Ice Damming: Roof venting or insulation problem?

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,

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.

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.

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

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.

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 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.

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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.

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.

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.

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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.

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.

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.

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.

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

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.

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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!!

nealtw said:

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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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.

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.

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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?

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.

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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

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?

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.

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

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.

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.

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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.