We had ice dams this winter, too, and we have 6' of membrane under our shingles! We think the water was going between the gutter & facia board, then running into the window & leaking. It all melted in 1 day so we dind't have to do anything other than DH getting on the ladder & pounding the ice with a hammer, but I did read online that you can fill pantyhose with calcium chloride and lay them on top of the ice in the gutters, and it will melt the ice. If it happens again we will do that. We have a Cape Cod style house and they are bad for ice dams. Could it be the style of your house? Do a google search on "ice dam removal" and you'll find a ton of ways to remove - but a lot of the cites mention the panty hose & calcium chloride so it must work.

Ya, that why I said "much" of the problem. I've always increased the size and slope of my eavestroughs to facilitate the ability of that near frozen water to get gone as well. Aggressive slope cures lots and you can trim it or paint it to minimize the street look. We have a few homes in Calgary and it can Chinook on you, be well above freezing and then drop, leading to immense ice issues if you don't get out in front of them. Between air sealing, insulation and good drip edges along with attention to the troughs and downspouts (don't make freezing water travel too far before you divert it down) we have substantially minimized our issues. And Brick is right, each home is a bit different, each geographical location is a bit different and here in Canada we don't have stuff like air handlers, hot water tanks or aircon in our attics, so you have to watch for those variables as well.

Coffeemama - I’m not sure you understand the reason for the ice dams. We had ice dams this year as well with water damage too. Even with freezing temperatures, if the insulation under your roof is not adequate, the heat is escaping through the roof and melting the snow. We had a hard time finding a contractor. I had a list of 10 from Angie’s List and went down the list. Had a couple of tentative promises to come and then no shows. We finally got an appointment for 5 days after the initial water started leaking. While we were waiting for them to come, I just couldn’t watch water keep coming into the house, so we called a local hardware store where we had received reliable advice in the past. They advised us to try to rake some of the snow off that we could reach without getting on the roof. And to buy pantyhose and calcium chloride and fill the stockings with that and place along the gutters on the ice. We called a family member to come and help, who advised that we get a ladder ‘stabilizer’ to add safety to putting the ladder against the house. They were able to get up to the gutters and using a roof rake pull off some of the snow they could reach and place the calcium filled stockings. This stopped the water from coming in and it stayed that way until the roofers came and got up on the roof and took all the snow off and knocked back some of the ice on the gutters. This was on the back of our cape that has a dormer on the back, so the roof is two stories high. In the front where the roofline is only one story high, my DH and son spent 5 hours pouring hot water on all the ice along the gutters in the front. It is a two person job, one person on the ladder, one ferrying the hot water pitchers back and forth. It did work though. Completely cleared the gutter in the front of ice. We could have done the same thing in the back, which is what we would have done if the calcium filled stockings had not done the trick. We've had to stay on top of it and keep getting the snow off the roof and take care of too much ice on the gutters. If I were you, I would call my home insurance policy holder and ask them to advise. They certainly don’t want you to continue to get water into your home and might have access to qualified contractors.

Ice damming is typically caused by the existence of an area at the lowed "edge" of the roof that does not have warm air beneath coupled with the upper portion of the roof having somewhat warm air beneath. In the classic case there is an attic with eaves extending out beyond the sides of the home. With the loss of any heat in the attic thru the roof directly above there is the potential for melting of the snow. There is no heat, or at least virtually no heat, beneath the eaves area therefore the snow above does not melt. The melted snow from the large area of the roof above the attic flows down the roof until it reaches the colder eaves area. That water now freezes above the eaves, forming an ice dam. The water now backs up against the ice dam and when enough water collects , the water works itself under the shingles and may seep down into the outer walls or attic. The water has the potential to evidence itself in seemingly odd places. It may flow down inside the exterior wall and not be seen or hear until it becomes visible around a window in the basement. It might run along your attic floor and pool in a low point and ultimately bring down a plaster ceiling. In the OP's case, seems an attic is not in play, but heat may be lost thru the insulted great room ceiling and melt snow above. The eaves are presumably not conditioned so the potential exists for an ice dam to form. With foam insulation also in your outside walls I'm not sure what could happen as far as water getting inside that foam envelope, but the potential for roof sheathing damage would exist. On a nice warm day you could remove a bit of your eaves vinyl and inspect for any history of ice damming. Some things that can be done to prevent ice damming might include: additional attic/ceiling insulation; a membrane installed beneath the shingles for at least ~4 feet before shingling; adding thermostatically controlled electric resistive heating wires in a saw tooth pattern extending that 4 feet to maintain a draining channel. I'm not a roofer, but I'm sure roof35 or others can tidy up my reply and possibly add other ideas.