我在这里向你讲述关于冰坝的故事，因为我们很多人都花时间处理它。当屋顶甲板底部高于冰点而外部温度低于冰点，并且屋顶上有雪时，冰坝就会发生。理解这一点很重要:当外面很冷的时候，你需要一个温暖的屋顶平台，你需要雪。如果没有雪，冰筑坝不成问题。我们在北极没有太多的冰坝问题，因为北极没有太多的雪。你可能会想，“等等，北极到处都是雪!”是的，但它已经在那里很久很久了。纽约州锡拉丘兹的降雪量比阿拉斯加州巴罗还要多。乘以10，这是一个很大的数字。如果有人把你的工资乘以10，你会注意到的。 Anyway, you need snow. Let’s assume we have snow. How much snow? Four or five inches of snow on the roof has got my attention. That’s prime ice damming conditions. To get that much snow on the roof, you typically need more than 30 pounds per foot of snow load on the ground in the wintertime. Most people know they live in an ice dam location when they notice their neighbors have ice dams. That’s a pretty good indication: You should worry about ice dams when there are ice dams. A buildup of hydrostatic pressure What happens when you start getting an ice dam? The snow melts. In the liquid phase, the water is wicked upward into the snow. The water is actually pulled away from the roof deck. The ice layer that occurs on the roof is several millimeters above the shingles. The liquid water, before it freezes, has the ability to run…