inter is off and running in Alaska, and the National Weather Service is predicting this to be an El Niño season. Alaskans should expect above-normal temperature and precipitation along the coast and above-normal temperature and below-normal precipitation in the Interior, especially throughout the winter. Many regions received early October snowfall, and a Snotel [snow telemetry] site near Thompson Pass had already measured 19 inches on October 12.
If your company does not already have winter snow removal plans in place, this would be the time to start. This should include a formal maintenance plan for roofs, especially in regions of the state that traditionally see higher snowfall.
In Anchorage, 6 feet of snow fell between December and February. It was the ninth time on record since the early ‘50s that the city had seen more than 100 inches of snow in a single season. Buildings began collapsing in February under the stress of accumulating snow and ice. Sadly, a Midtown building collapsed on February 18, killing one person and trapping two others.
March had multiple snow events throughout the month. Into April, blizzard warnings continued through many parts of Alaska. April broke the all-time record of 31 inches of snow for the month in Anchorage. By the time the month was done, sixteen buildings in the city had collapsed.
Historic weather data in Anchorage show that the record snowfall year was the 2011/2012 winter season, with 134.5 inches recorded and the coldest January in Alaska’s history. It also had one of the most ferocious storms to hit the Bering Sea in twenty-five years, with 35-foot waves and a storm surge of 8.6 feet that pounded Nome for days. That season was also an El Niño season.
Preparing for these winter seasons takes a combination of planning, preventative maintenance, and formal contingency operations. Early-stage planning should start with a review of roof conditions and a knowledge of the roof design, drainages, roof coverings, and snow load capacity.
Snow loads are measured in pounds per square foot and are generally adopted by local governments. In Anchorage, for example, municipal codes regarding snow loads have been adopted from international residential and building standards and modified for local, seasonal snow loads. This dates to the ‘70s. The minimum required snow load capacity in Anchorage is 40 pounds per square foot.
By comparison, the requirement in the Fairbanks North Star Borough is 50 pounds per square foot, and in Juneau it is 70. This is a minimum required value regardless of the pitch or type of roofing. Some critical facilities or new facilities with flat roofs may be designed for higher loads.
It is important to know how a building was constructed and how much load it was designed for. One way to affirm these facts is to hire an engineer to inspect the building and calculate the load rating, regardless of the roof type.
Last year, a concern regarding a commercial roof design called a top chord hung roof truss was brought to light due to the snowy conditions. This design dates to the ‘70s and ‘80s, and the flaw in the engineering of this roof style is how the connection is made with the load-bearing wall and is subject to failure in which the wood splits. According to Municipality of Anchorage Engineering Services Manager Ross Noffsinger, “Once one truss fails, the load it was supporting now gets transferred to other trusses. They may pick it up and hold it for a while, but generally they’re the same type of truss. They can start to crack, and then eventually the whole thing can fail catastrophically.”
Multiple collapsed buildings in Southcentral Alaska experience this exact failure. These types of buildings should have an aggressive snow removal plan that includes frequent removal of accumulated ice and snow to prevent undue overloading of the building.
A schematic is another good idea, and combining these plans with a qualified contractor walk-through in advance of winter is even better. Snow removal companies should be selected based on reputation and quality of work, and they should provide a certificate of liability insurance with the building owner listed as an additional insured on the insurance policy. That way, if property damage caused by negligent work of the snow removal company does occur during snow removal, the claim is likely handled by that company’s insurance carrier.
Lastly, it is best to remove the snow in early February if December and January are snowy months. Waiting until later in the season when it becomes dire will cost more, as snow removal companies become busy and unavailable, and time becomes a factor as the stresses on the building continue to increase toward collapse.
In the wintertime, heat from the building as well as from melt-and-freeze cycles will create ice that can migrate under the influence of gravity. When the building does not drain correctly—which will likely cause ice dams on the edge of the building—the disproportionate loading can increase the probability of a collapse. Ice is much denser than snow, and one inch of ice is equivalent to roughly a foot of fresh snow. Therefore, keeping ice dams from forming is crucial. In any assessment, bear in mind that the overall calculation of the weight of snow on the roof should include all water, ice, and snow that is present.
It is impossible to know what the winter will bring for weather. This uncertainty can be managed by actively addressing concerns before larger problems arise, staying out front of property risks, and knowing that snow in Alaska is largely inevitable. The costs associated with proper roof maintenance, including snow removal, pale in comparison to a large property or liability claim.
Always remember that the workers, residents, and business invitees are relying on the property owners to ensure that the buildings are a place where people are safe. Providing a safe environment is not just a good business or investment strategy but will also help protect the most important resource that we have: human life. After all, risk never sleeps.
