I have a weird fascination with icicles. During the winter, I like to travel around certain neighborhoods and scope out the size of icicles hanging off of houses. While they can appear to be “beautiful,” I recently learned how truly ugly they can be. Not only are icicles a sign of inadequate attic insulation, it could be a start of a serious problem — ice dams.
What is an ice dam? According to the University of Minnesota, “an ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow from draining off the roof.” That water will back up behind the ridge and can leak into the home, damaging walls, ceilings and insulation.
What causes an ice dam? In that same article, from the University of Minnesota, is a very detailed diagram as to how an ice dam can form. Here’s a simplified diagram I created that illustrates what happens.