Icicles and ice dams - prevention

[Sibley]

Most of my town is having problems with icicles, ice dams, and snow on the roof. I am no exception. My gutters are full of ice from top to bottom. The north side of the house is much worse and there is an ice dam as well as very impressive icicles. Luckily my roof is quite steep so snow/ice has been sliding off rather than building up. The roof is new and there is ice & water shield, so I'm not highly concerned about damage right now, but I don't want this to happen repeatedly.

My assumption is that better insulating the attic would be helpful. Is there anything else I should consider? Attic is unfinished, access is easy.

[Papa bear]

I’m assuming you have a “cold roof” where your insulation sits on your floor joists or rafter ties above the ceiling.  If not and your insulation is under the roof sheeting then this doesn’t matter as much.

I’d start with looking at insulation/air sealing to prevent warm air from getting to your attic and then look to make sure you have adequate venting.  You need to keep cold air moving through the attic, such as with soffit vents and ridge vents, or hat vents, or gable vents. Make sure that if you have soffit vents, they aren’t blocked, either with insulation inside or dirt/crap/leaves/bug nests outside.

I’m no expert on venting, as there is a lot that goes into the air flow.  I’m a fan of soffit vents with ridge vents myself, and typically when you add a ridge vent, you remove the hat vents and cover or block the gable vents.


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[Sibley]

Yes, cold roof.

I will make sure that the soffit vents are in good order, but I'm pretty sure they were looked at when the roof was replaced last summer. There is a ridge vent, no hat vents, as well as some vents in the gables that are probably ineffective. When I was inspecting the attic this summer, there was noticeable air flow. And I'd already planned to do air sealing, that one I know.

[Papa bear]

With your soffit vents, make sure that blown in insulation isn’t blocking them, or you’ll need to install baffles.  And also, quick back of napkin, but make sure you have the same amount of venting from your soffit that equals your ridge. 


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[BudgetSlasher]

There have been some good points already. Assuming your house is the issue. Usually what is happening, is somewhere on your roof the temperature is above freezing and where you have ice the temperature is below freezing. Usually the below freezing is the eaves as they are not over the heated portion of your house.

If this is the case, as has already been mentioned.

1) Make sure there is good airflow through the attic (eave to ridge/end vent) to remove any heat that works its way in there.
2) Try to eliminate any air leaks into the attic, the bring large amounts of heat and cost you money.
3) Added insulation can help.

In New England there have been various attempts to address the symptoms and not the cause. A couple include heat tape on the edges of the roof and metal roofing for the last foot or 2 to allow easy shedding of ice.

Not that I recommend it, but I've known people to throw salt on ice dams as a last ditch effort to clear them; technically it works, but I cannot imagine repeated salt exposure is good for a roof. 

If your house is not the primary driver insulation and air sealing will only do so much:

For example this year we have icicles in places we have not for the past 7 years, including the roof of the unconditioned garage. Recently our weather has included days where the weather include rain as part of a wintery mix. Rain when the temperature is below freezing will turn to ice, it is just a matter of how quickly and how far it runs down your roof and/or drips. (Inches of wintery mix in a day also make one's driveway super fun to clear)

[lthenderson]

Excellent advice up above. I've never had any problems until this year and the only difference is I replaced my gutters recently with the metal mesh leaf guard shield built in. From what I have seen, the mesh is so fine that heavy snow just piles up on it, compresses, and forms a crust which melting ice now trickles over instead of through the mesh because inside the gutters it is empty. I'm not having ice/water back up under the shingles yet but there are a lot of icicles hanging off my gutters right now. I think this summer I'm going to install heated cables underneath the mesh that I can plug in as needed.

A good way to judge how affective your attic insulation and ventilation is to just go to your street and look at all the roofs around you. On my street, comparing similar pitched roofs, mine is the last one to remain covered in snow. To me this verifies all the insulation and increased ventilation I have done over the years. If your roof is the first one without any snow on it, then you probably need to spend some time insulating, sealing and adding more ventilation as suggested above.

