NIST WTC 7 Investigation Finds Building Fires Caused Collapse


NIST WTC 7 Investigation Finds Building Fires Caused Collapse
Report and Recommendations for Improving Building Safety Released for Comment

August 21, 2008

(301) 975-3097

Michael Newman , NIST
(301) 975-3025

GAITHERSBURG, Md.—The fall of the 47-story World Trade Center building 7 (WTC 7) in New York City late in the afternoon of Sept. 11, 2001, was primarily due to fires, the Commerce Department’s National Institute of Standards and Technology (NIST) announced today following an extensive, three-year scientific and technical building and fire safety investigation. This was the first known instance of fire causing the total collapse of a tall building, the agency stated as it released for public comment its WTC investigation report and 13 recommendations for improving building and fire safety.

“Our study found that the fires in WTC 7, which were uncontrolled but otherwise similar to fires experienced in other tall buildings, caused an extraordinary event,” said NIST WTC Lead Investigator Shyam Sunder. “Heating of floor beams and girders caused a critical support column to fail, initiating a fire-induced progressive collapse that brought the building down.”

“Video and photographic evidence combined with detailed computer simulations show that neither explosives nor fuel oil fires played a role in the collapse of WTC 7,” Sunder said. The NIST investigation team also determined that other elements of the building’s construction—namely trusses, girders and cantilever overhangs that were used to transfer loads from the building superstructure to the columns of the electric substation (over which WTC 7 was constructed) and foundation below—did not play a significant role in the collapse.

According to the report, a key factor leading to the eventual collapse of WTC 7 was thermal expansion of long-span floor systems at temperatures “hundreds of degrees below those typically considered in current practice for fire resistance ratings." WTC 7 used a structural system design in widespread use.

Citing its one new recommendation (the other 12 are reiterated from the previously completed investigation of the World Trade Center towers, WTC 1 and 2), the NIST investigation team said that “while the partial or total collapse of a tall building due to fires is a rare event, we strongly urge building owners, operators and designers to evaluate buildings to ensure the adequate fire performance of the structural system. Of particular concern are the effects of thermal expansion in buildings with one or more of the following features: long-span floor systems, connections not designed for thermal effects, asymmetric floor framing and/or composite floor systems.” Engineers, the team said, should be able to design cost-effective fixes to address any areas of concern identified by such evaluations.

The investigators also reported that if the city water main had not been cut by the collapse of World Trade Center towers 1 and 2 (WTC 1 and WTC 2), operating sprinklers in WTC 7 would likely have prevented its collapse. “Nevertheless,” Sunder said, “we recommend that building standards and codes be strengthened beyond their current intent to achieve life safety by preventing structural collapse even during severe fires like this one, when sprinklers do not function, do not exist or are overwhelmed by fire.”

Sunder identified several existing, emerging or even anticipated capabilities that could have helped prevent WTC 7’s collapse. He cautioned that the degree to which these capabilities improve performance remains to be evaluated. Possible options for developing cost-effective fixes include:

  • More robust connections and framing systems to better resist effects of thermal expansion on the structural system.

  • Structural systems expressly designed to prevent progressive collapse, which is the spread of local damage from a single initiating event, from element to element, eventually resulting in the collapse of an entire structure or a disproportionately large part of it. Current model building codes do not require that buildings be designed to resist progressive collapse.

  • Better thermal insulation (i.e., reduced conductivity and/or increased thickness) to limit heating of structural steel and to minimize both thermal expansion and weakening effects. Insulation has been used to protect steel strength, but it could be used to maintain a lower temperature in the steel framing to limit thermal expansion.

  • Improved compartmentation in tenant areas to limit the spread of fires.

  • Thermally resistant window assemblies to limit breakage, reduce air supply and retard fire growth.

The 12 recommendations reiterated from the WTC towers investigation address several areas, including specific improvements to building standards, codes and practices; changes to, or the establishment of, evacuation and emergency response procedures; and research and other appropriate actions needed to help prevent future building failures.

