Debunking 9/11 truther Claims

I heard this “new” claim from a 9/11 guy I was arguing with online, that

“The problem is that the distortion part of that claim was proven to be overstated (again by the official tests) and the fire was never proven to be hot enough over a large enough area simultaneously for the weakening pat to be true.”

What do you think? I’m suspicious, of course. Since I’m not familiar with all the data and research (those NIST reports are very long), I’d like to find out what’s going on with this one. Where should I look to find evidence/data relevant for examining/refute this claim?