Jim Hoffman Theorizes...

And shows why theorizing is so discredited in the 9-11 Troof Movement:



Yep, explosive ceiling tiles. Now in fairness, he does note that these are not exactly something you can pick up at Home Depot:

All of the equipment is available off-the-shelf from commercial vendors or special operations supply depots except for the wireless explosive ceiling tiles, which have to be specially manufactured.

And Hoffman has figured out the time problem as well:

With workers swapping in new tiles at an average rate of two tiles per minute per worker, it takes a team of fourty workers 187 hours to retrofit an entire Tower. The work is performed in three weeks and weekends of night shifts, emptying one truckload per night, with the truck parking inconspicuously in the WTC subterranean parking garage.

Sounds completely credible to me. Then again, I am still waiting for that inheritance from my uncle who died in the plane crash that the nice bank manager told me about.