Icicles don't always mean ice dams. But they do mean snow is melting on your roof, and that some of the runoff is freezing into icicles as it trickles off the edge of your roof. It's this very “melting-and-refreezing” process that causes ice dams in the first place.

Can you have icicles without ice dams?

Like ice dams, icicles need cold temperatures, snow, and warmth to cause the snow to melt. Once the melted water comes in contact with the eave of the roof, the water again freezes. ... However, ice dams can be present without the existence of icicles.

Do large icicles mean ice dams?

Large icicles are too heavy to just attach to the roof. “The roof won't hold it up, it's rooted into a bigger problem, and that would be an ice dam,” he said. Because the ice dam plugs up your gutters, often you'll see water running down the side of the house. “That means you have an ice dam,” said Palumbo.