Snow Loading Alert
Heavy snow and ice accumulation is a severe threat to municipal and school buildings. In the winter of 2011, roof collapses caused over $3 Million in losses to CIRMA members. Beyond the possibility of a major property loss, a sudden roof collapse can kill or seriously injure occupants of the building.
Older buildings, flat roofs, carports, garages, barns, and sheds are the most vulnerable to collapse from heavy snow and ice accumulation. There is only one solution: the removal of as much snow as possible by sending employees onto building roofs or by contracting a third party to remove the snow. Each option presents significant risk to CIRMA Members for Workersâ€™ Comp claims or from third-party liability. If you choose to hire a third-party vendor, please consult this guideline for Risk Transfer best practices.
How much snow can a roof hold?
If the building is relatively new, the snow load rating may be found on the building plans. If the building is older, a professional may have to be consulted. Roofs of most older buildings were built with little or no insulation, so snow melted fairly quickly. If insulation has been added, snow and ice wonâ€™t melt as rapidly and snow loads will accumulate to greater weight levels, further fatiguing the aging structure.
Unfortunately, there is no easy way to determine how heavy a snow load is. Dry, newly fallen snow may weigh 7-10 pounds per cubic foot; thawed and refrozen snow may weigh up to 60 pounds per square foot. Rain water will add even more weight. So structural engineers recommend taking several cubic foot samples of snow and weighing them, rather than measuring the depth of the snow, to calculate the weight on a roof. Further complicating the calculations are drifting snow, which may put excessive loads against equipment or penthouses or at walls between roof levels. Fortunately, few roof failures occur without some warning signs.
- Severe roof leaking.
- Ripples or bends in steel roof supports. Also cracks in wooden members, rolled or bent metal purlins.
- Sagging ceilings or roof lines. Note: a suspended ceiling may hide these sags.
- Cracks appearing in walls or ceiling. Again, a suspended ceiling may hide these cracks.
- Loud popping or cracking noises from the building structure.
- Ponding of water on the roof in areas where it never accumulated before.
- Obvious deformities in the roof.
Roof Snow Removal
If you think there is too much snow on your roof, the solution is to remove it as soon as possible. One way is to physically get up on top of the roof and push the snow off with a shovel and/or broom. This approach poses serious safety concerns. It's important to use ladders, safety ropes and take all necessary precautions (see section below). Snow rakes also can be used to remove snow. When using a snow rake, use extreme caution when working near overhead electrical power lines. Also, avoid excessive scraping on the roof or trying to chip off the ice. This can damage the roof. To clean the roof, as quickly as possible:
- Remove snow and ice from drains or drainage devices first.
- Remove drifted and unbalanced snow loads first.
- Remove snow in strip patterns, starting at the drainage device and proceeding up the slope. Remove snow strips. The goal is to reduce the load: the snow and ice do not have to be completely removed.
- Take care when you remove snow at the base of walls.
- Use plastic shovels and plastic tubs for lowering the snow to the ground.
- Protect and barricade areas where snow will be dumped or lowered.
- Donâ€™t use snow blowers.
- Donâ€™t pile snow on the roof.
- Donâ€™t use picks, hammers, spud bars or other sharp tools to remove ice.
- Donâ€™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.
- Donâ€™t block exit doors or fire exits with snow dumping or stockpiling.
OSHA standard 1926.501 requires fall protection for employees on elevated working surfaces. Each employee on a walking/working surface with an unprotected side or edge which is 6 feet or more above a lower level "shall be protected from falling by the use of guardrail systems, safety net systems, or personal fall arrest systems." Please see OSHA's Fall Protection for more information.
In general it is best to have a fall-protection plan already in place and to conduct general fall prevention training on a regular basis.
Please contact your CIRMA Risk Management Consultant for further information or additional risk management services.
To report a property loss, please use any of the following phone or fax numbers or email addresses below:
CIRMA Switchboard: 203-946-3700
Claims Fax: 203-773-8134
Cathy Gambrell, Liability-Auto-Property Claims Manager
Fax: 203- 497-2422
Cynthia Mancini, Liability-Auto-Property Claims Manager
Brenda Gillis, Sr. Property Claim Representative
All Workers' Compensation claims should be reported online at NetClaims.net. (If you are not registered to report online, claims may still be reported at 1-800-OK CIRMA.)