I heard, from the early reports about the incident, that the "lack" of insulation, (some sort of asbestos type product that is sprayed onto the metal framework), which usually covers the metal substructure of most modern buildings, was a contributing factor to the collapse. According to the report, the WTC buildings did not have this insulation present. I don't understand why the builders were not required to do this. Was it a money issue or? I'm not trying to say that this coating on the metal would have changed the ultimate outcome of what happened that day. As to how much it may have helped, I'd leave that determination to the experts. Certainly if the building's frame would have been covered, the effects of the heat might have been lessened, at least allowing more time for rescue operations to take place.

When I first heard this report I was dismayed. I don't think this point has been brought to the forefront in the investigation as to why the buildings fell. There are certainly more important things to do at this time.