That was a pretty horrible fire. That said, there are chemicals that you can mix with the plastic as your making bricks that will make them self extinguishing

That was a pretty horrible fire. That said, there are chemicals that you can mix with the plastic as your making bricks that will make them self extinguishing (and its fairly important that they are, otherwise you get the "pile of recycled tires on fire" problem.) The chemicals can change the plastic's tensile strength (but leave the compression strength alone) so they generally not included in sheets like building cladding. Self extinguishing plastics were made popular by Dow Chemical in the late 60's.