It’s winter (not technically, but it’s December). Typically from December through February, depending on where you live of course, there’s not a lot of rain coming down. Snow, sleet, and ice take over during the cold months, so why would an otherwise functional roof start to leak in the middle of winter?
The answer is Ice damming. If you already know what this is and how it works, you may move on to checking your ebay items or to your online Christmas shopping, but if you don’t know what an ice dam is, please read on. I want to just briefly explain what it is.
An ice dam (or ice jam) occurs when water builds up behind a blockage of ice.
When snow on a roof melts, moves down the slope, and re-freezes further down the roof, it could potentially create an obstruction preventing additional water from passing. This water may then be forced uphill and underneath shingles where it could find passage into the structure. Roofing is only designed to keep out water that’s travelling downward with gravity.
There’s nothing we can do about these crazy weather cycles. What we can do, as I wrote about earlier this week, is make sure an excessively warm attic isn’t what is melting that snow. If it is cold outside, and warm in the attic, the snow can melt and the water may then re-freeze at the edge of the roof where there is no attic under the roof. Now you have a huge ice barrier all the way around the edge of the roof, playing bully to the poor water that just wants to get to the gutter.
Nobody likes a bully. Make sure your attic is properly insulated.