Ice dams happen when snow on your roof melts due to warm air escaping from inside your home, rising to the top of your attic area. The snow at the top of your roof melts and the water runs down your roof under the snow pack. Once it reaches the overhang area (no more warm air from your home), it re-freezes and becomes an ice dam. The resulting ice dam now blocks further melted snow from running off your roof. Ice builds up in that area, resulting in possible water ingress and damage to your home. Take some time to prevent ice dams on your roof.
Prevent Ice Dams
The basic principle in preventing ice damming is to keep your attic-space air temperature the same as the outdoor temperature during snowy and cold weather. This will eliminate ice dams from happening in the first place.
Sealing any air leaks from your home into the attic is a good place to start. Also ensure you have adequate attic floor insulation balanced roof ventilation. Click on this link for more information on roof ventilation.
When installing your new roof, it is strongly suggested (sometimes required by local code) to apply two rows (24” total) of ice & water shield (aka peel n stick membrane) along the eaves and valleys. Then follow with regular underlayment over the remaining roof surface area, prior to installation of your chosen roof product. This is a good idea regardless of what type of roof product you install. Follow this protocol to provide extra protection against water ingress in the common ice damming areas of your roof.
Installing a metal roof that naturally sheds snow before it can form an ice dam significantly reduces the chance of ice damming on your roof. The best way to prevent ice dams is following the above recommendations for adequate insulation, adequate ventilation, proper underlayment and eliminating any heat losses occurring from your home, regardless of which type of roof material you have.