roof ice/snow

[MossRoad]

I don't have any experience with roof de-icing kits, but if you read the reviews they seam favorable.

Easy Heat Electric 160 Foot Roof De-Icing Cable

A co-worker just installed those a few weeks ago, before our bit 3' snow event. He said they work flawlessly and gave them a big thumbs up. :thumbsup:

Personally, I think they are a temporary fix and should only be used if you cannot get to the area in the attic/soffit and repair it properly. A good example of that is in cathedral ceilings, where you would have to tear out the inside finished ceiling to get in there.

 

[MossRoad]

Attic temp doesn't have to be kept at or below ambient temps.

The roof deck sheathing is another insulation so as long as the minor amount heat is ventilated from underneath the roof deck melting will be eliminated.

Like I said it works and I can prove it.

I'm with you on this one. There are tons of new houses around here where the snow never melts on the roofs and there are never icicles on the edges. It is because there is no build up of warm air in the attics. That is achieved through good insulation and proper ventilation.

 

[Gizmo2]

I have a neighbor that had repeated trouble with this same problem....after membrane under shingles and adding ventilation/insulation the thing that did the trick for getting rid of the heat (winter and summer) was one od these....

Roof Turbine Vents

He mounted it on the back side of house on roof (ugly to see from street) and the thing draws air out year round from his attic....he loves it and the ice buildup vanished....no electricity needed and quiet......

Yep, I did the same thing years ago. Put four units on the house and this solved 85% of the ice problem. Bought a roll of the 4" plastic corrugated drain pipe cut it into 2 ft lengths and then cut the lengths in half length wise and used them for venting between the rafters with the cut side up and two between each rafter.

 

[dave1949]

I think your over thinking this, the best prevention is just remove the fresh snow from the edge of the roof before it has a chance to freeze. Very easy to do on a ranch house, just have to go back 2-3 feet.

You will always have some loss of heat and since you mentioned south side that means it has something to do with sun shine, both the damming and the melting above.

JB.

Ditto that advice. South facing roofs over a cathedral ceiling may be one of the worst. I had such a roof, I thought the builder did a decent job of venting, but the fact is, cathedral ceilings heat the underside of your roof sheathing considerably compared to well vented attic where the air cools before it contacts the underside of the roof.

I resigned myself to cleaning off the 2' along the eaves after each heavy snow and that ended the ice buildup. It was a brown fiberglass shingled roof, 6/12 pitch, and the south side would melt off bare after a couple sunny days while the north side would melt hardly at all.

Your chimney and reflected heat rising from the glass doors are probably contributing factors, but not the root causes.
Dave.

 

[PILOON]

The cupola type of vent has been proven to be better than the turbine.
Turbine principal, while good, has a major flaw as in cold weather they generally freeze up and since they depend on bearings they tend to have a life as well.

As to cold air rising, sorry thats not the principle.
No matter how well insulated an attic will always be warmer than outside air and warm air rises.
If that warm air dwells it then warms the roof deck enough to melt some snow that causes your problems.
The principal is that a steady air flow, as minor as it is, will replace the warmer air with fresh cool autside or ambient air.

Block or prevent that action and the problems show up as ice dams.

 

[wdchyd]

Insulation and ventilation works and I can prove it. Just come on over any time and I will show you some new houses I built that dont have a lick of ice on them and then I will show show you any number of older house that do have ice dams on them.

:thumbsup:......I'm of the same mind Duffster.......

I've lived in the same house since 1967......when my parents owned the home there always was a problem with ice dams with water leaking in the house.....I can't remember how many times I've shoveled this roof as a kid off prior to 1983. In 1983 I added 9 or 10 inches of insulation to the attic ( which was only 3.5 inches) and side eve vents......

To this day, I've never had any problems since 1983.....not once....ice doesn't build up and I've never shoveled again......

Added only insulation and vents......Problem Solved..:thumbsup:

 

[JB4310]

Good interesting information here, I am a little skeptical though that venting alone is gonna solve the problem. I get the concept but have never seen that type of dedicated ventilation between every roof rafter, from soffit to ridge. I've seen that molded Styrofoam insulation that leaves the air gap but have never seen a house with it installed.

Probably because I do no new construction and am mostly working on older homes, but even on the newer homes I'm in I don't see that type of ventilation. It would be impossible to install continuous venting at the eaves of many older homes with little or no overhang/soffit and the rubber membrane would be the only simple effective solution.

I was clearing snow on a house today that had a wicked ice dam with ponding water behind it but there were no leaks inside or out, the guy said he had a new roof installed 2 years ago with the rubber. All I did was remove 2 feet of snow from the roof and left the ice.
Did another where he had a leak and I had to chop through 8 inches of ice to free the water, this roof was at the end of it's 2nd layer of shingles life, 40 plus years, so no membrane.

I'm sure good ventilation could be a key component to preventing ice dams/leaks on new construction or existing homes were possible to retrofit, but for the majority of the housing stock I come across the Ice and Water barrier is probably the best bang for the buck.

I guess it's true, you can't teach an old dog new tricks.

