# Ice Damming: Roof venting or insulation problem?



## johnnie1600 (Mar 22, 2015)

Hello all, thanks in advanced for any opinions.

I need some advice regarding ice damming on my fiancee's lean-to style roof.  In the picture attached, I have placed red arrows indicating the areas where most of the ice damming occurs.  I have been told by some roofers that it is because there is no venting and that the roof would need this done in order to abate the ice damming problem.  However, I have also had someone tell me that it is more likely due to poor insulation.  This is a lean-to style roof, so the ceiling in the front room (where the arrows are) slopes up all the way to the second floor (where there is a mezzanine).  There is no intermediate floor acting as an air gap (like an attic), so essentially my thinking is that there is basically only a 2x6 or 2x8 rafter between the great room and outside?  I am pretty handy over all, but don't know much about roofing.  My buddy swears it is poor insulation, and roofers she called to chip off the ice dam swear its the lack of vents.  I could see it possibly being either, but who knows?  We need to be informed before potentially spending a bunch of dough we don't have on an expensive fix.  Can anyone help me with this debate?  I really appreciate the help and advice.

God bless,


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## nealtw (Mar 22, 2015)

Welcome the site.
Both are likely correct. Even with lots of insulation heat will escape from the top of the wall and venting will moive that heat up and out. Is that a vaulted ceiling on the inside. In order to have venting you need are to enter near the gutter and vents near the top, but you do need a path for the air to flow. So if the ceiling inside is vaulted you will have to figure how much room is left up there above the insulation.


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## johnnie1600 (Mar 23, 2015)

Thanks a lot for the feedback.  I am not sure if it falls under the classification of a vaulted ceiling?  I can say that the ceiling follows the pitch of the roof all the way up to the second floor, so the "main room"  has a ceiling that starts out about 9' and pitches up to about 20' or more? (that's a guess).  Not sure if that helps but I drew up and have attached a quick cross-section of the house.

Thanks again very much.


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## nealtw (Mar 23, 2015)

I call that vaulted. The soffet is the under the roof above the windows outside, How is that finished. Solid wood or???


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## johnnie1600 (Mar 23, 2015)

Sorry, I guess I was picturing the inside of a cathedral when you said vaulted!  Okay, I don't remember off hand, what the soffet is constructed out of.  I want to say it is tongue and groove, but I am not sure.  I will check later today and post back.  I do know that the crew of "roofers" she had out here to chip off the ice dam, claimed that the soffet vent covers were "just for show".  They were a tad shady, but then again, this would not surprise me given the way the house was built.  In one of the back bedrooms, the exterior wall was completely devoid of any insulation whatsoever.  Couldn't believe when the drywall was pulled off for examination, there was nothing but sheathing. Unreal. Worried ever since they cut other corners in this house.   Thanks again for your time.


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## Groaman (Mar 23, 2015)

I have had major ice damn problems this winter and so have many of my neighbors. Venting the roof of adding insulation won't guarantee that they won't form.

The best protection that I have found is the the heated wires you lay on the roof and in the gutter. Unfortunately, I didn't put them up this year because I didn't have to plug them in over the last two winters. I was lazy and paid for it this winter.


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## johnnie1600 (Mar 23, 2015)

Groaman said:


> I have had major ice damn problems this winter and so have many of my neighbors. Venting the roof of adding insulation won't guarantee that they won't form.
> 
> The best protection that I have found is the the heated wires you lay on the roof and in the gutter. Unfortunately, I didn't put them up this year because I didn't have to plug them in over the last two winters. I was lazy and paid for it this winter.



Yes, I have been thinking of going the same route.  Im not sure how much having vents installed after the fact will cost, but im sure it wont be pretty.  The idea of spending that kind of dough on something that might not fix the problem is kind of scary.  I have been reading up a little on thermal resistance of snow and its R value after it builds up, and even a house theoretically "sealed" could see damming due to materials being different temps, etc.  Not a great explanation I gave there but suffice it to say, I am a little skeptical of a "fix".  Do you know if those wires are removable "off season"? They are a bit on the unsightly side in other seasons.  I'll take the good with the bad tho. 

Thanks a lot.


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## DFBonnett (Mar 23, 2015)

The condo units across from my daughter's condo are north facing. The middle two units of four have ice dam problems. The wires stay up all year. They turn them on when needed.


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## johnnie1600 (Mar 23, 2015)

DFBonnett said:


> The condo units across from my daughter's condo are north facing. The middle two units of four have ice dam problems. The wires stay up all year. They turn them on when needed.



Yeah, I was thinking they probably are meant to be up all year.  I was hoping it could be something I could put up and take down like Christmas lights.  Thanks a lot.


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## slownsteady (Mar 23, 2015)

The easier thing to check is whether the soffit vents are real or not. Using a ladder, take a close look at the underside of your eaves. If they're solid (no perforations or slots), then you don't have proper venting. If they do, then you need to get up on the roof and see if you have a working ridge vent. Both have to be present and operating to provide proper venting.


