There is a formula for venting that relates the size of the vents to the square footage of the attic. Soffit vents coupled with a ridge vent can provide good passive ventilation. When an ice dam has already formed, a professional may be able to stop or prevent water flow into the house by making channels through the ice dam to send the water in a different direction. If you are planning to replace your roof or have plans to build a new home, you may want to speak with your contractor about additional preventative measures. For example, a specifically designed rubber membrane can be installed under the shingles to help prevent water from entering your home.
Ice dams cause millions of dollars of damage to houses every year.
If you are unsure whether or not your home is safeguarded against ice dams, consult an insulation or roofing specialist.