Snow and Rain: A Recipe for Disaster

When it comes to winter property maintenance, snow, followed by rain, is one of the worst combinations you can face. The problem with rain or wet snow following a deep snowstorm is that the rainwater gets trapped in the snow rather than pouring off the roof. The increase in weight can be dramatic. Plus, the weight of snow varies depending on the temperature and moisture content. Roof damage from heavy snow loads and ice dams is a significant cause of property loss. Rainfall on top of snowmelt can significantly increase the intensity of floods, and a sudden roof collapse can seriously injure or kill building occupants. When heavy rain occurs on top of snowfall, it can also significantly increase the likelihood of damage to the interior of your buildings.

Signs of Danger

Fortunately, few roof failures and floods occur without some warning signs; beware of:

1. “Ponding” of water on the roof areas
2. Ripples or bends in steel roof supports
3. Cracks in wooden members or rolled or bent metal purlins
4. Sagging ceilings or roof lines–note: a suspended ceiling may hide these sags, so remove the tiles and look above them
5. Cracks appearing in walls or ceiling–again, a suspended ceiling may hide these cracks
6. Loud popping or cracking noises from the building structure. (A laminated wood beam in one school broke with such force that personnel reported hearing what sounded like an explosion)
7. Obvious deformities in the roof

Snow Removal / Flooding Prevention 101

Here’s what you can do to help mitigate flooding and structural damage:

1. Regular cleaning and clearing of roof scuttles/drains – having these areas clear of debris will increase the likelihood of water flowing freely off the roof
2. Inspect roof flashing–many leaks are related to damaged flashing–and repair if necessary
3. Check interiors for water stains on the inside and outside of walls and parapets; repair any leaks
4. Inspect and clear drainage ditches, swales, and run-off areas of debris and accumulated silt so rainwater can flow freely away from buildings
5. Inspect sump pump systems; augment or repair and replace if necessary
6. Remove snow and ice from drains or drainage devices
7. Remove drifted and unbalanced snow loads
8. Remove snow in strip patterns, starting at the drainage device and proceeding up the slope; the snow and ice must not be removed entirely
9. Use plastic shovels and plastic tubs to lower the snow to the ground
10. Protect and barricade areas where snow will be dumped or lowered
11. Don’t use snow blowers
12. Don’t pile snow on the roof
13. Don’t use picks, hammers, spud bars, or other sharp tools to remove ice
14. Don’t use hot water pressure washers to remove snow from the field of the roof—this water generally freezes before it drains from the roof, adding to the weight
15. Don’t block exit doors or fire exits with snow dumping or stockpiling

It is also recommended to have coverings on hand that can be used to mitigate further damage in case of a leak.  These covers can be used after the storm to prevent additional water from intruding into the building. Preparing for a winter weather event can help prevent significant damage to municipal and public school properties.

CIRMA members are encouraged to “prepare to prepare” by addressing the fundamental readiness of their facilities to weather any storm successfully. Please get in touch with your risk management professional with questions or for more information.