Determining the probable collapse sequence for WTC 7, NIST found that the impact of debris from the collapse of WTC 1 ignited fires on at least 10 floors of WTC 7, and the fires burned out of control on six lower floors. The heat from these uncontrolled fires caused thermal expansion of the steel beams on the lower floors of the east side of WTC 7, damaging the floor framing on multiple floors. Eventually, a girder on Floor 13 lost its connection to a critical interior column that provided support for the long floor spans on the east side of the building. The displaced girder and other local fire-induced damage caused Floor 13 to collapse, beginning a cascade of floor failures down to the fifth floor. Many of these floors had already been at least partially weakened by the fires in the vicinity of the critical column. This collapse of floors left the critical column unsupported over nine stories.

“When this critical column buckled due to lack of floor supports, it was the first domino in the chain,” Sunder explained. “What followed in rapid succession was a progression of structural failures. Failure first occurred all the way to the roof line—involving all three interior columns on the most eastern side of the building. Then, progressing from east to west across WTC 7, all of the columns in the core of the building failed. Finally, the entire façade collapsed.”

Diagram 1—Typical WTC 7 floor showing locations of columns (numbered). The buckling of Column 79 was the initiating event that led to the collapse of WTC 7. The buckling resulted from fire-induced damage to floors around Column 79, failure of the girder between Columns 44 and 79, and cascading floor failures. [Download high-res version]

The investigation team considered the possibility of other factors playing a role in the collapse of WTC 7, including the possible use of explosives, fires fed by the fuel supply tanks in and under the building, and damage from the falling debris of WTC 1.

The team said that the smallest blast event capable of crippling the critical column would have produced a “sound level of 130 to 140 decibels at a distance of half a mile,” yet no noise this loud was reported by witnesses or recorded on videos.

As for fuel fires, the team found that they could not have been sustained long enough, could not have generated sufficient heat to fail a critical column, and/or would have produced “large amounts of visible smoke” from Floors 5 and 6, which was not observed.

Finally, the report notes that “while debris impact from the collapse of WTC 1 initiated fires in WTC 7, the resulting structural damage had little effect in causing the collapse of WTC 7.”

The investigation team found that the design of WTC 7 was generally consistent with the New York City building code in effect at the time. The estimated 4,000 occupants of WTC 7 on the morning of Sept. 11 were evacuated without any fatalities or serious injuries.

To reach the conclusions in its report, NIST complemented its in-house expertise with private-sector technical experts; accumulated an extensive collection of documents, photographs and videos related to the WTC events of 9/11; conducted first-person interviews of WTC 7 occupants and emergency responders; analyzed the evacuation and emergency response operations in and around WTC 7; and performed the most complex computer simulations ever conducted to model a building’s response behavior and determine its collapse sequence due to a combination of debris impact damage, fires and a progression of structural failures from local fire-induced damage to collapse initiation, and, ultimately, to global collapse.

NIST welcomes comments on the draft report and recommendations—available online at—received by noon Eastern Daylight Time on Sept.15, 2008. Comments (instructions for submission are available at may be submitted via:

  • e-mail to;
  • fax to (301) 869-6275; or
  • surface mail to WTC Technical Information Repository, Attn: Stephen Cauffman, NIST, 100 Bureau Dr., Stop 8611, Gaithersburg, Md. 20899-8610.

The NIST investigation of WTC 7 was conducted under the National Construction Safety Team (NCST) Act, as part of its overall building and fire safety investigation of the World Trade Center disaster. The act gives NIST the responsibility for conducting fact-finding investigations of building failures that resulted in substantial loss of life or that posed significant potential of substantial loss of life. NIST has no regulatory authority under the NCST Act.

As an agency of the U.S. Department of Commerce, NIST promotes U.S. innovation and industrial competitiveness by advancing measurement science, standards and technology in ways that enhance economic security and improve our quality of life.

Richard and AE911Truth's

Richard and AE911Truth's conference call just started. You can listen to it at


The Tele-Conference Dial-in # for listeners is (712) 432-1001
and the access code is: 442-618-649#

A healthy dose of reality instead of nonsense.

