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Canufixit 01-29-2009 09:20 PM

The moving Ice Dams after using a roof rake ??
The moving Ice Dams - after using a roof rake ??
Hi all,

I'll try to be brief - but as you can see I failed ...

- 18 year old house - never had any Ice dam before now.
- Attic floor Well insulated (12").
- Soffit vents are in - but I'll add more just in case in near future.
- Back side of roof (problem side) - north side - Ranch format slope.
- New England area - we have had a ton of snow this season.

So, last week we got dumped with about a foot of snow - I did roof rake the lower foot or two (as usual) - as this side of the house is 2 stories it's all the rake will reach without a ladder (and I can't get more around the roof edge from the ground).

Now for the issue - a week after the above mention storm and my roof raking - I still have 8" (easily) or more on the roof (which to me shows the insulation and vents are not completely that bad ...) - but with the current weather pattern - warmer days, colder nights - the little melting I do get just "Flowed" out of the roof rake line that I made, (the point where the roof rake cuts the snow - above is more snow - below is raked off) and this melting covered the foot or so I had raked previously with flow ice - causing - yup - the dreaded dam! (ceiling water spots at the eves)

So I get the ladder and remove another couple feet up the roof with the rake and manage to tenderly open some flow openings in the dam (and added Ice melt in the area, etc.) - I figured this should do the trick ... a few of days go by - and it's back again (Spots in the ceiling - now farther in from the eves / higher on the roof) - I STILL have 8 + inches of snow on the higher roof - and the dam has now moved up the the "new" roof rake line. Under this new roof rake snow line is - yup - the flow sheet ice. .... with the Ice dam in the snow line. I then repeated the roof raking and making flow channels - three times!! (It's pretty impossible to roof rake the whole side while standing on a ladder and trying to cop in to crusted snow with a roof rake all the way to the peak .... )

So What's going on ?? It sort of seems that the snow is acting like insulation for roof - not really melting that much (after all the roof is not 100% efficient in heat loss from the bottom side of the snow ...) - So, I thinking that some solar heating is adding some melting as well - but with the temperatrues swigs from around 32 or a little more in the days - then down to mid 20's or so at night - I'm just creating more dams - right at where I make the "roof rake line" .... So - if this happens again - I'll call a crew to shovel the whole back roof (Soutn side is a cape slope and not an issue) - but what am I doing wrong here ???

And thoughts ??? (and Thanks ALL !!!)


Ed the Roofer 01-29-2009 10:51 PM

Buy a second roof rake for about $ 20.00 to $ 30.00 and use the additional pole handle sections to create one very long handled roof rake.

I do it all the time.

It just doesn't make sense to me to only remove the bottom several feet of snow, when with just a little bit more time and effort, the entire roof can be cleaned off.


Canufixit 01-29-2009 11:46 PM

That's a LONG pole to handle on a shakey 2 story ladder for crusted snow. But I concur. My other question was - will using a roof rake to only partially rake a low slope roof cause new ice dams to form at the rake line? I've never heard of such a thing - and have not found reference to on the web. I do not understand how that can happen on a decent roof.thanks !canufixit*

OldNBroken 01-30-2009 12:13 AM

hint: what is the OUTSIDE air temperature under 3feet of snow versus 8 inches of snow? By removing that insulating layer you are just moving the freeze line farther up the roof. It actually doesn't hae much to do with your house temperature at that point.

I am assuming you've had winds with your cold because wind is generally the main factor in this. It doesn't take much more than a breeze for a drastic temp variation between the deep snow and the light snow. Options: shovel all of it evenly or shovel none of it. I would mention heat tape for the future but based on your detailed topic you are quite well aware of that. Plus that does you no good at this point.

Ed the Roofer 01-30-2009 01:05 AM


Originally Posted by Canufixit (Post 221757)
That's a LONG pole to handle on a shakey 2 story ladder for crusted snow. But I concur. My other question was - will using a roof rake to only partially rake a low slope roof cause new ice dams to form at the rake line? I've never heard of such a thing - and have not found reference to on the web. I do not understand how that can happen on a decent roof.thanks !canufixit*

Sorry, I didn't see where you said it was a 2 story home in your first post.

