The cold winter season is the time when many homeowners see icicles hanging from their eaves and/or water coming in the house due to ice damming on the roof.
Snow on the roof will eventually melt, but if the heat from the house causes the snow closer to the roof to turn into water, then that water can either go down slowly to the gutter or travel under the shingles. There is no heat at the gutter, so snow will remain there, creating a barrier. The water that is moving down will hit that cold snow barrier and then freeze again. This creates a dam (ice damming), which will hold the remaining water on the roof.
There are three main causes of ice damming:
- Poor insulation from a house ceiling. An attic with inadequate or deteriorated insulation can cause ice damming.
- Lack of ventilation. A house with proper ventilation allows the necessary cold air to mix and cool the hot air from the house, which slows the snow melting down.
- Leaking gaps between the living space and the attic. These spaces allow extra heat to “escape” into the attic, which warms the space and melts even more snow.
Shingle roofs are designed to shed water; they cannot handle having it freestanding. That is why a good quality Ice/Water barrier is needed at the eaves. This can only be installed by removing the first 36″ or so of your roof and installing it. This is why we recommend always installing ice/water shield at all eaves and valleys when we install roofs.
The most important thing we can do to help homeowners with ice dam problems is to first clean the snow off the roof (following strict safety rules) and then create exits for the trapped water.
In the long term, you should:
- Seal the living space.
- Install adequate attic insulation.
- Make sure that the attic is properly ventilated.
Preventing ice dams and icicles may not be possible at all times, but these are measures that can be taken to help stop water from entering the house.