Building 7

Debris from the North Tower started fires on the lower floors. The water supply for the sprinklers there came from city mains broken by the tower collapses. NIST found that heat from the uncontrolled fires made floor beams on the east side expand, pushing a girder on Floor 13 off its seat at Column 79. Floors fell onto those below, Column 79 buckled, and the failure spread across the building. [1][2]

NIST called WTC 7 “the first known instance of a tall building brought down primarily by uncontrolled fires,” and said its fires were similar to those in other tall buildings where sprinklers did not work. It added that the debris damage did not start the collapse; the fires did. [2]

NIST considered and rejected a blast. It calculated that the smallest charge able to cut the critical column would have produced 130 to 140 decibels half a mile away; no such sound is on any recording, and no witness reported one. It also rejected diesel fuel stored in the building as a cause. [2]

From 2015 to 2019 a team led by Leroy Hulsey at the University of Alaska Fairbanks modeled the building. Its March 2020 report concluded that fire did not cause the collapse, that NIST’s girder walk-off could not have happened as described, and that the collapse was a near-simultaneous failure of every column. The project budget was $316,153, paid by Architects & Engineers for 9/11 Truth. [1]

The team published all its input and output files, more than 250 gigabytes. NIST, by contrast, withheld some of its connection models on the ground that they could be used to plan the destruction of similar buildings; a federal court upheld that in 2011. [1][2]

The study did not identify what did destroy the building and found no physical evidence of explosives. Its critics note its funding and that it set out to test a single alternative; its supporters say NIST’s refusal to release everything makes independent checks harder.

Two city officials were among the last people inside WTC 7: Barry Jennings and Michael Hess, Mayor Giuliani’s chief lawyer. NIST’s account is that they went up to the emergency management center on the 23rd floor, found it empty, and started down the stairs when the elevators failed as the South Tower fell. At the 6th floor the North Tower collapsed: the lights went out, the stairwell filled with smoke and debris, and they climbed back to the 8th floor, broke two windows and called for help. Firefighters brought them out. [1]

On 9/11 Hess told a reporter he had walked down to “the eighth floor where there was an explosion.” Jennings said he heard explosions, and in an interview for the makers of the film Loose Change he described stepping over people on the way out. To many people that is the strongest eyewitness evidence of demolition. [2][3]

In 2008 Jennings told the BBC: “I said it felt like I was stepping over them but I never saw any,” and that he had asked the filmmakers to pull his interview. The film’s director, Dylan Avery, said nothing was taken out of context. The BBC also found Hess, who said in his first interview since 9/11 that the lights went out and the building shook like an earthquake, and that he was now certain he had not heard an explosion. He had assumed one on the day. [2][3]

The dispute is about timing. If the blast came before the North Tower fell, it is hard to explain; if it was the tower falling onto WTC 7, it is what NIST describes. NIST found the North Tower severed seven columns on the building’s southwest side. Its lead investigator told the BBC the damage “really caused noises that were incredibly loud.” [1][3]