The story of our lives up here in the great white north these days revolves around weekly storms dumping large amounts of snow, wreaking havoc on roads, causing problems for schools and leaving homeowners with major removal problems. While getting rid of snow in our driveways and yards is a pain in the neck and back, removing snow from the roofs of houses is critical to to avoid damage, leaks and possible collapse.
An ice dam forms when there is snow on the roof and higher portions of the roof’s outside surface must be above 32°F while while lower surfaces are below 32°F. The snow of the roof surface that is above 32°F will melt. Melted snow will run down the roof and when it reaches surfaces below 32°F it will freeze creating an ice dam. The dam will continue to grow by being fed from melting snow. Water will pool behind the dam and find its way into cracks and crevices, freezing and melting causing roof leaks which can lead to major damage to your house and possible collapse of the roof.
Temperature differentials are caused primarily by heat loss from inside of the house. Although there are rare incidences where solar radiation and reflection may contribute. Heat will travel from inside the house to the roof by either convection, conduction or radiation:
Conduction is when heat travels through a solid, this is the way a cast iron pan heats up; heat moves from the source at the bottom up through the pan.
Convection is how the air is heated above the solid; just above the frying pan the air heats up, rises and is carried off.
Radiation is heat transfer via electromagnetic waves; this is how we feel the heat from the sun.
In our houses the heat moves via conduction through the ceiling and insulation to the slanted portions of the ceiling where there is usually not much space available. The top surface of the insulation will be warmer than its surroundings which heats the air above then carrying the heat by convection to the roof. The high temperatures of the surfaces of insulation radiates heat to the comparably lower temperatures of the roof. Adding insulation can reduce heat transfers via convection and radiation.
Ice dams should be prevented where and when possible by controlling heat loss from the house and removing snow each storm to prevent build up and melting. Roof ventilation is also critical to controlling and stabilizing uniform roof temperatures. However the time for making improvements to your roof or ceiling insulation is not ideally during the winter, especially one as cold and snowy as what we are currently experiencing. Right now we have to focus on removing as much snow from our roofs as possible to eliminate additional loads which may not be bearable and can cause collapse and reducing the possibility of structural and aesthetic damage due to leaks. Excessive deep snow, high roofs and physical strain prevent many people from removing snow from their roofs as often as necessary or at all, SavATree and your arborist may be able to help. Equipment normally used for pruning and taking down trees can be utilized to reach previously unreachable heights for snow removal, clearing of ice dams and reduction of the burden put on drainage systems and gutters. For more information about SavARoof contact your arborist immediately and visit http://www.savatree.com/savaroof-snow-clearing.html.