A common winter problem with sloped roofs is accumulation of ice at eaves. When this ice causes water backup onto the roof it is commonly referred to as “Ice Damming” and in some instances can result in significant water damage as this water penetrates the roof. These ice accumulations are generally the result of snow melting on higher portions of the roof slope over the attic and the melt water freezing once it reaches colder portions of the roof slop, such as over the vented soffit.
With the increasingly complex roof configurations incorporating multiple slopes and dormers on many new buildings, the configuration of the roof is becoming greater factor in the ice damming equation. On a complex roof, portions of the roof will receive sun while other segments are shaded and colder. Snow melting on the sunny portion of the slope melts and refreezes on the shaded lower portion.
Correction of ice damming involves two aspects of work. The first is to reduce the conditions under which now on the roof melts. This can be accomplished by reducing the attic temperature by increasing ventilation of the attic or increasing insulation levels in the ceiling.
The second aspect of work is to ensure melt water can drain and does not re-freeze on colder portions of the roof. On a complex roof this may require the installation of heating cables to ensure paths of drainage are open.
If you are experiencing ice accumulation on your building’s roof, let our building science services team help you figure out the best course of action. Email us here or call 1.888.348.8991.
