Heading off ice-damming on roofs

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Unless you’ve spent the last few months in Arizona, Florida or some other warm locale, you couldn’t help but have noticed the drubbing that this winter has perpetrated on the Midwest.

And one of the direct victims of this barrage of ice and snow has been roofs, both the home and garage variety.

Darius Margis, president of Promar Roofing in Orland Park, said one of the biggest problems is “ice damming,” which occurs when melting snow on a roof runs off and refreezes at the edge of a roof and creates a pool of water under the shingles. A problem heard much about this winter.

Margis said damming occurs when the snow is melted by a warm roof, forcing water to flow between the snow and the warm roof surface, then freezing and turning to ice as it gets past the exterior wall and hits a cold unheated roof edge or gutter. As the bottom of the snow pack continues to melt, water continues to flow down the roof surface until it hits the ice, thereby creating a larger and larger ice dam.

The larger the ice dam the greater the chance that ice can work its way back up the roof, getting under shingles, melting and leaking into the exterior wall, home or attic.

Margis said ice dams also tear off gutters, loosen shingles and cause water to back up into the home. He said he sees the widespread signs of ice damming as he drives around in the winter: Sheets and sheets of icicles hanging off roof after roof along each block.

Causes of ice-damming

Margis said the cause of the (ice-damming) problem comes down to two things: Poor roof ventilation and warm attic space. “Those are the two biggest factors in preventing ice damming,” he said.

Margis said that warm attic spaces occur because of inadequate outside air circulation (ventilation) through the attic (soffit to roof ridge), which is necessary to keep the roof deck cold. He said attic warming from poor ventilation is made worse with the introduction of heat from the space below the attic.

Preventing the damage

He said the attic temperature should be the same as the outside air temperature.

“If you have adequate insulation and air ventilation, you can prevent 90 percent of ice damage on your roof,” Margis said.

He said most roofing shingles “work” the same but some will last longer than others.

Margis said roofing shingles can last up to 50 years, but those will cost more than the ones expected to last 20 to 30 years. “Those shingles (expected to last up to 50 years) are made with better material and are a little heavier than the other ones,” he said. “They can also withstand winds of up to 170 mph.”

Margis said Promar provides a five-year labor warranty on its work.

He said to prevent ice damming from occurring, Promar installs a rubberized water shield that is affixed to the wooden deck and under the shingles near the edges of the roof to keep water from getting underneath. He said the inclusion of the water shield is mandatory as part of the Illinois Roofing Code.

Margis said homeowners should check to make sure roofing companies provide the water shield as part of the roof work. He also said homeowners need to make sure roofing companies are licensed and bonded.

More information about Promar Roofing is at www.promarroofing.com.