I am not a Nevada resident,don't know what building code is in effect but believe that regardless (IBC) whould require same as UBC in that 'parapets,mansards are to be constructed of same materials as walls'...'A,B occupancies over 4 stories are to be Type I, Type II Construction'

So why is it that on TV the fire and partricularly the falling burning debris gave the appearance of being some sort of organic substance such as tar paper,polyethyene,or at least a highly flamable material which was resisting extinguishment by mere water dousing ?

Last time I checked steel or concrete was not very flamable !