aluminum gutters

[blinko]

I have a valley on my metal roof on our house with aluminum gutters at the roof edge. In the winter I end up with a ice dam at that spot. Any sugestions on preventing this. Is there a electric deicer, I believe salt would be bad on the gutters.
Any ideas would be great

Thanks.
 

[Ted in NE-OH]

Ice dams are caused by poor insulation or poor ventilation causing snow to melt and then when the water gets to the colder part of the roof it freezes again. Worth checking out.
 

[Steven-Id]

They make a deicing cable. It is used to melt the edges of the roof and also put in the gutter and down spouts to keep the water flowing.


Steven
 

[MarkB_MI]

I have deicing cables on my house and they work very well if installed properly. They will prevent formation of ice dams and will also keep your gutters from freezing. You can get them at the usual places: HD, Lowes and many hardware stores.

Ted is correct that a properly designed and insulated roof shouldn't get ice dams, but many houses have such poorly designed roofs that no amount of insulation or ventilation will prevent dams from forming, my house being one of them.

If you get a dam, don't use salt on it. It's not only bad for your gutters; the salt can get to the nails in your roofing. A trick I'm told works well (I haven't tried it) is to fill a ladies nylon hose with calcium chloride and place it across the dam. This will cut a channel through the dam and allow water to drain out. The dam itself isn't the problem, it's the water that backs up behind it.
 

[Stephen Newell]

Ted in NE-OH is correct. Close to the edge of the roof there is no heat from the attic keeping the roof warm. When water runs down the roof it builds up there and makes the damn. The ice damn can also cause water to back flow into your attic damaging your house. The only thing you can do is try to make the soffit more air tight insulate so the roof can build some warmth there. It may be necessary to close some of the vents in the attic in winter to retain the heat the house is generating. Another option is you could install heat tape along the roofs edge just above the eaves to help warm the roofs surface. I'm in Texas so ice isn't so much of an issue here. Any house I've ever worked on had absolutely no insulation in the area of the soffit. If this isn't insulated it would allow more cold air there to freeze the roof.
 

[Dave Sherburne NY]

Like Ted said you need to insulate your ceilings better, check for places where heat is escaping into the attic and eliminate them and make sure your attic is well vented so the roof stays cold and doesn't melt the snow which when it runs down the roof refreezes on the eaves and builds ice dams.
 

[MarkB_MI]

Stephen, I'm afraid you have it backwards. To prevent ice dams, you need a cold attic. If the roof temperature stays the same temperature from peak to eave, ice dams won't form. Ice dams form when the roof over the attic is above freezing, and the roof over the soffit is below freezing. This usually happens at night.

Adding insulation to the soffit will do nothing to prevent dams, because there's no heat source to warm the roof. But adding insulation and ventilation to the attic will prevent snow from melting when the outside temperature is below freezing.

I never heard of ice dams while living in the Texas panhandle. And down in SE Michigan we have it easy compared to folks in the Upper Peninsula.
 

[Pops1532]

MarkB is correct.
Another cause of ice dams can be the weather itself. Here in IL we can have wild temperature swings. Especially in late winter. Warm temps during the day can melt the snow which then freezes at night causing an ice dam. Heat tape usually works. I've seen squirrels chew it though so check it periodically.
 

[ss55]

You see ice dams on houses without rain gutters too. To reduce ice dams add better vents to your attic so the roof stays the same temperature as the outside air temperature. Gable vents help a lot when the roof has deep snow cover. Turbine vents work too but they are noisy and don't look right on a house.

Some slope on the gutters helps the gutters drain out better, but home builders always install them level for looks rather than function.

To reduce the ice in gutters I've drilled small 1/4 inch diameter drain holes in the bottom of a rain gutters under a valley so the corner drains better in winter. I put a wood screw to plug the drain in warm weather.
 

[showcrop]

Mark B is correct. You want a cold roof surface to minimize snow melt. Check for good soffit venting, and also in the attic for Proper Vents to be sure that there is air flow space above the insulation between the soffit vents and the open attic.
 

[Stephen Newell]

Actually the point I was trying to make is to force the heat all the way out to the soffit area heating the roof there so the water will drain off the roof not making a damn in the first place.
 

[Pops1532]

[barnE]

On my first car 54 ford, buddy who did siding made replacement quarter panel out of siding aluminum. Barely lasted a year. Salt ate it out. Dave