Ice dams can cause damage to your roof, and they can also harbour potentially dangerous icicles. One of the causes of ice dams is heat loss from your home -- the middle of your roof heats up, causing snow on the roof to melt and travel toward the eaves. Then, the comparative coldness of the eaves causes the melted snow to freeze and create an ice dam.
There are numerous things you can do to your roof to eliminate ice dams, but you also have to address heat loss from your house. Here are some insulation tips to keep in mind:
1. Insulate the floor of your attic to prevent heat migration.
To insulate the space between your top floor and your attic, you simply need to roll out ceiling insulation batts along the floor of your attic between the joists, and then, staple them in place. Also, if your attic has any spaces over internal wall cavities, roll some of the ceiling insulation batts over those spaces as well.
2. Secure insulation in corners.
Unfortunately, wind may get into the corners of your attic, and that can cause the insulation to fly up and leave the floor bare, allowing heat to transfer from your living area to the attic. To prevent that, use special care to ensure the insulation is well secured in the corners of your attic. For example, glue it in place or weight it down.
3. Allow ventilation into the attic.
If there are vents in your attic near the eaves or anywhere else, do not cover them with insulation. The vents allow cool air into the attic, and this helps chase trapped warm air out of the attic, preventing it from migrating to the point of the roof. Attic ventilation can be critical for helping to prevent ice dams.
4. Insulate heating ducts and light fixtures.
If you have heating ducts running through your attic, these may shed heat as well. To prevent that, cover them with insulation designed for ductwork. If you have light fixtures that are accessible in your attic, they can also allow heat to seep out of the living area. Do not lay insulation directly on the fixtures -- instead, invest in a cover and place the insulation over that.
5. Cover the opening to the attic.
When you've finally addressed everything else, don't forget about the potential heat loss through the attic entrance. If you have a wooden door or cover that leads into your attic, just glue a bit of loose fill or batting insulation to it. If you have a retractable ladder or larger entrances to the attic, consider investing in an insulated attic "tent" that sits in your attic on top of your door and has a zipper to allow entry as needed.