Handling Snow and Ice Buildup on Your Roof

Now that we’re more than a few snow storms into the winter season, you may have noticed the amount of snow and ice buildup on your roof. An increased roof load, known as a “live load”, consisting of foreign material like snow and ice, can cause damage to your roof. This damage may not be apparent at first, but becomes more identifiable later on when the weather begins to warm up. Today we’re going to discuss the potential damage snow and ice can do to your roof, and how to fix it.

Roof Load

The weight of live roof loads can vary depending on the type of snowfall and the temperature outside. The likelihood of damage to your roof increases as the weight of the snow increases. The wetter the snow, the heavier it becomes.

  1. Light fluffy snow – 10 lbs./sq ft
  2. Heavy wet snow – 20 lbs./sq ft
  3. Snow/Ice Mix After Sunny Days – 40 lbs./sq ft

Typically, a modern roof is built to handle up to 50 lbs./sq ft (although LaValley-built trusses are made to handle more). When there is a lot of snowfall, it is easy for the 50 lb./sq ft limit to be surpassed, especially during New Hampshire and Vermont winters. In fact, 2 feet of snow can weigh as much as 80 lbs./sq ft. At this weight, a live load on an average sized ranch house roof (25’ by 48’ or 1,248 sq ft) would equal 99,840 lbs. of snow on your roof!

The solution to relieve the stress of weight on your roof is straight forward: use a shovel or roof rake to remove the snow as soon as soon as it falls. “As soon as it falls” is the key phrase here. We don’t want to let the snow have time to settle and form ice underneath. Otherwise, this causes another problem: ice dams.

Ice Dam

An ice dam is a large reservoir of ice that forms along the lower edge of your roof. These reservoirs grow up towards the peak of the roof. As it grows upward, the ice works its way underneath your roof shingles where it then melts, allowing water to leak into your home.

Here’s how to eliminate ice dams:

  1. The melting snow on your roof is the “food” source that is feeding the ice dams. You’ll need to shovel the snow at least 4 feet up the roof (but preferably the whole roof). No “food” means no additional ice is formed.
  2. Spread calcium chloride to melt the rest of the ice. Additionally, chip canals in the ice to allow the water to run off the roof more efficiently. However, this must be done carefully to avoid damaging the shingles.
  3. A more permanent solution to prevent ice dams is to first prevent heat from escaping your home in order to slow down the melting process. This can be done by making sure your attic is properly insulated.

NOTE: Never climb up on your roof unless you are qualified and take appropriate safety precautions.

Snow on your roof and icicles hanging from your eaves may seem like an ordinary part of the winter months in New England. However, snow and ice can be doing a lot more damage to your home than you may realize. Follow the tips discussed above and don’t hesitate to call your local LaValley/Middleton Building Supply for further assistance.

Listen to LaValley’s own Bob Jackman explain roof loads, ice dams and more by clicking here.

Additional Resource: This Old House. (2016). How to Treat and Prevent Ice Dams | Ask This Old HouseYouTube. YouTube. Retrieved January 10, 2022, from the video linked here.

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