What is a roof dam?
It your first thought is that it doesn’t sound like it would be a good thing for your roof, you would be correct since its not. An ice dam is definitely something you will want to avoid for a few very good reasons which we’ll discuss in a moment. Probably the best way to explain what an ice dam is is to start by explaining what causes an ice dam first.
An ice dam is a result of two things.
The first is heat loss from the inside of your attic or home to the outside, due to poor insulation in your attic. Unfortunately a lack of insulation in homes is very common for a variety of reasons. In some cases the homes either never had enough insulation to begin with, or perhaps animals and rodents have entered the attic area and chewed through it. Water issues can also break down insulation as well over time.
The second is not having enough roof venting (which traps heat in your attic). Similar to the insulation issue mentioned above, it is very common for homes to lack proper ventilation on their roof.
To avoid having ice dams, it is vital that the temperature of your roof itself should always match the temperature outside. When roof is warmer than the temperature outside, due to either a lack of insulation or poor venting it can cause the snow on your roof to melt. When the snow melts, it runs down the side of your roof and collects near your eaves where the roof temperature is cooler. Now once the melting snow has run down the side of your roof it then re-freezes at the eave it creates, yes you guessed it an ice dam.
This is where things get bad.
As the ice expands at the ice dam, it progressively forces its way beneath the shingles on your roof and separates them. This not only creates a potential entry point for water, it also prematurely breaks down the integrity of your roofing.
So how do you avoid ending up with an ice dam each year?
Get your roof/ attic insulation topped up, and add proper ventilation. By doing this it helps keeps your roof surface temperature consistently cold with the outdoor temp which either reduces or completely eliminates the likelihood of ice damming.