Well no suprise here....

I could have predicted the conclusion of this report and I have 0 engineering knowledge. I missed the broadcast so I'm wondering how did they explain

1. The piece of evaporated steel that was the "biggest mystery of all"?
2. The speed of the collapse?
3. The huge clap of thunder heard?
4. The various reports of explosions going off prior to collapse?
5. The firefighters fighting WTC 5 or 6 while 7 stands smokin'?
6. The lack of steel tested for explosives?
7. The symmetrical collapse from asymmetrical fires?
8. The outsourced conditions of the study limiting the research to the 7th floor and up?

NIST= No Interest in Science,Thank you!

I hope Scholars and AE release a press release to the MSM and other sources depicting the utter failure of this study.

"I would imagine that if you took the top expert in that type of work and gave him the assignment of bringing these buildings down with explosives, I would bet that he could do it." -1993-John Skilling, Head Structural Engineer WTC Towers


NIST= No Interest in Science,Thank you

I like that!

What about FEMA?

FigurE out how to MAke up stories about disappearing storeys?

Anyone something better?


No Interest In Seeking Truth

No Interest in Seeking Truth!

Thank you, peacefulwarrior. It's a perfect summary to the NIST, ahem, "investigation", "No Interest in Seeking Truth."

...don't believe him!


was able to watch the presentation on just a few minutes ago. now the link is GONE!
i can't watch it again. now it says that the presentation will be available tomorrow, 22nd of august.

anyone experienced something similar?

oh, as usual, NIST it talking shi*. anyone seen the animations? how the hell do they expect us
to take those animations seriously when they do not depict what videos depict?

"wtf i hate all cops"

Interesting how NIST "proves" this

with computer simulation when they simply could study the actual steel.
Why didn't they ? That would not have taken so many years to analyse..

I don't think

they had any of the original steel. It was shipped off to be recycled in China.

How is that possible?

This steel was invaluable in solving the mystery of this unique collapse!

More information regarding the steel...

and how it was illegally disposed of...

at :


This NIST presentation has got me fuming, nothing short of TREASON !!!

Best wishes

Not according to mayor Michael Bloomberg

who said you don't need the steel because "these days it can all be done with computer models."

And, of course, that's what NIST did.


........after seven years , this is the best they can come up with? I think i am going to start a demolition company. All i would need is a few five gallon gas cans.
What an insult to any American with common sence. I sure hope Gage,Jones, Ryan jump on this line of BULLS**T !

Seems more like how a house of cards collapses than a modern

steel-framed building! The building is said to have basically hollowed itself out, and then it imploded. Preposterous!

"The team said that the smallest blast event capable of crippling the critical column would have produced a 'sound level of 130 to 140 decibels at a distance of half a mile, yet no noise this loud was reported by witnesses or recorded on videos'"

That in no way rules out the use of explosives and/or incendiaries like thermite/thermate!

Consider mass emailing truth messages. More info here:

What is the decibel level of the explosion...

... that can be heard in this video?

Surely it badly startles the first responders.

More half-truths

The team said that the smallest blast event capable of crippling the critical column would have produced a “sound level of 130 to 140 decibels at a distance of half a mile,” yet no noise this loud was reported by witnesses or recorded on videos.

Sure, with conventional explosives. But the issue over sound would likely not apply to any one of the many various forms of super thermite/thermate.

This is just one of several examples suggesting that NIST is setting up a safety net to bail itself out of any serious future WTC7 investigation. The Shyam Sunder team will simply say they only considered conventional energetic materials and not anything even remotely novel.

[EDIT: Guess Columbo spotted it first!]


What about the video of the fireman making a call on a pay phone when an explosion is heard, and the caller reacts, turning towards the sound? I'll look for the link.


NIST are lying... There were sounds of explosions !!!