[BudgetSlasher]

Excellent advice up above. I've never had any problems until this year and the only difference is I replaced my gutters recently with the metal mesh leaf guard shield built in. From what I have seen, the mesh is so fine that heavy snow just piles up on it, compresses, and forms a crust which melting ice now trickles over instead of through the mesh because inside the gutters it is empty. I'm not having ice/water back up under the shingles yet but there are a lot of icicles hanging off my gutters right now. I think this summer I'm going to install heated cables underneath the mesh that I can plug in as needed.

A good way to judge how affective your attic insulation and ventilation is to just go to your street and look at all the roofs around you. On my street, comparing similar pitched roofs, mine is the last one to remain covered in snow. To me this verifies all the insulation and increased ventilation I have done over the years. If your roof is the first one without any snow on it, then you probably need to spend some time insulating, sealing and adding more ventilation as suggested above.

Good simple tip. I would also add if you can see the outlines of your roof framing while you are out at the road in the snow/snowmelt pattern more insulation, attic ventilation, and/or air sealing is probably warranted.

[Fishindude]

Sometimes there is no preventing it and you will get ice build up along the eaves, no matter how your structure is insulated, etc.
Get the right combination of snow, moisture, cold temps, etc. and the gutters and downspouts freeze solid.  When things start thawing out, the leaks occur.   This has been a bad year for it.

I was a builder my entire career and my recommendation is anytime you can build without need for gutters leave the darned things off.  Gutters are probably the single biggest source of roof leaks and problems, primarily because they don't get maintained, and also due to icing per this discussion.   I have a bunch of buildings, and none of them have gutters.

[Jon Bon]

Sometimes there is no preventing it and you will get ice build up along the eaves, no matter how your structure is insulated, etc.
Get the right combination of snow, moisture, cold temps, etc. and the gutters and downspouts freeze solid.  When things start thawing out, the leaks occur.   This has been a bad year for it.

I was a builder my entire career and my recommendation is anytime you can build without need for gutters leave the darned things off.  Gutters are probably the single biggest source of roof leaks and problems, primarily because they don't get maintained, and also due to icing per this discussion.   I have a bunch of buildings, and none of them have gutters.

Interesting comment. Some of this is location dependent I assume? I would never dream of leaving gutters off anything where I live due to inevitable foundation issues that would result. That being said some places with very sandy soil do not need gutters.

I guess with most things there are trade offs to all solutions. Currently I don't think I have any issues as of yet. Suppose to warm way up next week so hopefully that will be the end of the ice damns.

Also the way you feel about gutters is the way I feel about chimneys! I have way to many of them and they are always the weak spot.

[lthenderson]

Interesting comment. Some of this is location dependent I assume?

Very location dependent. In the land of clay and basements, gutters are mandatory but I've been other parts of the world where they have higher water tables and different and thus no basements and gutters are fewer and farer between. If I had my dream house, I would probably skip the basement altogether, extend the eaves as far as practical away from the house, have rock landscaping below and no gutters. They are a royal PITA as far as I am concerned. If it weren't for them, I wouldn't have been up on my roof at all in the last ten years of living at this house.

[Aegishjalmur]

Depending on how tall your house is and how steep you roof is you could do a couple things besides better insulation in the attic:

1. Get a roof rake. use his to pull the excess snow off the roof and away from the gutters. Start pullimg the snow off when
 the winter starts and then keep up on it. https://www.homedepot.com/p/True-Temper-17-ft-Telescoping-Roof-Rake-193055510/202943651

2. If your roof isn't easily and safetly accessible for using the roof rake, you might consider this. Roof and gutter cables like this: https://www.homedepot.com/p/Frost-King-200-ft-Roof-Cable-Kit-RC200/202262345

[Fishindude]

Interesting comment. Some of this is location dependent I assume?

Very location dependent. In the land of clay and basements, gutters are mandatory but I've been other parts of the world where they have higher water tables and different and thus no basements and gutters are fewer and farer between. If I had my dream house, I would probably skip the basement altogether, extend the eaves as far as practical away from the house, have rock landscaping below and no gutters. They are a royal PITA as far as I am concerned. If it weren't for them, I wouldn't have been up on my roof at all in the last ten years of living at this house.

