Forensic Weather Analysis Evaluates Snow Load in Tennessee Hotel Roof Collapse
AccuWeather forensic meteorologists provided expert insight after a roof collapse
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Bong Wang uses a snow rake to try and clean an ice jam from the roof of his home, Saturday Jan. 9, 2010, in Omaha, Neb. (AP Photo/Dave Weaver)
Executive Summary
After a partial roof collapse at a hotel in Dickson, Tennessee, AccuWeather Forensics Services was asked to determine whether accumulated snow contributed to the failure of the roof trusses. AccuWeather’s expert forensic meteorologists analyzed snowfall, liquid content, snow weight, wind direction, and the hotel’s stepped roof design. Although wind-driven drifting increased the snow load on the lower section where the trusses failed, the analysis concluded that the accumulated weight was very unlikely to have reached the minimum snow-load requirement established by the building code in effect at the time of construction.
Key Takeaways
-- The partial roof collapse occurred on January 16, 2022.
-- AccuWeather analyzed weather conditions from January 1 through January 16, 2022.
-- Meteorologists calculated snow weight using its liquid content, with one inch of liquid equivalent weighing approximately 5.2 pounds per square foot.
-- Three snowfall events contributed varying amounts of snow to the hotel roof.
-- The stepped roof design and wind direction allowed snow to drift from the higher roof onto the lower section.
-- The roof truss failures occurred in the lower, downwind portion where drifting increased the snow load.
-- AccuWeather determined that the snow load was very unlikely to have reached the building code minimum of 16 pounds per square foot.
Investigating a Hotel Roof Collapse in Dickson, Tennessee
On January 16, 2022, a partial roof collapse occurred at a hotel in Dickson. The immediate structural cause was identified as the failure of roof trusses. AccuWeather was retained to evaluate the weight of snow on the roof and determine whether that load could have contributed to the damage.
Calculating Snow Weight From Historical Weather Data
AccuWeather’s forensic meteorologists reviewed historical weather data covering January 1 through January 16. Because the weight of snow varies according to its liquid content, the investigation examined more than snowfall depth alone. One inch of liquid water contained in snow weighs approximately 5.2 pounds per square foot, providing a basis for calculating the load placed on the roof.
The analysis found that light snowfall on January 2 produced a load of slightly more than one pound per square foot. Snowfall on January 6 added approximately 2 to 3 pounds per square foot, while the January 16 snowfall had an average weight of approximately 1.3 pounds per square foot. Individually, these loads were too small to be expected to damage a properly designed building.
How Wind and Roof Design Affected Snow Accumulation
The hotel’s stepped roof created conditions that allowed drifting to occur. During the three snowfall events, the wind carried some snow from the higher section of the roof toward the lower section. The higher roof step blocked the wind, allowing a deeper drift to build on the lower, downwind portion of the structure.
As a result, the lower roof carried more snow than the average load calculated across the property. This localized accumulation was important because the roof truss failures occurred in the same lower, downwind area.
AccuWeather’s Findings on the Roof Snow Load
Although drifting increased the snow load near the failed trusses, AccuWeather determined that it was very unlikely for the accumulated snow to have reached 16 pounds per square foot. That figure represented the minimum building code requirement in effect when the hotel was constructed. The analysis provided scientifically supported evidence for evaluating whether weather conditions or other factors were responsible for the structural failure.
Expert Forensic Meteorology for Property Damage Cases
AccuWeather’s forensics meteorologists analyze historical weather conditions, snow loads, wind patterns, rainfall, ice formation, and other environmental factors in property damage and construction-related disputes. The team includes Certified Consulting Meteorologists with extensive experience preparing defensible reports, explaining complex findings, providing depositions and testimony, and responding to cross-examination.
By combining multiple weather datasets with a collaborative review process, AccuWeather helps attorneys, insurers, engineers, and property owners understand how weather affected a specific location. Clear analysis and credible expert testimony can help distinguish between weather-related damage and failures involving structural design, construction, maintenance, or other causes.
Why attorneys and insurers use AccuWeather Forensics
-- AccuWeather’s expert forensic meteorologists have extensive experience in the courtroom, provide articulate explanations of the situations and are experienced and credible handling cross examinations.
-- AccuWeather has more than 1% of the world’s 235 active Certified Consulting Meteorologists (CCMs) — a distinction that builds trust and supports more favorable outcomes in legal cases. Each CCM has more than 40 years of experience.
-- AccuWeather’s expert forensic meteorologists collaborate to deliver consistent, defensible determinations for all weather events and weather parameters, providing expert testimony valued for their accuracy, credibility and clarity in court, helping attorneys in achieving the best outcomes.
-- AccuWeather’s trusted reputation and recognition adds validity to expert testimony and enhances the credibility of all reports submitted. In cases where weather is a key factor, the strength of the AccuWeather brand can positively influence how evidence is received by jurors.
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