What causes Ice Dams and how to prevent them ?


What causes Ice Dams and how to prevent them ?

An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow from draining off the roof. The water that backs up behind the dam can leak into a home and cause damage to walls, ceilings, insulation and other parts of the house. That is why it is necessary to prevent ice dams.

Ice dam might form when…

– There is snow on the roof
– The average outside temperature is below 32°F ( 0°C)
– Roof surface temperature is above 32°C at its higher end and below 32°C at its lower end.


1- How do ice dams form ?

In order to understand how to prevent ice dams, it is useful to know how they form in 4 steps.

 1  Indoor heating rises through the ceiling into the attic and warms the roof surface.

 2  Snow on the heated part of the roof melts and flows down until it reaches that part of the roof that is below 32 degrees. Water freezes into an ice dam.

 3  The dam grows as it is fed by melting snow above but water held by the dam backs up and stays liquid.

 4  Eventually, the water finds cracks in the roof covering and flows into the attic, from where it could seep through the ceiling and interior walls.

NB: Pitched roofs are engineered to evacuate water, not to hold on to it. Even the best roofs are not warranted for standing water.

2- How to Prevent Ice Dams?

During another white and rough winter, your roof is covered with deep snow. Inside, the heating is working hard to keep your family warm. If your attic is badly insulated, the heat rises through the ceiling. These hot spots cause melted snow to fall down over the edge of the roof, into the valleys, or the gutters. This melted snow freezes into an ice dam. Thus, ice dam may be prevented with a good insulation.


3 – Do you have sufficient insulation?

Good insulation helps minimize the heat loss from the house into the attic. When you keep the heat in your home, you avoid hot spots and save money on the heating bills. Sufficient insulation plays an important role of creating a thermal protective barrier, separating the hot and cool spots in your home. Heat leaks inevitably force you to use more and more heat in order to achieve your desired house temperature. Verify the insulation thickness that is recommended for your area and ice dams can be prevented.

4 – Make sure your attic is well ventilated to prevent ice dams

A good ventilation of your attic means less variations of temperature between the different parts of the roof and its environment. The air entry by the soffits and the eaves is as important as the ridge vents to allow an exchange of air and avoid dam. Always keep soffits and air channel free from obstruction to prevent ice dams.


5- Avoid accumulated snow on your roof

By avoiding the snow to accumulate on your roof, you will more easily prevent ice dams. Indeed, the longer the snow stays on your roof, the more you might see an ice dam. Low pitched roofs, valleys, or skylights sometimes create this phenomena. Removing the snow from your roof can be hard and hazardous work. Houses with metal roofs usually don’t have this problem because of the shingles’ smooth surface that allow natural snow removal. Homeowners can enjoy peace of mind as they don’t have to manually remove the snow from their roof every winter.

Did you know?

Our permanent metal roofing system can help you to fix and prevent ice dam issues. Feel free to contact us for more information.

For more information about Kasselwood Permanent Metal Roofing System or for a free estimate! Contact Us !