How ice dams form
An ice dam starts on the roof, not in the gutter. Heat from the house warms the upper roof, snow melts and runs down to the cold eave, and it refreezes there. Day after day the ridge of ice grows, and melt backs up behind it, sometimes under the shingles and into the house.
Where gutters make it worse
Sectional gutters are joined every few feet. Each joint is a place for meltwater to drip out instead of running to the downspout, and those drips freeze into the icicles and ice sheets you see along the eave. Ice is heavy, and it pulls on loose hangers until the gutter tips forward and spills over the back.
What actually helps
Seamless gutters keep the melt moving: no joints to drip, and heavy-duty hidden hangers that keep the gutter tight to the house. Bigger 4×3 downspouts help on large roofs.
The real fix for ice dams is keeping the roof cold: good attic insulation and ventilation, with air coming in through vented soffit and leaving near the ridge. A metal roof sheds snow better than shingles, too. At a free estimate we’ll look at all of it and tell you honestly what will make a difference.