Snow on the Roof A Potential Costly and Dangerous Condition

 The winter months bring us a more heightened awareness of what a major snowstorm  can do to our commute to school or work and, our voicemails if we are a  property manager. However, with the heavy snow comes a very real potential for structural failure  of a condo association’s roof system that may have tragic results.  

 We have all seen on the news where a roof has experienced a complete or partial  collapse after a heavy snowstorm. The cause, referred to as, “excessive snow load” can result in significant structural and property damage and may result in  injury.  

 Typically, it is only a report of a water leak that brings attention to our  roofs in the winter months. Many times the leak is the result of ice damming in the gutter or melting snow  entering into a vent. However, sometimes the leaks may be from movement of the  structure due to the weight of the snow and ice.  

 On steep sloped roof systems, excessive snow loads are usually the result of  wind creating large snow drifts but they also may be from large accumulations  of wet snow from one or several storms. Excessive snow loads most often occur  in valleys or at a stepped location against a wall. Additional snow load as  well as an impact load with force can also occur when snow or ice slides off a  sloped roof onto a lower roof.  

 These scenarios can create concentrated loads on roofs that are well in excess  of the loads imposed by uniformly distributed snow and that may exceed the  design loads. Winter rain storms after a snow event and resulting ice  accumulation can further increase roof loads and the associated risks. It is  important to realize that that each roof has its own unique characteristics and  design standards for snow loads. Remember, only an expert with experience  calculating snow loads and design of roof structures should design a roof  system or assist with a particular repair.  

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