Last week’s storm and the weekend’s frigid temperature are history. This week, we look ahead to higher temps, even rain, and another drop back to freezing. Watch out Wilton, the weather is inflicting torture–and it could do even worse damage to your home in the form of ice dams.

Ice dams are a big problem that can form if the conditions are right–when temperatures plummet after heavy snowfall, only to cycle back to thaw and refreeze, ice dams may form causing water to accumulate and back up under shingles, into ceilings and down into walls.

Tell-tale signs that there may be an ice dam problem are ice ridges that build up along gutters and roof eaves. Icicles hanging along the gutters may look pretty, but they’re also a sign that something more nefarious could be hiding beneath the rooftop snow. (Depending on roof design, they may form elsewhere as well.)

Other clues homeowners can also look for are water stains or moisture in the attic or along the ceiling of exterior walls of the house, which may be an indication that an ice dam has formed and water has penetrated the roof membrane.

According to Steven Gidley of Wilton-based ABC The Roofing Experts, there are two types of weather conditions that cause ice dams when there’s a lot of snow on the roof.

The first occurs when there is internal heat leakage from the house through the attic because of no insulation or poor insulation. Warm air inside the home leaks into the attic, and melts the snow from underneath. Well-insulated attics are a great preventative step, but are not always 100% perfect at stopping ice dams from happening–warm air may still get past that insulation.

The second cause is what Gidley calls the “classic condition” for ice dams:  heavy snowfall and severe cold, followed by a couple of warm, 40-50 degree days with potential for melting snow, followed by or interspersed with temperatures that drop back down to freezing.

“Now what you get is melting-thawing-freeze; the next day melting-thawing-freeze. It’s called the ‘freeze-thaw cycle.’ That is when the ice freezes in the gutter running down the roof and the gutter can’t drain it. It builds up on the edge of the gutter, and can get from two- to 13-inches high,” Gidley says. “As soon as it starts to build up on the gutter, no more drainage can occur and it actually creates a little pond behind the ice dam, about a foot or two up the roof. These ponds freeze at night, and they add to the ice dam height, pushing the water back up the roof further under the shingles and gets to the nails, which are the pathway into the house.”

With last week’s snow from bomb cyclone Grayson, coupled with the weekend’s deep plunge in temperatures, and any projected daytime-thawing-nighttime-freezing we’ll likely see later in the week, Wilton is looking at the classic ice dam situation.

Gidley does say the freeze-thaw cycle needs to continue over two or more days. “On the second or third day it starts coming into people’s houses, because it comes in and down through the wall, and drips through the kitchen ceiling lights. If it’s really bad, it will come through the ceiling in the bedrooms, which means it’s coming in higher, at the 2-3 foot level up the roof.”

If even more snow falls, all bets are off.

“If we get another snow load up there, on top of what we’ve already got, we’ll have a pretty virulent ice dam season for maybe two or three weeks,” he adds.

What to Do

One remedy that people should consider is to use a roof rake to rake off about three feet of the snow from the roof. Gidley recommends doing it–or having it done by a professional–right now, before the ice dams form, ideally through this Wednesday, Jan. 10.

Wilton Hardware (21 River Rd.) has roof rakes in stock, but only one model–an all-aluminum version at 21 ft. long, for $68.99. Store owner Tom Sato says he prefers the all-aluminum version because it holds up better under use. “As ice begins to form under the snow the users tend to slam the blade down on the roof to try and break up the ice and poly blades tend to break sooner than the aluminum blades.”

Gidley says the safest thing to do is hire a reputable roofer or contractor to help remove ice and snow from the roof, especially if it’s already leaking. He adds that homeowners should definitely make sure the person is insured and qualified.

People might want to consider taking steps now because contractors will get busy. “If we get another snow and multiple snow loads, and a freeze-thaw cycle, that’s going to create an unprecedented ice dam situation,” he says, although most likely not as bad as what happened in 2010-2011, a year many Wilton homeowners got slammed with ice dam damage. That year, Gidley says, there were 185,000 ice dam insurance claims filed across the country.

There are longer-term solutions, like having heating cables installed and making sure that insulation is sufficient and adequate. Gidley also says it’s important to maintain your roof.

“The most important thing is not have a roof system that doesn’t have a properly installed ice and water barrier system, with preventative ice lock flashings and preventative water barriers–then it’s not going to come in the house and then you don’t have to do anything.”

Steve Gidley can be reached at 203.223.7725.