This time of year, snow capped roofs are a common sight in the northern parts of the United States. But, not all snow covered roofs look alike and not all snow covered roofs are equal.
Whether the snow on your roof is a perfect blanket, or it has splotches of melting spots, that says something about your home and its efficiency.
A roof that is evenly snow covered means that home’s insulation is doing its job. Think about it: during the winter months we put a lot of effort into heating our homes. However, heat naturally rises. So, if your home has lots of leaky spots and not enough attic insulation, that warm air is going straight to the attic and out to the roof, melting snow.
If you start to notice big spaces on your roof that aren’t snow covered, you have a problem. Those are areas where the insulation is not working properly. Not only are you losing energy and money, these patches of melting snow can lead to serious problems such as ice dams.
An ice dam forms when snow begins melting from the upper parts of the roof, but re-freezes once it hits the overhang at the bottom of the roof. Ice builds up, creating a dam. Water from melting snow gets blocked behind it and leaks into your home. This Old House points out that shingles are meant for water to run down, not up. Which means that when water from melted snow gets backed up behind an ice dam, that water can get underneath shingles and into your home.
The best way to prevent this from happening is by making sure that your attic is properly insulated.
An even covering of snow on the roof means that the insulation inside is working well. It also means that your home is receiving an extra layer of insulation against cold outside temperatures. Paul Fisette, wood technologist, explains,”…on average snow has an R-value of 1 per inch — about the same as wood. Twelve inches of snow have roughly the same insulating value as a 2×4 wall filled with fiberglass insulation.”
After the next snowfall, make sure to examine your roof for any splotchy, melty areas. These can be signs of poor insulation, and it is best to fix those before major problems such as ice dams occur.