"Our investigation found that the facility collapsed under a wind load that a building of this type should have been able to withstand," said John Gross, who led the agency's review.
As part of its report, the agency recommended that fabric-covered structures in general be evaluated for their ability to hold up under windy conditions. Besides serving as practice facilities for professional and college football teams, such buildings are widely used as casinos, warehouses and military facilities.
The collapse of the Cowboys' 88,000-square-foot structure left team scouting assistant Rich Behm paralyzed from the waist down and 11 others less severely injured. Behm and Cowboys special teams coach Joe DeCamillas, who suffered a broken vertebrae, are suing the building's manufacturer, Summit Structures LLC of Allentown, Pa., and others associated with the project.
Tom Fee, a Dallas attorney who is representing Summit in the lawsuit, issued a written statement reiterating the company's position that an unusual weather event contributed to the collapse.
"Summit values its Seventh Amendment right to a trial by jury and will present credible evidence of a catastrophic weather event in the appropriate forum and at the appropriate time," he wrote.
The statement also noted that the NIST report contained "a number" of incorrect assumptions and that there is information that isn't available to the agency.
Frank Branson, the attorney for Behm and DeCamillas, said the report confirms much of what his experts have already learned.
"This (document) basically says the building was so under-designed it folded like a $2 suitcase," he said.
Cowboys spokesman Rich Dalrymple said the team had no comment.
The building was erected in 2003 and modified with a new fabric covering and additional structural reinforcement in 2008.
The report by the agency, a non-regulatory arm of the Commerce Department, was the work of a team of structural engineers who visited the scene shortly after the accident and later constructed a model of the ruined building. A final report will be prepared after a four-week comment period.
Among the issues raised in the report is Summit Structure's "assumption" that the roof fabric could provide support for the frame.
"Of particular concern, fabric material is susceptible to tearing due to wind-born debris during storms," the report states.
Other contributing factors cited by the agency were incorrect calculations of the height and slope of the roof and the assumption that the building was fully enclosed when in fact it had vents and doors. Gross said his group thought the problems it discovered with the Cowboys' facility make it imperative that similar buildings be examined, possibly by independent inspectors.
"We certainly can't address how others were designed, constructed or used, but we found a sufficient number of issues with this one," he said.
The Cowboys' facility was at least the fifth designed by Summit known to have failed since 2002. The team hired the company just months after a warehouse it built for the Philadelphia Regional Port Authority collapsed in a snowstorm.
One of Summit's largest buildings is the football practice and indoor track facility at Texas A&M University. The university issued a statement Tuesday saying it has reinforced the cables supporting the structure's steel trusses as a result of an independent analysis requested by the school's interim president, R. Bowen Loftin, in August.