A friend has just returned from a trip round Canada and that other bit higher up that gets very cold and starts with an A. We are all fascinated with tales of Bison steaks and twentyseven foot tall Elks or was it Mice which get aggressive and you have to dial 55 to stop them nesting in your chalet porch and igloos with gas fired ducted central heating and flowers grown in hanging baskets because the dirt never thaws and Australians weren’t warned that sandals aren’t really suitable for exploring glaciers which creak and keep you awake nights unless you dial 55 and the cruise ship had lots of foreigners on it and you shouldn’t rub your eyes just after you have been finger printed on the border of that bit that starts with A and they all drive on the wrong side of the road because the bears have never really adjusted to going metric and break into your fridge if you use perfumed deodorant unless you dial 55 to get hotel passivated bears which lie at the foot of your bed so you can warm your toes.
One other thing she mentioned which raised my curiosity was that somewhere in her travels she noted that the walls of houses had an extra layer or skin to stop ice forming in the wall. As a builder in warmer climes where insulation is used to keep heat out I got to wondering where was this icing a problem, how severe it was and how was it dealt with.
If someone could give me not too detailed run down it would be greatly appreciated. And I could tell you about how we park our cars to prevent the tyres from melting.
Replies
Glaciers are best explored barefoot. The reason we drive on the other side of the road is the same reason water goes down the drain the opposite way. And the bit about gas powered central heating in our igloos is ridiculous. We burn Polar Bear dung.
I'm not sure what you mean by an extra layer of skin on our houses. Here in BC (Canada) we put Osb or plywood sheathing followed by tar paper or housewrap, then the siding. The house needs to be insulated properly so that Ice dams do not form on the roof. what happens is that heat escaping from the house melts snow, which turns to water, which then freezez again. this causes ice dams wich block proper runoff from the roof, and allows water to creep into places it should not go. But extra skin? Unless, of course, you reffering to the seal skin parkas we wrap our houses when the weather turns particularly bad, like -75.
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People are entitled to their own opinions; People are not entitled to their own truth.
Jacob
psssttt.......... vapour barrier
I usually put vapour barrier on the inside of my walls... :)-------------------------------
People are entitled to their own opinions; People are not entitled to their own truth.Jacob
JJ - I think the OP is talking about our national igloo. Threatened by global warming it is, according to subject matter expert Rick Mercer.
Might be talking about a layer of foam board insulation on the exterior, between sheathing and siding, to break thermal bridging and condensation in wall cavities. Ray Moore has posted about a variant of it on this board, the PERSIST system developed at U of Alberta I think...
Thanks guys for your comments, a year or two back I read in Fine Woodworking of a workshop in your neck of the woods having one foot thick insulation. I cant remember the location but it was (by my standards) bl**dy cold. Now given that temps inside a building are high with corresponding humidity content and outside it is well and truly freezing at some point within the wall there is a risk of condensation forming and freezing. This in turn reduces the insulating property of the wall and the problem gets worse.
Obviously this doesn't happen so either my theory is wrong or your building techniques prevent this happenning. So for the benefit of a Australian builder who cant possibly imagine coping with such cold conditions outside of building freezer rooms, just how thick are your walls and where is the vapour barrier?
Ray
We need to get Dave Thomas to look at this thread. He knows the science involved, and actually lives in Alaska.
-- J.S.
Science is pretty ez on this. When warm air travels towards cold, it will actually condensate when it reaches what's called the dew point. The dew point can actually be calculated based on the average internal and external temperatures (and their variance) and the amount and type of insulation.
The purpose of the vapor barrier (more correctly called a vapor retarder) is to prevent the water vapor from entering the insulation cavity and condensing. THe vapor retarder should be placed on the warm side of the wall.
Here's a web site that explains the calculations pretty thoroughly.
http://www.professionalroofing.net/article.aspx?A_ID=589
Edited 10/12/2005 4:28 pm ET by Brutag
I live in Australia and they put the vapour barrier in the same place as we do!