Sergio Molina inspected three homes on Wednesday that showed signs of damage from rooftop ice dams.
Continuing snowstorms and freezing temperatures over the past several weeks in the Treasure Valley have caused stress to roofs above attics with inadequate insulation or lacking proper ventilation.
Heat rises from inside a houses and raises the temperature of the roof, causing snow to melt, said Molina, a project manager and estimator for Nampa-based Disaster Kleenup. Water then flows down the slope of the roof until it reaches a dam of ice along the eaves or the gutter, which is colder than the rest of the roof.
Some of that water freezes and adds to the wall. Another portion may drip off the side of the roof, forming icicles while water trapped above the dam can seep under shingles, causing leaks and damage to the roof itself. It could also cause mold inside and damage some types of insulation.
“Eighty percent of the people who call us don’t know what happened,” said Molina. “Suddenly they have a leak.”
Dan Kopp with Boise Valley Home Inspection said he viewed a townhouse on Tuesday with ice dam buildup. It was caused by too little insulation, he said.
Blown-in fiberglass insulation should be at a depth of 13 to 15 inches, Kopp said. The townhouse he inspected averaged 4 inches across the attic.
“If you see icicles hanging from the edge of your roof, that could be a sign of an ice dam forming,” Kopp said.
Most of the homes where Molina finds ice dams were built in the 1990s or earlier. Modern homes have better insulation and do better to keep warm, moist air from reaching the attic, he said.
A roof rake used to remove snow can prevent an ice dam from forming and give melting snow a way to reach the gutter. A plug-in heat tape, which has to be installed before snow falls, can raise the temperature along the eaves to prevent dams.
Experts don’t recommend using a hammer or other tool to try to chip off ice that has already formed. That, they said, could damage the roof and require costly repairs.
Both Kopp and Molina recommend that homeowners keep a close eye on their roofs.
“The sooner they address it, the better,” Kopp said.