How to recognize and prevent winter ice dams

With recent severe and freezing weather, Paul Davis Restoration and Remodeling of Southeast and Fox Valley, Wisconsin, a leading provider of fire and water damage clean up and restoration services, is providing consumers with the following tips for recognizing and removing ice dams from homes and businesses.

Ice dams can form when a roof that is warmer than the eaves causes snow on the roof to melt, the water to flow down to the colder eaves, and re-freeze.

As this cycle repeats, ice can back up or “dam” under shingles, allowing water to accumulate behind it.

The water can leak through the roof and cause serious damage to walls, insulation, ceilings, and painted surfaces inside the home or office that may only get worse over time.

However, there are some relatively simple steps one can take to prevent ice dams:

Ice dams are caused by the interaction of many factors:

Ice and snow melt at 35°F. Liquid water freezes at 32°F. Minor temperature differentials can lead to major problems.

Layered roof systems such as shakes or shingles do not keep out standing water.

They require a continuous, uninterrupted slope to shed water.

Attics are warmer than the outside air because heat leaks from the heated portion of the structure up into the attic.

Heavy snow cover effectively insulates the attic from cold outside air, allowing the temperature to rise even higher.

When an ice dam forms and as layer after layer of meltwater refreezes, the ice dam can grow with liquid water pooling behind it under the snow.

Soon, this water is deep enough to seep between shingles and into the attic or wall cavities.

Ice dams are sometimes one to two feet thick. Secondary ice dams often form around vents and skylights.

One of the best methods of protection against ice dams is a properly designed “cold roof”. Minimizing heat gain in the attic while maximizing attic ventilation with outside air is one of the best ways to reach this goal.

Attics can gain heat in two main ways with conduction due to inadequate insulation; and convection caused by warm air leaking through gaps, usually around plumbing, wiring, ducts and vents. Try to reduce the conductive heat gain by increasing the insulation levels in the structure.

Convective heat gain can be minimized by meticulously caulking and sealing even the smallest penetrations through the ceiling, as well as carefully installing gaskets around attic entrances.

Although some heat gain is inevitable, when the attic ventilation is adequate, the temperature will not reach levels that cause extensive melting.

A cold roof is easy to achieve with properly designed new construction. Reaching the same goal in older homes may be both difficult and expensive.

Proper insulation is the key – attic spaces need to be kept cool so that the roof stays cold. Ideally, attics should have 12” of insulation.

Seal areas where heat can escape into the attic.

Likely spots include areas around chimneys, around electrical components such as junction boxes and ceiling fans, plumbing vents, and any other passages through the attic floor.

Ventilation – Less important than insulation but still a factor in preventing ice dams, proper ventilation will allow any heat that does enter the attic to exit the space and be replaced by cold outside air.

Unfortunately, obvious damage may be just the tip of the iceberg. The worst effects of ice dams are often hidden, caused by moisture trapped inside walls or floors. This damage is seldom discovered until months after all the snow has melted.

The property owner may seldom make the connection between the damage found and their ice dam of the previous winter.

Besides the cost of restoration, hidden damage can make future ice damming more severe, waste energy, and even create serious health risks for building occupants.

If an ice dam has already caused damage to the home or commercial building, it is critical to have the entire structure inspected by a restoration professional who is certified from The Institute of Inspection, Cleaning, Restoration Certification (IICRC).


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