Snow, ice on roofs a growing concern
By Melanie Savage
Region - posted Tue., Feb. 1, 2011
Most of us have seen the headlines: “Hampton roof collapses, kills six cows” (News 8); “Numerous roofs collapse because of snow” (Eyewitness News 3). It’s unnerving, to say the least. Since the latest snowfall on Jan. 26 brought up to an additional 16 inches of snow to the state, weather-related woes have increasingly captured media attention. With a total snowfall of 59.8 inches, January 2011 has become the snowiest month for Connecticut, breaking the record (45 inches) set in 1945. But does all that snow really warrant getting up on your roof with a shovel? Seems a straightforward answer to that question can be rather elusive.
Locally, there haven’t been any major incidents. According to the Hebron Fire Marshall, the only roof collapse in town has been a large storage shed. A representative at the Columbia Fire Department said, “We had one partial collapse. It was a commercial building, the roof sagged, and they shored it up. The major problem people are having right now is with the ice dams.”
According to a University of Minnesota Extension online Housing Technology resource, “an ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow (water) from draining off the roof.” Ice dams cause water to back up under shingles, and can cause water damage to a home’s interior. The most common cause of an ice dam is snow cover that allows colder temperatures on the surface, with warmer temperatures below. Snow near the roof melts, hits freezing air on the surface, and freezes, causing a barrier. Roof temperature is related to a number of different factors, including insulation, attic venting, and ceiling structure (see www.extension.umn.edu/distribution/housingandclothing for an in-depth discussion). Whatever the cause, the result is water penetration.
According to Chris Royster, from C and R Contractors in Vernon, “we estimate that between 60 and 70 percent of residential buildings in Connecticut right now are experiencing leaking.” If you’ve got large icicles hanging from your gutter, there’s a good chance you’ve got an ice dam. That’s what brought contractor Peter Keklak to a home in Hebron. The owner had water leakage into the home, and hired Keklak to remove the snow. Keklak said that a common problem is the practice of raking the first three feet of snow off from the ground. “That just creates a wall of ice where you stop,” he said. Rakes are good for removing snow from the gutters, but Royster agrees that removing more isn’t a good idea. “Either have a professional remove all the snow, or leave it alone,” he said.
But if you leave the snow there, will your roof collapse? Probably not, but there are a number of different factors that determine the answer to that question. The engineers at the Institute for Business & Home Safety (IBHS) offer the following guidelines to help home and business owners determine how much snow may be too much for their roof to handle.
Keep in mind that newer structures may be designed to handle increased snow loads. The best source for determining how much snow load a building can handle is the design plan. These designs can range from between 40 and 70 pounds per square foot in New England. IBHS offers general guidelines to help estimate the weight of snow. Ten to 12 inches of new snow is equal to one inch of water, or about five pounds per square foot. Most roofs can handle up to 4 feet of new snow before there’s a concern. Three to five inches of packed snow is equal to one inch of water, or about five pounds per square inch. Anything more than two feet of packed snow could be dangerous. The total accumulated weight of two feet of old snow and two feet of new snow could be as high as 60 pounds per square foot. Ice is much heavier, with one inch equaling about a foot of fresh snow.
Bottom line, if you’re not experiencing leaking but you’re worried about the weight, use your own best judgment. But opinions are unanimous regarding another issue: getting up on your own roof to clear the snow can be extremely dangerous, and is best left to a professional. On top of the danger of injury, there is the danger of doing damage to your roof. Plastic implements are safest, and it’s best not to remove down to the surface; leave a protective layer and let the sun do the rest.
If your roof is leaking, it’s risky trying to remove an ice dam yourself. Call a professional. There is also a product called an ice melt sock that can be thrown onto your roof and pulled into place. The sock is filled with a deicer, and the manufacturer claims that it will melt through a dam without the need for climbing a ladder (www.snowmeltsock.com).