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## nealtw (Mar 23, 2015)

Easy or hard is depending on how the roof was constructed. If it was built today it would have 2x10 rafters and it would be strapped with 2x4s. that gives lots of room for insulation and lots of venting around the sky lights and will work fine with soffet and a few box vent.
The problem with the heater cord over the wall is it dosn't do anything for the skylights which may be the problem for all the same reasons.


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## DFBonnett (Mar 23, 2015)

johnnie1600 said:


> Yeah, I was thinking they probably are meant to be up all year.  I was hoping it could be something I could put up and take down like Christmas lights.  Thanks a lot.



Possibly there are some you can. The people across from my daughter are the antithesis of a DIY type.


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## johnnie1600 (Mar 24, 2015)

Groaman said:


> I have had major ice damn problems this winter and so have many of my neighbors. Venting the roof of adding insulation won't guarantee that they won't form.
> 
> The best protection that I have found is the the heated wires you lay on the roof and in the gutter. Unfortunately, I didn't put them up this year because I didn't have to plug them in over the last two winters. I was lazy and paid for it this winter.



Groaman, so you put them up and take them down each year???  That is what I think I would like to do??  Please let me know!!


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## johnnie1600 (Mar 24, 2015)

nealtw said:


> I call that vaulted. The soffet is the under the roof above the windows outside, How is that finished. Solid wood or???



Hey nealtw...here is a pic.  I attached a pic of the soffet.  You cant really tell from the picture (and I dont know why I didn't check this before now) but if these arent functional vents then the builders went through quite an ordeal to make it appear as if the roof is vented.  I can see that there is a void behind the soffet that must lead somewhere. I think now the roof is possibly vented, its just that they arent doing their job keepuing the building mat. cold enough??

Would love your feedback.


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## johnnie1600 (Mar 24, 2015)

nealtw said:


> Easy or hard is depending on how the roof was constructed. If it was built today it would have 2x10 rafters and it would be strapped with 2x4s. that gives lots of room for insulation and lots of venting around the sky lights and will work fine with soffet and a few box vent.
> The problem with the heater cord over the wall is it dosn't do anything for the skylights which may be the problem for all the same reasons.



I appreciate that very much.  We are not getting any damming or ice build-up around the skylights at all fortunately.  The damming is only on the eves.  I posted a response with a pic to your earlier inquiry about the soffets.  After examining them, I think the roof is vented.  Perhaps it is as you say.  The construction might not have sufficient enough room for insulation and ventilation to do their job?  I read that even if vented and properly insulated, given the right conditions, you could still have damming problems which is why I am leaning toward the heated cable now.

Your thoughts?


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## johnnie1600 (Mar 24, 2015)

slownsteady said:


> The easier thing to check is whether the soffit vents are real or not. Using a ladder, take a close look at the underside of your eaves. If they're solid (no perforations or slots), then you don't have proper venting. If they do, then you need to get up on the roof and see if you have a working ridge vent. Both have to be present and operating to provide proper venting.




Thanks slow.  I took a pic of the soffets.  There are multiple vent covers that are obviously covering a hole which leads me to believe there must be vents in the roof.  I'm not sure what to look for in terms of the ridge vent.  I guess I can google it.

Thanks a bunch


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## nealtw (Mar 24, 2015)

Any way you can get up there and remove that screen and inspect. And can you look at the skylight from inside and estimate how thick the roof is?


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## nealtw (Mar 24, 2015)

johnnie1600 said:


> Hey nealtw...here is a pic.  I attached a pic of the soffet.  You cant really tell from the picture (and I dont know why I didn't check this before now) but if these arent functional vents then the builders went through quite an ordeal to make it appear as if the roof is vented.  I can see that there is a void behind the soffet that must lead somewhere. I think now the roof is possibly vented, its just that they arent doing their job keepuing the building mat. cold enough??
> 
> Would love your feedback.



The heat cable may be the best answer, but I would want to know what ever is going on first.


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## nealtw (Mar 24, 2015)

We see no vents on this side of the building, are there boxes or? on the other side near the top? The opposite room to this one , has it got a flat ceiling with an attic above it.


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## johnnie1600 (Mar 24, 2015)

nealtw said:


> We see no vents on this side of the building, are there boxes or? on the other side near the top? The opposite room to this one , has it got a flat ceiling with an attic above it.



That is a really good question about the boxes/no sign of vents.  The rooms opposing the roof we are talking about all have slanted ceilings I believe.  I would have to check to make sure.  Great idea about looking at the skylights to get an idea of the size rafters they went with!!!  Thanks.  It's looking like the cables might be the best bet.  If there are no real existing vents...it would probably cost a fortune to have them installed.  Another small fortune to do the insulation.  I might get quotes for both, but my guts are telling me the venting and insulation are just not adequate do to the framing members being too shallow?  Just a guess at this point. 

I will double check all of those suggestions you gave.  You've been very helpful, thanks a lot Neal.


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## nealtw (Mar 24, 2015)

My question is why just this area. It could be that everything was done with the right plan with some silly mistake. 
The ridge vent talked about earlier would be under the flashing at the top of the roof and would be about  1' thick mesh like product.


