Roof Raking and Snow

[Thor_MN]

5. Ice dams usually occur at the eaves.

Heat escaping from the heated space of the house melts snow drips down to the unheated eaves and refreezes. If enough ice builds, then you eventually have no slope to the roof at the eaves and the melted water pools up behind the ice dam. That water will find a way through the roofing and into the house.

If your house creates ice dams, adding insulation/ventilation to prevent the ice dams is the best route. Roof raking should be to prevent a heavy snow load from collapsing the roof.

Your uninsulated garage is actually at less risk for ice dams, as there isn't much heat to melt snow.