Preventing Roof Collapse Due to Snow

Michigan Winters! You never know what kind of weather we will have – heavy snow storms and accumulations and images of a winter wonderland or a unseasonably, mild, global warming conditions. However, we need to be prepared and know how to protect our buildings from possible collapsing and other damages that can occur!  Read the article below for tips & tricks to beating snow damages to your property!

Jennifer Moffitt, CIC, CWCA

 

Snow, ice and rain can add tremendous weight to roofs—causing them to collapse. The impact of roof failure can be long-lasting and traumatic. Extended shutdowns can lead to loss of customers and additional expenses. Roof collapses also can cause serious injuries and loss of life.

What’s the problem?
Flat roofs are particularly vulnerable to collapse and water damage, while metal roofing systems, steel decks and boards on joists have little ability to withstand and recover
from large loads of snow or rainfall due to their lighter construction. The main causes of rain or wet snow overloading are water “ponding” in low areas of the roof where adequate slopes to drains are not present … and drains blocked by ice, snow and other objects.
Snow drifting often becomes a problem with roofs with different sections at different heights, on the downwind side of sloped roofs, against parapets more than two feet high, and against penthouses or other roof structures. Ice weighs 57 pounds per cubic foot. Snow weights for different densities and depths are shown in the table above.

Conditions Leading to Roof Collapse

  • Common conditions that may make snow-loading more likely to cause collapse include:
  • Damage to roof structural members, indicated by sagging, cracks, corrosion, spalling (surface flaking on concrete) or efflorescence (white powdery appearance on concrete)
  • Roofs retrofitted with insulation, where snow may not melt as it had before
  • Parts of a building that are not heated for more than a day
  • New items added to the roof, such as AC units and solar panels (Because these items add weight, less snow is needed for the roof’s weight capacity to be exceeded.)
  • Canopies or lower roof units that have been added to the structure, because they often have a lower load capacity than the main building
  • Drains, gutters and downspouts that aren’t cleaned at least quarterly

Download the entire PDF here

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