What could be nicer than being safely home on a winter’s day, enjoying a cup of hot chocolate while snow falls outside your window? That is until you hear the drip, drip, drip more often associated with a rain event and find that the pretty snow from outside your home has transformed into the leaky headache inside your home.
Snow build-up and ice damming on rooftops are a leading cause of winter season woes: causing water damage inside a home or building. Water infiltration not only can damage the contents of your home but can also cause delamination of the roof sheathing and wood rot of the building’s rafters and framing, creating a structural safety issue. It also causes attic and wall insulation to fail, which can increase heating bills substantially. Furthermore, wet insulation is a prime location for the development of mold growth, which can lead to a number of health problems such as asthma, allergies, colds and sinus conditions. With so many risks, it is important to understand the causes and prevention methods for snow build-up and ice damming.
It’s Not a Snowman
Snow build-up occurs anywhere that snow can accumulate on a roof and remain without sliding off, such as valleys and on flat roofs. The most common area of concern is wherever a vertical wall exists, such as at a chimney or the junction of a step-up from a lower roof to an upper roof. The vertical wall creates a space for snow to sit for extended periods of time and to extend up above the step flashing installed during standard roofing construction, which generally reaches only a few inches up the vertical wall. If the building paper is not installed correctly, the problems are further exaggerated. As the snow melts, the moisture can travel behind the siding, dripping down the inner wall behind the step flashing and into the building. The same problem occurs behind chimneys whenever the snow builds up higher than its crickets.
What is an Ice Dam?