when the temperature drops, gradually building up a thicker and thicker layer of ice at the roof eaves which makes it more difficult for snow to slide off.

Last Friday/Saturday's storm dropped an unprecedented amount of snow in many places in northeastern North America. Flat and shallow pitched roofs will be in real danger of collapse should rain add to the snow's already considerable weight. It needs to be raked off from the ground or shoveled off from above. The latter is dangerous - find a company that does it if you have the slightest doubt about your ability to accomplish the task. In any case, the heating cables will do more harm than good.

    Bookmark   February 11, 2013 at 5:54AM
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Thanks for your quick response. I have turned them off. The next few days are supposed to be 0 degrees celsius and -2 at night. It is worth putting them on again to melt ice in troughs either during the day or both?

    Bookmark   February 11, 2013 at 1:08PM
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I don't think so. Any water produced by melting some of the snow will refreeze. If it's possible to pull snow off the roof while standing on the ground by using a roof rake, do so. Sometimes roofing companies offer roof shoveling services. If you can get a good deal of the snow off, the heat of the sun this time of year will be a much more effective melter than the roof cables.

    Bookmark   February 12, 2013 at 5:22AM
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