Icicles are signs of trouble as snow melts off roofs

Icicle lights hanging from your house: Pretty.

Actual icicles hanging from your house: A sign of potential trouble.

Conditions were ripe this week for the creation of ice dams on houses.

According to the National Weather Service, ice dams occur when snow buildup melts during the warmer daylight hours, rolls down a roof slope and refreezes when it hits colder air.

If your gutters are blocked or you have a poorly insulated area at the edge of the roof, an ice dam can form when the water refreezes. The dam could result in water forcing its way up under the roof shingles and potentially leaking into your home.

Overflowing snow melt can also form icicles, which can be dangerous. Big ones have been known to pull gutters right off a house.

Why dams form

Of course, you should have cleaned your gutters and downspouts before winter arrived to ensure water can continue to flow.

You should also evaluate the insulation and ventilation in the attic of your home. The weather service recommends using insulation with an R-value of at least 30, but says R-38 is preferred in northern climates.

In addition, you need good airflow along the underside of the roof at the eaves or soffits to send air out to the roof vents.

The insulation will help keep heat from escaping from the interior of the house. The venting keeps the attic cool to minimize the freezing/thawing cycle on the roof.

What to do now?

But let’s say you forgot to clear the gutters of leaves, pine needles and other gunk, or they became packed with snow. Or that you can’t get a contractor out right away to do that insulation and ventilation work. What can you do right now to reduce the destructive potential of ice dams?

The weather service recommends trying to keep the snow on your roof to a minimum by using a roof rake to pull some of it off. Long-handled roof rakes enable you to stand on the ground, not a ladder, to safely do this.

It also recommends removing icicles. It does not say how.

Weekend weather

The problem is not going away soon. The weather service is forecasting that about 2 inches of snow will fall this weekend, and temperatures will remain below freezing until Tuesday.