It's really not location dependent at all, you just build with this in mind.
Where the water drips off your eaves, it needs to hit some type of hard surface so things don't erode, and that surface needs to be sloped away from the building and allow the surface water to get way rather than stand there.

We've got a lake house in northern MI, big snow and cold country.   Nobody puts gutters on their homes for the reasons mentioned.  If they do, they don't last long.

[Sibley]

Mass reply :)

House is 2 stories tall, roof is VERY steep. I overheard the roofers saying that it's extremely steep and to be cautious. I have ladders that can get up there, but due to the snow/ice and my general inability with heights, that's not happening. All this mess is going to have to melt on its own and then I'll deal with the results as needed.

This weather is unusual. We've had a mix of very cold, lots of snow, and decent amounts of sun, and that's resulted in ice build up on everyone's roofs. It's basically a perfect storm for ice dams. I'm getting icicles in places where I haven't before, and where I have had icicles in the past they're much larger than usual. My downspouts have also been solid ice for a few days.

I don't have snow on the roof currently. Part of this is the slope (I've seen/heard it slide off), but also I'm aware the insulation is inadequate.

My gutters are in good shape, or were. They're currently full and overflowing with ice. Hope they aren't damaged by this.

I'll plan to air seal, check/fix soffit vents as needed, and add insulation. That should help considerably.

The weather is supposed to break this weekend, so all the snow and ice will start to melt. It's going to be a mess.

[BlueMR2]

This weather is unusual. We've had a mix of very cold, lots of snow, and decent amounts of sun, and that's resulted in ice build up on everyone's roofs. It's basically a perfect storm for ice dams. I'm getting icicles in places where I haven't before, and where I have had icicles in the past they're much larger than usual. My downspouts have also been solid ice for a few days.

Yep, it's been a bad year for it (but we've had worse at this house before too).  Even my (unheated) shed with steep roof and no gutters has ice build up all along the bottom of the roof.  Too many days with just the right combination of temperature in the 20's, direct Sun on black roof, and snow layers thin enough to melt, but thick enough to generate a fair amount of water, trying to drain into white gutters.

We're just about to hit 30 degrees today and we're getting more Sun now (both due to season and finally clouds have gone), so I went out and cleared the snow layer off the top of the gutters portion so the Sun can get to it better (but left the fairly thick snow layer on the rest of the roof for now, I've tried clearing the whole roof before and since you can never get it fully clean it ends up making things worse as a thin layer will quickly melt, run down, and refreeze even faster).  Knocked off all the icicles and did the salt on the gutter / downspout outlets as best I could to try to help it out.  Can see where we already had some water down in between the wood siding and the vinyl siding.  A couple areas where it looks like some water came through the soffit as well.  So far, inside walls/ceilings are dry, but am expecting to get some water around one door in particular eventually.

Most of the houses around are in even worse condition.  I've had our (cold) attic insulation and venting checked and we're as good as can be.  I was tempted to leave gutters off when the siding was done a couple years ago, but our neighbors did that and with the rain we get in the Spring it's a foundation disaster.  Can't keep dirt there, keeps getting washed away.  Thinking our only real way to permanently solve the issue is a standing seam metal roof, but that has it's own set of downsides...  I may go that route anyways when it's time for a new roof.

[Cranky]

My metal roof is usually the first to be snow free in our neighborhood. However, because this time we had more ice than snow, the gutters were full of ice to begin with and the roof melt has just made it worse because there’s nowhere for it to go.

[norajean]

We had an ice dam and leak related to a skylight which melted ice and sent water to a lower roof which somehow leaked due to the damming. I lowered the temp in the room with the skylight and that helped a lot. I should review the seal around the edge of the roof where it leaked once weather improves.

[reeshau]

Not that I recommend it, but I've known people to throw salt on ice dams as a last ditch effort to clear them; technically it works, but I cannot imagine repeated salt exposure is good for a roof. 