If you watch Arie's excellent WTC7 short video... The Third Tower (YouTube)

You'll hear testimony from an eyewitness describing Claps of Thunder


A few more explosions heard during the day (could easily be pre-blast cutter charges) at :

and the best one (Turn your sound up nice and loud for NIST)

Link :


Best wishes to the scholars and researchers in smacking this anti-science provided by NIST.

I Have To Admit...

To someone like me, someone who doesn't know a floor truss from a cantilever overhang, NIST's explanation for the collapse of WTC7 sounds questionable at best. They admit that "this was the first known instance of fire causing the total collapse of a tall building," and that it was an "extraordinary event." Extraordinary like the most defended airspace in the entire world being left completely undefended 34 minutes after the entire world knew America was "under attack?" Extraordinary like the worst possible candidate being put in charge of the 9/11 Commission? Also, I'm waiting for the media to jump on NIST's explanation to declare the 9/11 Truth Movement dead, and so far, the media is staying away. Here is every news article I've been able to find:

8:15 a.m. - Report Due on 9/11 Building Collapse
Fed gov't finds fires took down building next to twin towers
Feds say fires downed building next to twin towers

Are they embarrassed by the explanation?

Without sounding confrontational, I still firmly believe that the issue of how those buildings came down does not define this movement.

Edit: This post was from early yesterday morning... since that time, the NYTimes, Popular Mechanics, and other "News" outlets have picked up the story.

Do these people deserve to know how and why their loved ones were murdered? Do we deserve to know how and why 9/11 happened?

In other news

Leprechauns responsible for price of gold.


The official title of this report should be:

Lies (And the Lying Liars Who Tell Them): A Fair and Balanced Investigation of the WTC 7 "collapse" by NIST

Time after time

The Shamasunder Hour (52 minutes)

Here are just a few points re: "thermal expansion" of NIST

NIST makes this statement upon which the (supposed) initiation of collapse began: "...the effects of thermal expansion in buildings with one or more of the following features: long-span floor systems, connections not designed for thermal effects, asymmetric floor framing and/or composite floor systems.”

Since steel is an excellent conductor of heat, heat will easily transfer along connected steel beams. Heat also tends to be distributed. Heat will attempt to disperse & dissipate. {Anyone can test this sometime by barehanded, picking up an iron skillet handle after the skillet has been on a hot stove top.}

The fact that steel transfers and distributes and dissipates heat makes huge pieces of steel (or interconnected steel) difficult to melt, soften, or distort. Tremendous quantities of thermal energy are required for huge steel members to suffer significant compromise.

Also, add to this fact that once the office material is burned-up, the temperature lowers because the fuel has been consumed. Thus, fires typically travel towards another source of fuel or eventually estinguish. With routine office fires, this infers that a focus of heat can not be applied towards a specific area for any long concentration of time. Using this tidbit of information about the reduction of the heat source, it would be ludicrous to think that a normal office fire would be sufficient to focus heat onto a region of a huge network of steel for any significant time.

Despite the ridiculous nature of NIST's findings...we all knew that they would be trying to cover up the fact of explosives. Some pretty evil, insidious traitors are on this NIST team.
Someday, I would love to see criminal and civil prosecution of those responsible for this outrageous cover-up. Any jury, hearing the evidence and seeing the devastation which has resulted from their treasonous acts, would side for the greatest punishments possible.

Column #79

collapses, and the penthouse falls first, and uniform. It also causes squibs to go shooting out the side from bottom to top.
A 6.6 second symetrical collapse because of fire! This is pure BULLSH**T !

So we have gone from

"the columns were melted", to "the columns were softened, to "the columns thermally expanded."

Each step requires lower temperature, so is closer to reality.

But it is outrageous to claim that a building collapsed due to its thermal expansion!

haha, the next step will be:

"The sound of the collapsing towers made the collumns vibrate so badly that they got scared" or "The sound made them so scared that they trembled and subsequently shattered in fear"

Same old tricks

On the basis of this press release, it appears that NIST is adopting the same strategy that they used in their WTC 1& 2 investigation. That is, they postulate a plausible (if unlikely) initial failure mechanism, and then wave their hands to suggest that is was sufficient first cause to generate the catastrophic and rapid collapse that ensues. This is sufficient for the uncritical minds that will tend to swallow this up.