But, it still can be done, as long as you are safe on a ladder.

The brunt of the weight of those snow rakes are at the front blade portion. Once the reverse angle blade is on the roof, you just keep on pushing the pole farther and farther up the roof until it glides over the top of the snow and then pull down as much as you feel comfortable handling safely.

The thing I would be most concerned about, is pulling all that volume of snow down, so that a lot of it winds up going right on top of you.

If you have the balde portion on the roof and the slope is substantial enough where you can see the entire side from the ground, then you could still do it from the ground. I have, but I just push and pull a bit more delicately .


Canufixit 01-30-2009 08:09 AM

Thanks Ed !

And thank you OldNBroken !

- OldNBroken, This was kinda what I was trying to understand ... for the life of me, I just can't grasp why the Ice dam will re-occur in another location .... and why no where on the net could I find reference to this - if this is the case why snow rake your roof at all - unless you do the whole roof (as Ed says) - but there is no mention of this (and specifics of the causes and you mentioned). But I agree with your insight at this point..
- Short term - I'm waiting it out and we have a warming spell in the next few days and I hope the remaining higher snows is gone with this (it's well crusted snow and almost impossible to roof rake it off at this point anyway...) If I have further issues with the remaining snow I guess I'll have to call a contractor and have the remaing snow shoveled off (- if I can find one as a lot of houses in my area are calling them).

- Long Term - I'll have the whole roof re shingled replaced this year - and for this back side I beleive I'll need to get this single layer stripped (if not the whole roof) - add a membrane underneat the back side very high (6' - 8' up from the eves?)- if not the whole side membraned, get an insulation guy to check the attic for insulation / venting, etc. Hopefully then I'll have a roof that will not require snow rake usage - and I'll have the comfort of the warrenty and roofer behind me for years to come ...

If anyone else has insight or more info relating to OldNBroken's comments and the re-occuring Ice dams at the roof rake line - I'd love to hear them


dmc@RCR 01-30-2009 08:31 AM

You mentioned soffit vents.

Do you have ridge and /or gable vents to exhaust the warm attic air?

If not, add them to the long term fix.

Baffled 02-05-2009 05:17 PM

Having same problem
We seem to be having the same problem. I'll try to keep it short. 1 1/2 years ago had a new roof put on with moisture vapor barrier 3' up. First winter with new roof was OK. This past fall had blown insulation installed including the walls and attic. Have had 4 leaks into house this winter so far on the ceilings. This is occuring in the back of the house which doesn't get any sun really in the winter. This past leak 2 days ago it was 10 degrees out at 7:30 a.m. and was dripping in bedroom in the center of the room. The snow is cleared from about halfway down the roofline outside with the roof rake and there is no backup in the gutters but somehow the new leak sprung about where the snow line is on the roof where the roof rake would not reach. There is also frost running almost the whole length of the house in the attic at backside of house. Had the insulation contractors back out today thinking that something was blocking airflow after they insulated but all was good. They also installed soffit vents when they insulated as we did not have any in place. So currently for attic ventilation we have the ridge vent they put in with the new roof, new soffit venting and existing gable ends. Anyone have any clues as to what can be done to stop this leaking? We do have a bath exhaust fan but that is venting out through the eve not directly into the attic. We seem to be at a loss. The insulation guys say all good and the roofer says its not him.


dmc@RCR 02-05-2009 06:17 PM


You might want to go into the attic and check the situation for yourself.

Use this video of soffit venting and insulation for a reference guide;

Maybe take some pictures and post them here.

Baffled 02-05-2009 07:33 PM

We did check the attic yesterday. That's when we found the frost buildup etc. (It's not an easy feat getting into the attic) and called the insulation co. who determined the "proper vents" they installed are not blocked and there is air flow. It is definitely cold up there. Also noticed some of the roofing nails here and there were rusty already. There are pic's but kind of hard to see them since pretty dark up there. There is no floor in place to be able to really walk around.

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