 

[wdchyd]

I've never had to do this, but a co-worker takes an old small soup can and mounts it on the end of an extendable pole.....partially fills it with "ice-melt" then reaches up and deposits it every couple feet just near the edge of the roof..

He claims it opens up a trough for the excess water to drain off......similar to chopping troughs with an axe but no trauma to the roof singles......

 

[Duffster]

I've never had to do this, but a co-worker takes an old small soup can and mounts it on the end of an extendable pole.....partially fills it with "ice-melt" then reaches up and deposits it every couple feet just near the edge of the roof..

He claims it opens up a trough for the excess water to drain off......similar to chopping troughs with an axe but no trauma to the roof singles......

I fill the gutters of a church we service with water softener pellets to keep the gutter and roof free of ice. They had water damage nearly every year until I started doing this. I can't recommend this if the gutters drain onto grass but here they drain onto the parking lot.

 

[MikeInMaine]

Sounds like a lot of pretty good advice. Take your pick:

1. Improve the insulation and venting below the roof.

2. Install Ice & Water Shield, or other waterproof membrane under the shingles

3. Install electric heat tape across the eaves.

4. Continue to rake the bottom portion of your roof.

Choosing which path to take means considering cost, ease of installation, and which method will give you the highest chance of success, and therefore the best peace of mind.

My pick would be the heat tape because it's easy to install and I know that it will work. Of course, I don't follow my own advice -- I rake my roof. Good luck.

 

[JB4310]

Sounds like a lot of pretty good advice. Take your pick:

1. Improve the insulation and venting below the roof.

2. Install Ice & Water Shield, or other waterproof membrane under the shingles

3. Install electric heat tape across the eaves.

4. Continue to rake the bottom portion of your roof.

Choosing which path to take means considering cost, ease of installation, and which method will give you the highest chance of success, and therefore the best peace of mind.

My pick would be the heat tape because it's easy to install and I know that it will work. Of course, I don't follow my own advice -- I rake my roof. Good luck.

I think 1 and 2 from your list would be all anyone would need. I see electric ice melt systems ocasionaly and almost always in some state of disrepair.

With the proper insulation, ventilation and Ice and Water membrane, raking wouldn't be needed for most houses.

My house today has ice build up with 2 foot iscicles hanging from the gutter, I'm not worried about leaks because my roof is unwalkable steep and I have the ice and water under it.
I am a little worried about getting shish-ka-bobbed by a falling icicle though

My house is 75 years old, 2 storey colonial with a 2 inch overhang, so there is no way to install venting at the eaves. there is a ridge vent but that is covered with snow now.
This house has just enough insulation where I wish it was better but am not gonna do an invassive operation to install more.

Last night it was 10 degrees outside and my attic (large walk up) was 39. I was surprized by how "warm" it was, it's usualy much colder and closer to outside temp. My wife pointed out it was the snow acting as insulation, guess she was right.

JB.

 

[zukota]

It's not always venting.

This roof has no insulation, its an addition on the north side of my house. The roof you are looking at is a bit that faces south. The snow melts runs down and hits the shadow of the existing house and freezes.

Membrane isn't the answer because it is cut where the roof meets. It's currently not flashed correctly - but I'm not confident that correctly installed flashing will be 100% waterproof when the water is pushing up the roof.

I've been considering a little crook to keep the melt above the shadow line.

 

[Duffster]

Membrane isn't the answer because it is cut where the roof meets.

Not if done correctly.

 

[zukota]

Not if done correctly.

Not the material I'm using.. There is no way it's going to lay down along that show rafter and up the valley. It's called ice and water shield locally. If your thinking of something else, I'm interested to learn what it is. Or are you saying to lay it in like a flashing - I didn't think of that.

I'm not to proud to rip that section off roof off and re do it. Gotta pull some it up to fix the old fascia anyway.

 

[JB4310]

It's called ice and water shield locally. Or are you saying to lay it in like a flashing - I didn't think of that.

Not to answer for Duffster but that's pretty much standard around here. (ice and water in valleys) as underlayment, has to be covered with roofing.

You could even run it up a wall in a real problem area behind siding or flashing.

JB.

 

[Sumpter]

Replace the roof with metal. You won't have that problem anymore.

 

[wdchyd]

I have a couple of neighbors that clear away the snow for 3-4' off the roof edge....(the snow is 1 to 1 1/2' thick).....

My question, wouldn't the ice build up at the edge of the snow (3-4') up on the roof and do more damage leaking into the house above the ice/water shield..??.....it seems to me that this would be worse than just leaving it to melt natually.....or shovel the WHOLE roof......

 

[Duffster]

Not the material I'm using.. There is no way it's going to lay down along that show rafter and up the valley. It's called ice and water shield locally. If your thinking of something else, I'm interested to learn what it is. Or are you saying to lay it in like a flashing - I didn't think of that.

I'm not to proud to rip that section off roof off and re do it. Gotta pull some it up to fix the old fascia anyway.

I use "Winter Guard" but it is basically the same thing . If done correctly which is kind of tedious it can seal that valley and wall perfectly.

I won't be able to explain how to do it in less than a thousand words so I could draw you a picture if you like?

 

[Duffster]

Replace the roof with metal. You won't have that problem anymore.

Sure.