I suspect that, like the WTC investigation, their computer analysis does not include any meaningful assessment of the mechanism of progressive failure following this initial first cause. In order to produce the type of collapse that was observed, the connections between ALL structural members must have failed instantaneously. However, in reality, once one connection fails, that connection ceases to act upon members that are farther along the load path. That force is no longer available to pull apart subsequent connections. As a result, the propagation of the failure wave throughout the building should be halted as soon as the first connection fails. Therefore, it is physically impossible for the failure to propagate through the building unless one postulates an external forcing mechanism applied distributively throughout the structure. This mechanism could be either explosive devices, or fairy magic. Which one is it, NIST?

No explosions heard?

From the AP..."Sunder said his team investigated the possibility that an explosion inside the building brought it down, but found there was no large boom or other noise that would have occurred with such a detonation."

oops...."We gotta get back...sevens exploded!".....

NIST also places Brooklyn Bridge up for sale.

Accepting offers on Ebay.

Interesting how Counterpunch's great authority Manuel Garcia (of Lawrence Livermore Laboratories) is completely dissed by this report. He put a lot of FAITH into the fuel stored in WTC7. Wonder how his faith is holding up?

This new report seems to put the nail in the coffin. They describe all sorts of ASYMMETRICAL DAMAGE, when clearly the building is brought down perfecly symmetrical, such that any professional demolition company would be proud to show that footage on their website, if they had done it via contract.

No explanation why all that UNDAMAGED STEEL also crumbled like dry twigs. Why did the building not topple in one large chunk, as numerous other steel framed collapses have done before? No explanation there, and there won't be.

Needless to say, thermate wasn't touched. No steel spherules, no molten steel beneath the rubble, no steel evidence remains at all! No calling out the felony of destroying crime scene evidence.

Quite a sham.

70 Disturbing Facts About 9/11

John Doraemi publishes Crimes of the State Blog

johndoraemi --at--

NIST site down?

Anyone else having trouble accessing ?

Where's the physical evidence of this fire?

Where are the beams and support columns that failed? Is this too much to ask?

Oh, and China is not an acceptable answer.


and has anybody seen ANY fire during the collapse?
I didn't !

How can a building collapse "due to fire" without a fire?

Especially when there is no sign

of any of the fires jumping floors or firewalls.

The smaller fires that were observed ran out of fuel and burnt themselves out.

If the firewalls held, then there's no way structural steel got hot enough to fail from fire.

... Back in reality

I like the part where all of the steel is "cut" into small and easily manageable pieces--you know, so that controlled demolition Inc. could help with the cleanup. Did I just say cleanup? I meant evidence disposal. Just a miraculously helpful coincidence of course.

Why is a controlled demolition company cleaning up small office fire calamities. It must have embarrassed their company, considering all the hard work it takes to demolish a building as perfectly as we saw on 9/11.

Molten steel? Nah, that's not significant or worth mentioning. Evidently, "no evidence" of explosives means just pretending that there was no molten steel.

"FEMA's volunteer investigators did manage to perform "limited metallurgical examination" of some of the steel before it was recycled. Their observations, including numerous micrographs, are recorded in Appendix C of the WTC Building Performance Study. Prior to the release of FEMA's report, a fire protection engineer and two science professors published a brief report in JOM disclosing some of this evidence. 1

The results of the examination are striking. They reveal a phenomenon never before observed in building fires: eutectic reactions, which caused "intergranular melting capable of turning a solid steel girder into Swiss cheese." The New York Times described this as "perhaps the deepest mystery uncovered in the investigation." 2 WPI provides a graphic summary of the phenomenon. "
A 9/11/2008 Resolution: Start Your Own 9/11 Blog

unlucky floor 13

Any average person knows you shouldn't build buildings with a 13th floor it's unlucky!

