by Frankenmuth Insurance on Tuesday, February 1, 2011 at 11:01am
Ice dams can cause extensive water damage to a home or structure. Recent record-breaking winters throughout the country have caused damage to tens of thousands of homes as a result of ice damming.
Definition/How Ice Dams Form
A cycle of melting and refreezing occurs when snow accumulates on a roof. Two key factors that interact to cause a problem include the outside temperature and the temperature inside the attic of an affected home.
The warmer the temperature is inside the attic, the more the snow will melt at the roof surface. Typically, the melted snow should flow off the edge of the roof. When the air temperature is very low, the melted snow refreezes at the edge of the roof, where the interior roof surface is not being warmed by the attic. The refreezing forms an “ice dam,” which is a collection of ice that blocks the path of other melting snow.
As this dam continues to form to a certain height, the melting snow behind it will leak back under the roof shingles and eventually even into the home’s interior. On those roofs with a low slope, a small amount of “ice damming” will result in water backup and damage in short order.
Primary Prevention Measures
- Insulation – Installing additional insulation on the attic floor will reduce the temperature in the attic. Keep in mind once you reach the area’s optimal R-Value (a measure of the insulating value of a material), a further increase in the amount of insulation will not show an appreciable decrease in heat loss.
- Weather stripping – And/or insulation can also be installed on attic stairways or hatchways and on attic floor-mounted louvers for whole house ventilation fans. Review manufacturer specifications on the fans or recessed lighting fixtures if the additional insulation will adversely affect their performance.
- Ventilation – Without an adequate amount of ventilation, heat will build up despite the amount of insulation. Ventilation will also remove water vapor that can condense in the attic and result in dry rot and rust.
- Recommended venting is typically one (1) square foot of vent for every 150 square feet of the attic floor area. Smaller gable vents can be replaced with larger units.
- If the house roof has an overhang, or soffit, vents can be added to these soffit areas. A ridge vent can also be added. This vent is mounted along the length of the peak of the roof. The cold outside air that enters the soffit vents rises along the inside of the roof and exits through the ridge vent. This action cools the roof and removes moisture at the same time.
Other Methods for Prevention/Removal
- Snow Removal – Use a roof rake to remove snow from the roof. This action will help slow down an “ice dam’s” growth. Roof rakes work best if the snow is light and less crusty. Using a roof rake while standing on a ladder can be dangerous. Use caution. PLEASE NOTE: Roof rakes are designed specifically for the function of snow and debris removal. They are most generally available at your local hardware store. Be sure to use proper equipment to prevent damage to your roof. NEVER attempt to climb, stand or walk on the roof.
- Dam Modification – Cut out or chisel grooves into the dam to allow the water behind it to drain off. Exercise caution so shingles are not damaged as you cut into the dam.
Consult a licensed contractor for any necessary roof repair, vent installation or modification. Wear appropriate footwear for working in the snow and exercise extreme caution when using a ladder in the snow. Keeping your home free from Ice Dams is no accident. Be safe.
Take note of the topics and recommendations discussed in this bulletin. We encourage you to put them into practice – doing so helps ensure your safety. It is the philosophy of Frankenmuth Insurance and your Independent Insurance Agent to provide services that give policyholders peace of mind. At Frankenmuth Insurance, we truly are with you all the way.]]>