Next time you drive around, look at how many homes have icicles coming off the roof. You will probably notice that older homes seem to have all the icicles and the newer homes have little to none. There is a reason for this. Before I knew anything about building science, I never really thought much about icicles or that they might be causing problems.
The truth of the matter is, icicles can be causing damage to your home, not to mention verifying the fact that your home has inadequate attic insulation, air sealing and attic ventilation.
What is the cause?
- Inadequate or no insulation in your attic.
- Inadequate or no air sealing between your conditioned space and the attic.
- Inadequate attic ventilation.
When we get snow accumulation on the roof top, we don’t want the temperature of the attic to melt the snow. A home with inadequate insulation and air sealing will cause too much heat in the attic. If the temperature in the attic is above freezing the snow on the roof will melt. The melted snow will then run into the gutter. Since the gutter is not being heated by the attic, the water will then freeze, causing an ice dam. As the snow keeps melting, the ice dam gets bigger and bigger. The ice dam will build up onto the roof and wont fully refreeze since its being heated by the attic. The ice and water will push up under the shingles and cause damage. A properly vented attic will help some of the warm air escape, but is not a complete solution to the problem.
Air sealing is tough to do on an existing home unless it is done prior to adding insulation. Icicles and ice damming can, in most cases, be solved by adding insulation and properly venting the attic. If you have this problem we recommend having these issues addressed sooner than later.
Ice damming is something we see in the field all the time. A great way to uncover these types of issues is by getting an Home Energy Audit.