Wow it's amazing what you can do with computers these days eh?

My theory is it's the lone gunman in the book depository in Dallas who fired a shot that took about 40 years to reach building 7 and generate a new "War In" report.

Repeat Broadcast for both news conferences Thursday, August 21st --- 7:30pm Pacific - 10:30pm Eastern - 2:30 GMT

Repeat Broadcast for both news conferences Saturday, August 23rd --- 11am Pacific - 2pm Eastern - 18:00 GMT

Both will be archived here after the broadcasts.

If a tree falls in the forest, and nobody hears it, did it really fall? I once heard a giant redwood fall in Muir Valley, from the overlook above...I couldn't see it, but the thundering noise went on for at least 15 seconds, which is a long time...

So it would follow that since the building fell, there was noise, which in the panic and confusion, may have become unclear as to what noises were heard when. Detonation would first garner attention, then witnesses would turn to see the collapse already in progress.

20-minute fires

In December, NIST said that the fires died down in 20 minutes in any given location in the building.

"At any given location the combustibles needed about 20 minutes to be consumed."

Do they now explain how such short-lived office fires could have caused ANY steel to weaken in ANY way?

It seems that a narrow Finnish wooden plank is more fire-resistant than massive WTC steel:

Pure fantasy, as usual

Even a cursory glance at thing makes the report crumble even faster than WTC 7 itself.
It says it's a "final report," but even now, seven years after 9/11, it's still labelled a "draft for public comment."
First and foremost, to have us believe that the structure of the entire building depended on a single column ("no. 79") is simply ludicrous on its face. It deserves almost no comment.
Second, the pics and videos they use are doctored (whited out) to avoid showing the upward progression of explosions at the southwest corner of the building we have all seen a thousand times on the CBS video. If it doesn't exist, they don't have to explain it.
As others have mentioned, no mention of the intergranular melting, molten steel, no explanation of speed of collapse, its symmetricality, etc.
Worst of all, we will see the major media simply repeat the report's conclusions with no questions asked and disparage those of us who ask questions.

EMAIL Architects & Engineers with the website

Email every Architect and Engineer that you can find with the website. You can also attach the "Hard Evidence Letter" --> (or even mail it to them). {{I have emailed over 300 as of today. And I have mailed out more than 170 DVDs/info to firms.}}

Here is a source of architects --->
Your state has a source for engineers ---> and...

3 Minute Video

BELOW - The first 2 minutes tell the story.

Fire Alarms in "Test" mode from 6:47:03 a.m. on September 11, 20

Fire Alarms in "Test" mode from 6:47:03 a.m. on September 11, 2001. Part of the Miracle!

Was it just a coincidence that the WTC 7's fire alarm was placed on "TEST" mode at 6:47am on 9/11 which would have ignored any alarms that went off and would not be shown on the operator's display?

"Finding 2.25: The fire alarm system that was monitoring WTC 7 sent to the monitoring company only one signal (at 10:00:52 a.m. shortly after the collapse of WTC 2) indicating a fire condition in the building on September 11, 2001. This signal did not contain any specific information about the location of the fire within the building. From the alarm system monitor service view, the building had only one zone, “AREA 1.” The building fire alarm system was placed on TEST for a period of 8 h beginning at 6:47:03 a.m. on September 11, 2001. Ordinarily, this is requested when maintenance or other testing is being performed on the system, so that any alarms that are received from the system are considered the result of the maintenance or testing and are ignored. NIST was told by the monitoring company that for systems placed in the TEST condition, alarm signals are not shown on the operator’s display, but records of the alarm are recorded into the history file." - NIST: Progress Report - Chp 1; (PDF - pg 28) (June '04)

Active Fire Protection Systems—Fire Alarm Systems
Finding 2.25 pg 28

Fire Alarms in "Test" mode from 6:47:03 a.m. on September 11, 20

Who turned off the alarms and sprinklers?

Active Fire Protection Systems—Fire Alarm Systems
Finding 2.25 pg 28