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Ice on your roof?

Ice on your roof? A major problem that often has a quick fix.

If you notice ice forming at the edges of your roof, often accumulating where guttering may be installed, this is a symptom of a larger problem. It is your home’s way of telling you that your attic is not breathing properly. Heat from inside the home, is escaping into the attic, and as this hot air rises in the attic it will warm the underside of the roof. This will result to melting the snow that is sitting on top of the roof into water and this water will trickle down the ‘warm’ roof. Once the water reaches the edge of the roof where it is no longer warm, it refreezes and turns to ice. Although, the ice itself will make your roofing shingles decay more rapidly and may also result in some water infiltration in the future, the root problem of a suffocating attic can also cause other major problems like condensation and mold inside the attic itself.

In the example above, the warm air escaping into the attic warms the underside of the roof and melts the snow above, but inside the attic, this warm air may condensate as it cools on the underside of the roof. This condensation creates moisture and if the attic is not breathing properly, this moisture has a hard time drying out and can result in mold.

So, you have ice on your roof in the winter and now you’re worried. How do you address the problem and fix the issue?

When we are addressing this issue we always want to keep this simple rule in mind; an attic should always be the exact same temperature as outside. When this is the case, the snow on your roof will remain snow until the outside conditions melt it. In order to achieve this, two factors must be put into place. One, you have to ensure proper airflow from outside to inside and back to outside the attic. A constant flow of outside air gives your attic the chance to be the right temperature. Two, you have to insulate your attic sufficiently so that the heat (or cold, when we are cooling the air in the summer) from inside your home does not escape into the attic. If these two factors are in place, your attic’s temperature will match outside’s and their will be no signs of ice or condensation. Your attic will be ‘healthy’.

Taking all this into consideration, if you are having ice problems, the first thing you should check is if you have proper airflow from outside to inside your attic. Are your soffites perforated with holes? If yes, are they unable to breathe because they are blocked from the inside with insulation lying on top of them? Do you have a roof ventilator installed on top of your roof? Ideally, air should be flowing into the soffit vents around your roof and then escaping through the roof ventilator installed on top of the roof. View the illustration for a visual.

graphic explaining proper attic ventilation

Now that you fixed your airflow issue, next step is to make sure you have adequate insulation installed on the attic floor to keep the heat (or cold conditioned air in the summer) inside the home. Proper vapour barrier and an insulating factor of about R40 should do the trick.

In conclusion, ice on your roof in the winter means a lot more than simply ice on the roof. It is the sign of an underlying potentially major problem and whether you address the issue yourself, or decide to contact a contractor to take care of it for you, make sure it gets sorted out. This is not a pricey fix if treated quickly enough, but if it goes on too long without being addressed it can result in major problems down the line.