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Old 02-09-2019, 12:39 PM
Dana Scully Dana Scully is offline
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icicles

Are they a sign that your home is poorly insulated? I have one area that has some serious icicles--anywhere from 12" to 24". Mixed in among them are smaller ones so I'm a little concerned. I had my roof "supposedly" insulated about 18 month ago and about a year later I needed to have it "topped off" because I couldn't discern any change and my energy bills went down very little.

So what do you all think? Do I need more insulation or...? TIA for your answers.
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Old 02-09-2019, 12:42 PM
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Not if they're on the outside.

Last edited by bobot; 02-09-2019 at 12:42 PM.
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Old 02-09-2019, 12:51 PM
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Reported for forum change.
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Old 02-09-2019, 12:53 PM
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Duckster, you're right--I posted in the wrong place. I meant to post it on the General Messages forum. Sorry!
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Old 02-09-2019, 12:54 PM
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If you have a bubble around your house providing climate control, that bubble may need more insulation.
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Old 02-09-2019, 12:54 PM
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You're lucky it didn't cut your eye! Those icicles have been known to kill people.
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Old 02-09-2019, 01:02 PM
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Duckster, you're right--I posted in the wrong place. I meant to post it on the General Messages forum. Sorry!
No, don't put it there! Snarky answers as the first reply are frowned upon there!
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Old 02-09-2019, 01:22 PM
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Duckster, you're right--I posted in the wrong place. I meant to post it on the General Messages forum. Sorry!
I can fix that.

Moving thread from ATMB to GQ.
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Old 02-09-2019, 01:41 PM
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You might still have an insulation problem. Hard to say without taking a close look at it.

If your attic is warm and your roof isn't well insulated, snow on the roof can melt, then re-freeze when it gets to the eaves (since there's no heat under the eaves), forming ice dams and icicles.

While the icicles aren't much of a problem (except that they'll put your eye out, kid!), the ice dams can prevent the melted snow from dripping off of the roof, so some of the water may leak inside your roof and into the home's interior.

The house I grew up in had heat tape along the eaves. When it snowed, we would turn the heat tape on, and it would melt any ice dams that tried to form there.

As far as ice dam formation is concerned, it's better to insulate the floor of the attic so that the heat stays in the lower parts of the house. If you let the attic get cold, then less snow will melt to form ice dams and icicles in the first place. Of course, this isn't always practical, as many homes have the attic converted into a living space that you wouldn't want to let get cold.
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Old 02-09-2019, 01:50 PM
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I learned this year that installing gutter covers (expanded wire mesh type) results in icicles. Snow now builds up right to the outer edge of the gutters.

Now the icicles drip onto walkway & patio, creating an ice problem.
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Old 02-09-2019, 01:56 PM
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Quote:
Originally Posted by Dana Scully View Post
Are they a sign that your home is poorly insulated? I have one area that has some serious icicles--anywhere from 12" to 24". Mixed in among them are smaller ones so I'm a little concerned. I had my roof "supposedly" insulated about 18 month ago and about a year later I needed to have it "topped off" because I couldn't discern any change and my energy bills went down very little.

So what do you all think? Do I need more insulation or...? TIA for your answers.
I think the poor man's test for that is whether or not your roof has snow on it a day or so after the snowfall. The snow melts more quickly from houses with poor insulation and less quickly from houses with good insulation (less heat is escaping through the roof), so a snowy roof is what you want.

Icicles form when dripping water freezes. One way that can happen is, as e_c_g said, when poor insulation lets the heat from your house melt the snow on your roof. But normal melting from sunlight and outside temperature can also cause icicles.

If you have really big ones, then that means that lots of water is flowing to that spot. Maybe you have a little dip in your roof there, or maybe two sections join there and form a kind of funnel.

And, of course, fireplace chimneys and vents for the central heat and the hot water heater can cause the roof to be hotter in those specific areas, so ice and snow will melt faster there.
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Old 02-09-2019, 03:14 PM
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Agree with Greyson Carlisle.

One question for the OP - is the spot where the icicles are forming on a south-facing roof? If so, it might just be from the cycle of sun during the day, freezing at nights. But if it's a north-facing roof, and the temperature's been well below freezing during the day, more likely that the icicles have been forming because of escaping heat from the house.
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Old 02-09-2019, 09:37 PM
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Icicles can also be problematic in that the weight can damage your gutters.

And you can also get some idea of the cause by comparing your house to your neighbors'.
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Old 02-09-2019, 09:55 PM
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Originally Posted by GreysonCarlisle View Post
I think the poor man's test for that is whether or not your roof has snow on it a day or so after the snowfall. The snow melts more quickly from houses with poor insulation and less quickly from houses with good insulation (less heat is escaping through the roof), so a snowy roof is what you want.
Of course roof material & direction / angle to the sun can play a big part it in. The back of my roof always melts faster than the front but that's due to solar heating.
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Old 02-10-2019, 04:35 AM
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In some places, the cops look out for snow-less roofs and send the sniffer dogs round to check for attic conservatories.
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Old 02-10-2019, 10:03 AM
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In some places, the cops look out for snow-less roofs and send the sniffer dogs round to check for attic conservatories.
How do sniffer dogs get to the attic? Are they training them to use ladders now or are they strapped to drones?
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Old 02-10-2019, 11:31 AM
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How do sniffer dogs get to the attic? Are they training them to use ladders now or are they strapped to drones?
Now you're being silly... They lower them from the helicopter in a harness of course.

