Link
That article makes a thorough hash of the controlled explosion theories and points out some of the reasons why the towers collapsed the way they did.
Jowenko might be in the explosives and demolitions business, but he is not infallible and since he seems to be the ONLY source the 911 Truther movement uses for their claims of controlled demolition, his testimony is suspect at best. The problem with trying to find anything other than Truther bull**** is considerable, because almost everything that comes up is conspiracy theories.