Northern state residents with roofing knowledge....

[ChrisL]

I'll give a narrative of the problem and then ask my question to anyone who may offer their advice. Much appreciation in advance:

Here in Minnesota we had a brutal winter last year. Speculation is we're in for another. The snow was well past my waist on our roof this last winter and caused some ice damming before I could remove the snow. The ice dams caused some water damage inside. The ice dams were a result of inadequate venting and warm air passage from a room with a 10' high ceiling in which we have a wood stove that heats that room (an addition). The main home runs West/East. The addition runs North/South forming a "T". Where the roof line of the main home and the roof line of the addition meet, the two valleys are where the ice damming occurred.

I'm not the original owner so I've inherited these problems. Here are the reasons why the ice damming occurred:

1) The space below the peak of the roof of the addition, the "attic" area was completely uninsulated. I mentioned the 10' walls in that addition; there is a shared wall separating that addition and the main home. On the other side of that shared wall above the doorway is that uninsulated attic area.
2) There were two small (2'x2') access doors near the ceiling of the addition on the inside wall of that finished room leading to that uninsulated area. Using a ladder, you could peek your head inside each of those doors. The original shingles of the main part of the home serve as the "floor" in that uninsulated space since the addition's roof was just tied into or roofed over/above that portion of the main part of the house. The previous owners had just cut some rigid pink styrofoam as an air barrier behind those access doors which did not create an airtight seal in any way.
3) The wood stove used to heat the addition (approx 26' x 26') burns day and most of the night. The air temp at the ceiling level is about 105 degrees. That hot air was leaking into that uninsulated air space under the roof of that part of the addition through those two little access doors and creating the ice dams.

SOLUTIONS:

1) Contractor added four roof vents three on one side of the peak and one on the other in that roof area of the addition directly above what was that uninsulated space. There was a ridge vent running the length of that addition, but not effective.
2) He insulated that air space with cellulose insulation.
3) He also sprayed the entire backside of that shared wall with about 3"-4" of closed cell polyurethane foam and permanently sealed those two access doors, foaming the cavity for each then sheet rocking. This was done to stop any warm ceiling air from making its way into that airspace and to serve as a vapor barrier to prevent any condensation from the hot side of the wall to the cold side of that wall inside that roof airspace.

Here's my question:

I'm glad the four roof vents are there. When I have snow cover on the roof though, the venting capabilities of those vents will be rendered virtually useless, won't they? Is there some product made that you can put over roof vents to shield them from the snow? I thought about tipping metal garbage cans upside down and cutting a few holes in the bottoms (which would then be the tops) but that idea seems lame. It would allow the top of the can to be above the snow cover maintaining the venting capabilities of the vents.

Any thoughts?

Not burning the wood stove is not an option...

There are two ceiling fans in the addition and I plan on running those clockwise during the winter to redistribute that warm ceiling air the best I can.

Thanks!

ChrisL