Cleared for Safety: Here's How Much That Snow on Your Roof Weighs
The recent snowfall combined with extreme winds that can create drifts led the State Fire Marshal to warn New Hampshire residents to clear off roofs.
Fire Marshal J. William Degnan said Friday a roof may collapse with little or no warning.
Snow can weigh anywhere from about 5 pounds per cubic foot for the fluffy, light concentration to 20 pounds per cubic foot if it's saturated.
This means if you have a 1,000-square-foot roof, 2 feet of light fluffy snow is like having 10 moose stand on your roof. For 5 feet of snow, it's like putting a semi-truck on the roof.
The snow drifts can cause much higher depths on one part of a roof, creating an imbalance that makes the roof more susceptible to collapse.
Roofs are designed to bear a normal snow load. The State Building Code specifies what is considered a normal snow load for roofs in specific locations of the state.
Degnan gave the following tips for clearing your roof.
- Be careful not to damage your roof along or any gas or oil service-entrance or vent into the building below.
- Keep all chimneys and vents clear to prevent carbon monoxide from backing up into the building. You might have to dig them out after removing the snow from your roof.
- Keep all exits clear of snow.
Fire and building safety questions can be answered by local fire and building officials or the State Fire Marshal’s Office at 603-223-4289.