Monitor risk of roof collapses under heavy snow loads.

As storms increase in severity, heavy snow has collapsed warehouse roofs across Alaska and Oregon. Flat and low-slope roofs have more risk than sloped or pitched roofs. Snow can accumulate quickly rather than shed.

Temperature matters

In addition to roof type, air temperature. When the air temperature is below freezing, one sq ft (0.09 m2) of dry snow weighs about three pounds (1.4 kg).

On the other hand, when the air temperature is above freezing, snow can partially melt. One sq ft (0.09 m2) of wet snow can weigh between 12 and 21 pounds (5.4-9.5 kg). That’s 4x – 7x heavier than the same amount of dry snow. Depending on the age of a building, snow loads can expose decades-old design flaws or warping of materials.

Some people may argue that a roof collapse can occur without warning. However, modern snow sensors can help protect your people and property damage.

Preventative measures

• Regularly evaluate your building for structural safety.
  The assessment can identify aging and non-snow-related damage.

• Deploy a network of total precipitation rain gauges.
  Also known as weighing rain gauges, this compact weather sensor continuously measures mixed precipitation within a wide temperature range. A smartphone app displays real-time data to inform maintenance teams when to remove snow.
• Set up snow pillows on the flat roof.
  Commonly used in the Alps, the SSG-2 snow scale precisely measures snow water equivalent in snowpack. In other words, it empowers you to monitor if the snow accumulating on your commercial roof is drier or wetter. The snow pillow is about 9 ft x 8 ft x 0.33 ft. Depending on the size of your roof, you may install a few snow pillows to monitor the density of the snow.

Monitor snowfall to mitigate the risk of roof collapses. Prompt and proper snow removal can avoid the build-up of excessive snow.