What Causes Excessive Ice Buildup & Icicles on a House?

Poor Insulation

• A layer of insulation rests between the home’s ceiling and the open attic space between the ceiling and roof. When the insulation is poorly installed, worn or eroded, heat rises from the house toward the roof, where snow has accumulated. This causes the snow to melt, and the water will run down and get trapped in the soffit, gutter or corners of the roof. There, the water refreezes as the temperatures begin to drop again. According to State Farm, the optimum temperature for ice dams to form is 20 degrees Fahrenheit.

Full Gutters

• Gutters capture water as it drains and bring it down the side of the house to the ground so it does not accumulate on the roof. When gutters are full of debris such as leaves and excess dirt, a blockage forms that prevents water from draining properly. During the winter months, when snow melts throughout the day, water pools in the gutter rather than drains off the roof. As the temperatures cool overnight, the pooled water freezes, causing an ice dam.

Air Leakage

• Small holes in a ceiling or roof can allow warm air to escape the house and melt the snow on the roof, which can form ice dams. Use urethane spray foam, caulk or weatherstripping to prevent air leakage from areas prone to air leaks in a home, such as the kitchen and bathroom vents, plumbing openings, ceiling fans, light fixtures, chimney openings and ceiling intersections.

Prevention Don’ts

• You might be tempted to remove ice dams to prevent damage, but this can actually cause further damage to the home and pose a safety risk. Never chip away at ice or snow on the roof, because this can cause damage to shingles or cause sheets of ice to fall from the roof and possibly harm anyone standing by. Also, never place salt or sodium chloride on the roof to keep ice from forming; this will erode gutters, and runoff water containing the chemical can damage grass.