how cold should my attic be? (1 Viewer)

[Jeremy Illingworth]

I live in Alberta, just north of Montana. In the winter we get lots of snow and lots of cold.

When I moved into the house I didn't realize that there was no attic ventilation in the house. We moved in in December and all was well but the next winter I had a small ice dam form over the bathroom and it leaked in, damaging the ceiling. The following summer I put in a pair of passive vents and some vented soffit. The next winter went by without incident but the following one had another ice dam and even more damage. Luckily I was too lazy to fix it the first time, so no work was wasted. This summer I put in a rotating vent and vented soffit on the entire house. I have convinced my self that this would be enough ventilation to prevent further damage.

I fixed the bathroom and now I'm getting paranoid that its going to leak again. Right now its -8 C outside and I've got a thermometer in the attic showing +2 C or about 35 F. Is this cool enough to keep from having more problems?

jeremy

 

[MikeH1]

I'm no insulater Jeremy but if its -8 outside and its 2C in the attic whats going to happen when it actually gets cold? Shouldn't an attic normally be warm with the warm air rising from your house and the insulation trapping the heat? Or is an attic supposed to be cold as not to melt the snow on the roof and create ice dams? (Gee I have more questions than you )
I think the attic ventilation (whirlybird?) is more for summer related problems. My father recently installed one and he said it helps keep the house more cool when hes trying to sleep during summer.
I know my post wasn't much help so maybe someone can clarify.

 

[Jeff Ulmer]

Your attic should ideally be the same temperature as the outside air, at least at the roof deck. The ice damming is caused by heat at the ridge melting the snow and having it freeze when it gets to the lower part of the roof, which prevents it from draining.
Try these articles for more info:
http://www.extension.umn.edu/info-u/...old/BK671.html
http://www.commerce.state.mn.us/page...er/IceDam1.htm

 

[BrianW]

It sounds like you're in pretty good shape if there's only ten degrees' difference. I don't think there's much more you can do to narrow that gap. The problem arises, however, when that gap stradles the freezing point, as it happens to do in your example. If it does this for a significant length of time, then ice dams are almost inevitable. But the narrower that gap, the less likely it is that weather conditions will keep that gap stradling the freezing point for any significant amount of time. Even so, it's bound to happen eventually, even with a 1-degree gap. It's just dumb luck, sometimes.

Again, I think you're in pretty good shape. Just watch the weather and keep an eye on your eaves when the temperature hovers at just below freezing.

 

[Bill Harada]

Is your attic insulated at all? If nothing else there needs to be sufficient insulation on the attic floor to keep the warmth from the house from heating up the attic space. The soffit vents combined with some form of ridge vent (is your rotating vent up high enough on the roofline to vent out any warm air?) should do a pretty good job of allowing cold airflow under the roof.

 

[Jeremy Illingworth]

Is your attic insulated at all?

The house was built it 1931 with an addition in 1951. The insulation is the same in both parts (kitty litter type) so I think it must have been added after the addition.

jeremy

 

[BrianW]

I knew that, but I didn't know if it was the ideal or the reality.

As the local Official Old Fart Homeowner/Handyman, I can tell you that it's strictly an ideal, difficult to achieve in reality without using NASA-inspired technology and/or allowing your whole house to freeze. You may be able to improve on that ten-degree differential, but everything you continue to do to lower this temeprature difference will yield progressively diminishing results. If you can, clearing or expanding the soffit vents over the problem area may be a good idea, however. Overall, I think you're actually in pretty good shape.
Did I mention that I think you're in pretty good shape?
(Is that an "Old Fart Homeowner" thing to say, or what? )

 

[Julian Reville]

if its -8 outside and its 2C in the attic whats going to happen when it actually gets cold?

And this isn't?

Jeez, I'm glad my ancestors decided to stop at the first river they came to. Brrrrrrrrr.

 

[Dustin B]

Nah, -8C is nice. Especially when the sun is shining, there is no wind and everything is covered in snow. I can walk a few blocks in that with nothing but a sweat shirt and jeans without it bothering me (provided there isn't a strong wind). Can take a long walk with a coat and toque.
Now when it gets down around -30C. That's when it's cold. Worst I've personally seen was -46 or -47 C with a wind chill near -60C. I walked 15 min to school in that too :p) Properly dressed it really wasn't that bad