Last edited by bob++; 02-10-2019 at 11:32 AM.
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Old 02-10-2019, 11:36 AM
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... But normal melting from sunlight and outside temperature can also cause icicles. ...
Not likely. If the sun can melt the ice, then the temperature must be near freezing (at least 28f (-3C) or so). That's not cold enough to re-freeze the water in the minute or so that it takes the water to reach the edge of the overhang.

There is a 99% chance that the cause of icicles is heat loss from your house to the roof. In other words, poor insulation in that spot.
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Old 02-10-2019, 03:43 PM
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Not likely. If the sun can melt the ice, then the temperature must be near freezing (at least 28f (-3C) or so). That's not cold enough to re-freeze the water in the minute or so that it takes the water to reach the edge of the overhang.

There is a 99% chance that the cause of icicles is heat loss from your house to the roof. In other words, poor insulation in that spot.
Water moves very slowly over (or under or through) snow, causing a drip, drip, drip throughout the day. At night, the droplets on the eaves freeze because the eaves are already colder than the roof because there's cold air from all directions at the eaves. More drips follow, forming an icicle. Repeat with more melting the next day and more re-freezing the next night.

Not to say that all houses don't have some degree of heat loss through the roof, but even in well-insulated houses, you can spend all day listening that that infernal dripping, then wake up the next morning to an impressive display of icicles.

If there's a 99% claim to be made for icicle formation, I'd apply it to gutter issues rather than with roof insulation.
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Old 02-10-2019, 03:46 PM
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Not likely. If the sun can melt the ice, then the temperature must be near freezing (at least 28f (-3C) or so). That's not cold enough to re-freeze the water in the minute or so that it takes the water to reach the edge of the overhang.

There is a 99% chance that the cause of icicles is heat loss from your house to the roof. In other words, poor insulation in that spot.
So the icicles on my unheated sheds are caused by some invisible heat generation device that I know nothing about? The roof over the attic is heated differently than the part over the eaves. My raingutters back up onto the roof every winter with ice. The insulation in my attic is on the floor. Nothing is against the roof.
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Old 02-10-2019, 04:01 PM
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What we like in cold climates, is a cold roof. Insulation not in the roof joists, but in the ceiling above the room. Keep that 'attic' cold. Vent it. If the attic is warm, it's gonna melt snow and create water for icicles. We don't bother with gutters or storm doors. Snow will rip your gutters right off. And a storm door that opens outward (as they do) can (and will) trap you in the house.

Snow dams/fences on the roof and heat tape are a whole nother issue.
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Old 02-10-2019, 04:08 PM
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Not likely. If the sun can melt the ice, then the temperature must be near freezing (at least 28f (-3C) or so). That's not cold enough to re-freeze the water in the minute or so that it takes the water to reach the edge of the overhang.

There is a 99% chance that the cause of icicles is heat loss from your house to the roof. In other words, poor insulation in that spot.
Yet another precinct heard from:

The patio roof we had when I was a kid produced the best icicles. Nothing remotely heated about the area under it.

Note that the sun would beam down on the top, not so much the edges.
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Old 02-10-2019, 05:09 PM
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So the icicles on my unheated sheds are caused by some invisible heat generation device that I know nothing about? ...
Ya got me stumped. My father has oceanfront property which he does not use from November to March. The house was built 60+ years ago and not well insulated. Dad turns the heat off and drains the pipes. I check the property once a month or so during the winter. I never recall icicles in the 40+ years I've been doing this. So I called my son who has an unheated, detached garage that he has owned for five years. Neither he nor his wife recall ever viewing an icicle on said garage. Both properties are in Massachusetts.
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Old 02-10-2019, 05:10 PM
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We had a bad year back in 2012-2013 where due to the cycle of snow, sun and freezing, everyone in our neighborhood had massive ice dams and icicles

When we re-shingled our roof a couple of years later, we had two of the big whirlie-vents installed and we've not a recurrence of the issue. The wind turns the vents, which suck the air out of the attic and keep it nice and cold. Haven't had the problem since.
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Old 02-10-2019, 11:21 PM
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We had a bad year back in 2012-2013 where due to the cycle of snow, sun and freezing, everyone in our neighborhood had massive ice dams and icicles

When we re-shingled our roof a couple of years later, we had two of the big whirlie-vents installed and we've not a recurrence of the issue. The wind turns the vents, which suck the air out of the attic and keep it nice and cold. Haven't had the problem since.
Ice shield is a good idea in winter climates. It's installed under the shingles and extends 3-5 feet up the roof from the eaves. Helps prevent ice damming.
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Old 02-11-2019, 08:18 AM
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Yes, we had that installed as well with the re-shingling.
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Old 02-11-2019, 09:44 AM
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I asked a policeman how they determine if the icicle is short enough to be evidence of a warm attic: do they compare it to a reference, and he said "policemen don't have test icicles."
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Old 02-11-2019, 08:31 PM
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Ya got me stumped. My father has oceanfront property which he does not use from November to March. The house was built 60+ years ago and not well insulated. Dad turns the heat off and drains the pipes. I check the property once a month or so during the winter. I never recall icicles in the 40+ years I've been doing this. So I called my son who has an unheated, detached garage that he has owned for five years. Neither he nor his wife recall ever viewing an icicle on said garage. Both properties are in Massachusetts.
Upper midwest. It takes the correct snow, temperature, sun combination but I've had 3-4" diameter icicles about 4-6' hanging from my abandoned dairy barn. Not always but usually several times during the winter. Most often when it starts to get near melting. The roof heats but the eaves and gutters are wind chilled below freezing. Water eventually pools and slowly drips over the sides, freezing along the way. My shed has an 8' overhang with a much lower slope than code allows and it generates pencil sized icicles quite often.
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