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## johnnie1600 (Mar 24, 2015)

nealtw said:


> My question is why just this area. It could be that everything was done with the right plan with some silly mistake.
> The ridge vent talked about earlier would be under the flashing at the top of the roof and would be about  1' thick mesh like product.



Good point about it being localized?  There are no dams at all anywhere else.  Perhaps you are right about a mistake, seeing as how they completely forgot to insulate one of the bedroom's outer walls.

Will check ridge vents and report back.   Thanks again Neal.


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## nealtw (Mar 24, 2015)

Your roofer suggested vents, what was he suggesting?.


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## johnnie1600 (Mar 24, 2015)

nealtw said:


> Your roofer suggested vents, what was he suggesting?.



Okay, to clarify:  Unbeknownst to me, one day my fiancee had some crew come out to remove the ice dams this winter.  I got there as they were finishing up and spoke with the crew leader.  I gotta be honest, I didn't get a warm and fuzzy from him at all, and was sure he was fishing for work.  He claimed the vent covers were just for show and that we needed roof vents.  I found that hard to believe and thought he was fishing for work for a roofer he was associated with.  As soon as I learned what they charged her, and confronted him on it, he b-lined for the truck.  My girl got taken.  I didn't trust a word he said.  

Anyway, maybe he wasn't full of it...but I haven't had a chance to investigate until now.  I considered having some roofers and insulation guys come out and give me their quotes.  I am sure they will both tell me it is their brand of expertise that will be the solution. 

Not trying to sound cynical, but it's been one of those years.  I am a fairly handy guy actually.  Just don't know anything about roofing....yet. 

Thanks again.


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## nealtw (Mar 24, 2015)

I think your best bet is to understand the system as best you can and in doing that you may find the problem, then at least you would know who to call if it is something you can't do your self.
He may have poked  at the vent and found no hole behind it. But even if there is a hole there, there are two other requirments that may not be there. Continuity from the vent along the soffet so air can travel up each bay between rafters, the other is an air gap between the insulation and the roof sheeting to give air a space to move up the inside of the roof. Both these are ralitively easy fixes from the soffet area if there is a space to be used above the insulation in the rest of the roof.


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## johnnie1600 (Mar 24, 2015)

nealtw said:


> I think your best bet is to understand the system as best you can and in doing that you may find the problem, then at least you would know who to call if it is something you can't do your self.
> He may have poked  at the vent and found no hole behind it. But even if there is a hole there, there are two other requirments that may not be there. Continuity from the vent along the soffet so air can travel up each bay between rafters, the other is an air gap between the insulation and the roof sheeting to give air a space to move up the inside of the roof. Both these are ralitively easy fixes from the soffet area if there is a space to be used above the insulation in the rest of the roof.



yeah that all makes a lot of sense.  I am gonna remove the cover and check that out.  I am gonna also get up on the roof and check the ridge vent out.

Ill post back with my findings.  Thanks again.


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## nealtw (Mar 24, 2015)

You will find this interesting.
http://www.finehomebuilding.com/how-to/qa/venting-a-shed-roof.aspx


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## Groaman (Mar 24, 2015)

The cables aren't meant to be left up there all year long. They should come down in the spring and go up in late fall.

They aren't hard to put up and are very inexpensive. Especially  compared to cutting in a roof vent or adding soffit vents that might not work anyway.


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## bud16415 (Mar 24, 2015)

Around here a lot of people have been going with metal roofs. Standing seam comes in a variety of styles. They are creating an air space by laying a new roof over sleepers and then the metal. I don&#8217;t know if it&#8217;s a good idea or not but I see a lot of conversions and they seem to shed snow well and eliminate ice damming. I&#8217;m not sure how they do the venting top and bottom.


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## nealtw (Mar 24, 2015)

bud16415 said:


> Around here a lot of people have been going with metal roofs. Standing seam comes in a variety of styles. They are creating an air space by laying a new roof over sleepers and then the metal. I dont know if its a good idea or not but I see a lot of conversions and they seem to shed snow well and eliminate ice damming. Im not sure how they do the venting top and bottom.



The tin roof roof on sleepers creates an ice house roof discribes in the article I posted.


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## bud16415 (Mar 25, 2015)

nealtw said:


> The tin roof roof on sleepers creates an ice house roof discribes in the article I posted.




 Thats exactly what they are doing (ice house roof). 

  On the OPs roof only thing different he would have to deal with is the sky lights.


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## johnnie1600 (Mar 25, 2015)

nealtw said:


> You will find this interesting.
> http://www.finehomebuilding.com/how-to/qa/venting-a-shed-roof.aspx



Wow, yeah that confirms why I found no ridge vent for that section of roof last night when I went up there, and confirms what you noticed in the photo a couple days ago.  Nice find Neal, thanks a lot.  Makes me think I might have been right about that "roofer with 20 years exp."  Who knows, maybe he had never encountered a shed style roof.  

Looks like cables might be the best solution after all.


You have been extremely helpful.  You have my gratitude.


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## nealtw (Mar 25, 2015)

That was the first time I have seen that too.


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## johnnie1600 (Mar 25, 2015)

nealtw said:


> That was the first time I have seen that too.



Guess I should stop raggin' on that roofer.  

Thanks again.


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