Icicles

On my walk with Kara yesterday afternoon, I noticed the icicles depending from the gutters of the houses in my neighborhood, some of them massive and eight or even twelve feet long. One of my neighbors had hired a team of roofers to use a steamer to remove the ice dam from their gutters. I had used a broom to remove icicles in areas I could reach to reduce the load and improve safety for those walking below.

As we walked along I mused over the differences in icicle formation. I’m not really sure why some houses have many more and larger icicles than others. I suspect it’s multi-factorial with reasons including:

• Houses with large expanses of roof with southern exposures tend to have more and larger icicles.
• Some roofing materials are more conducive to icicle formation than others. Based on my observation from least conducive to most: tile, slate, light-colored asphalt shingles, dark-colored asphalt shingles.
• Attic insulation. My impression is that more effective attic insulation is less conducive to the formation of ice dams and icicles.
• The temperature maintained inside the house. I’m not entirely sure about this one but I think that it may have some effect.

I’d be interested in hearing from someone with more knowledge than I on the subject.