We have all encountered ice dams. They are the ridges of ice that form at the lower edges of some rooves. As snow melts above them, they can prevent water from draining properly, causing water instead to pool and leak into the home - in turn causing damage to ceilings, insulation, and other areas.
In turn, causing homeowners quite the headache!
The particular causes of any given ice dam issue can be quite complex. But in general terms, an ice dam results when snow is on the roof and the roof temperature is above freezing at higher roof sections and at or below freezing at lower roof sections.
When this dynamic is in place, the snow above melts, descends the roof a bit, and then freezes in place once reaching the lower, colder section.
We have found that the only way to cure an ice dam – and prevent one in the first place – is to:
1. Seal all points where warm air leaks from the living space into the spaces immediately below the roof sheathing. Note that this is not always possible using visual inspection alone. To be sure areas are well sealed it is often key to diagnose leaks and test intended improvements by operating a blower door and infrared camera.
2. Insulate the living space well enough to prevent conduction and convection of heat through the ceiling. To ensure insulation is installed uniformly, again, blower door testing and use of an infrared camera is best practice.
3. Consider venting options between the space between the insulation and the roof sheathing, so that any heat that does leak through is carried away.