Here are some answers to questions about ice dams that have arisen lately:

What is an ice dam?

An ice dam is a buildup of ice, water, and snow near the eaves of a roof in winter.

What causes an ice dam?

A poorly insulated roof, plus extreme temerature swings common in late fall and early spring, cause snow to repeatedly melt and freeze. As the blockage of ice at eaves increases, newly melted snow can't run off, so it contributes to the growth of the ice dam.

Are ice dams always bad?

If your roof develops ice dams frequently when other nearby buildings don't, your roof is probably poorly insulated, which should be addressed. However, during extreme weather cycles any roof can develop an ice dam.

Do ice dams always cause water damage?

No. A properly installed roof should not leak even if it develops an ice dam. Low quality underlayments and poor installation practices are the root cause of most damage from ice dams.