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.

thanks,
renee

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.

Gloria

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

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

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.

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.

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.

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

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

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.

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.

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.

-renee

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 roof.......so 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 .....my brain is starting to go into severe overload on this more than annoying issue - thanks!