I did this fairly regularly in Michigan.  It's not just salt, but rather hockey pucks of salt.  They melt their way to the gutter, and make a tunnel within it.   So contact with the roof is fairly minimal, particularly if you aren't careful to hit the same place each time.  Everyrhing still looks icy, but the melt has somewhere to go.  My brother in Minnesota makes his own by stuffing salt in nylons.

https://www.amazon.com/Roof-Melt-by-KMI-RM-65S/dp/B000QCDG5S?th=1

It's funny reading the 1-star Amazon reviews, which describe the product working exactly like this, but It's not what they want / expect.  Read the friggin' directions!!

[Sibley]

Thanks to a change in weather, things are melting. The south side of the house is pretty much clear, it was never as bad though. I looked at the north side and there is ice retreat happening, as well as it appears there's a gap between the ice and the roof. We'll see how that works out. But there is ice and water shield under the brand new roof, so cross your fingers.

I'm also expecting flooding later this week as snow and ice continue to melt. The ground is frozen and with all the piles, no where for the water to go. This has happened previously, my house will be fine. Maybe a bit of water in the dirt crawl space which will resolve itself.

[Fishindude]

Yea, it's melting off here too.  Keep hearing large slabs of ice slide off the barn roof.
Some of those hunks are big enough to kill you if you were standing at wrong place, wrong time.

[Sibley]

I noticed Fishindude! Had an ice sheet break and fall from the utility room roof this morning, certainly large enough to seriously injure anyone caught below it. It destroyed the dryer vent and the external outlet on the wall. It managed to trip both that circuit as well as the main breaker. Electrician is coming tomorrow morning to fix the outlet. I'll fix the dryer vent this weekend.

The ice dam on the house is melting. Not gone, but much shrunken. I'm seeing some water coming out the bottom at least. Hopefully another day or 2 will melt the rest. South side roof and gutters are completely clear.

[Steeze]

My dads house usually gets giant icicles and ice dam in the winter. This year he had an energy audit done and had insulation blown in the attic, sealing throughout the house and soffit vents added. No icicles at all!

I asked him about the ice dam and what to do, he said to throw heat tape on top and let it melt through to create channels. Eventually the ice slides and your heat tape goes with it. Rinse and repeat as needed. Next year install the heat tape properly to the shingles so you don’t have to keep setting it back in place.

[MasterStache]

Some great suggestions. Our house was the only house on our street without ice damns and icicles. Right after we moved in I added another R30 in attic insulation. I also replaced all the old rotted wood soffits with vinyl ventilated soffits along with cutting in and installing a long ridge vent. I did not block the ventilated soffits with insulation (very important). My neighbor actually came over and asked about the ice damns and how to prevent them.

[lthenderson]

Due to all the snow and freezing weather, I was very concerned about ice dams this year though I have never experienced any in the last 9 years we've lived here. I thought we made it through since I never found any leaks and the snow and ice is all safely removed from the roof. But this morning I walked by my tablesaw in the garage and saw the top of it was a rusted mess. Evidently there was an ice dam above and the water leaked down and through the can light directly over where I had parked it for the winter. So I spent an hour sanding off the rust and polishing everything with wax. I think I'm going to look into some heated cables for the future.

[Fishindude]

Due to all the snow and freezing weather, I was very concerned about ice dams this year though I have never experienced any in the last 9 years we've lived here. I thought we made it through since I never found any leaks and the snow and ice is all safely removed from the roof. But this morning I walked by my tablesaw in the garage and saw the top of it was a rusted mess. Evidently there was an ice dam above and the water leaked down and through the can light directly over where I had parked it for the winter. So I spent an hour sanding off the rust and polishing everything with wax. I think I'm going to look into some heated cables for the future.

I've noticed a lot of the homes in northern Michigan that have shingle roofs, have the lower overhang portion of the roofs covered in sheet aluminum or painted steel flat stock.  Assume this is to the ice dams easily slide off, as opposed to gripping to the shingles?   Looks like a pretty good idea to me.

We tried lots of different things with heat trace on big industrial buildings to combat these issues.   Can't say any were ever highly successful.

[lthenderson]

I have never seen a "two tone" roof like that with metal on the bottom and shingles on top. But I haven't been to Michigan in a long long time. I'll have to keep an eye out for that the next time I'm there. It does make sense. Kind of the best of both worlds.