What Causes Ice to Build Up on My Roof?

Poor Insulation

• Poor insulation often leads to ice dams, which are ice accumulations on the edge of the roof. The escaping warmth from the roof melts snow and sends water flowing down the slope of the roof. Once the water reaches the area of the roof above the overhang, which is not warmed by escaping heat, it freezes. This leads to a ridge of ice around the base of the roof. Continuing cycles of freezing and thawing add to the roof ice.

Roof Vents

• Chimneys and roof plumbing discharge warm air. Small pockets of ice form around these fixtures and increase in size over time. This type of ice buildup usually does not cause harm to the home unless the ice accumulation is large enough to seal the chimney or vent.

Sunlight

• Sunshine on a roof melts the snow, and usually the water will flow off the roof without problems. Difficulties occur when the shade of a building or an evergreen tree covers part of the roof. The water freezes on the colder part of the roof, and ice accumulates over time.

Preventing Damage

• Proper insulation of the roof limits heat loss and prevents ice dams from forming. Other options include removing snow from the lower sections of the roof with a roof rake, which consists of a piece of flat metal attached to a long aluminum pole. The rake user can remain on the ground while pulling off layers of snow. This allows any melting snow to flow off the roof and prevents ice buildup.