You bet that stuff is flammable...Just look at what happened in Atlantic City a few months back.
The cladding of a new 40 story casino tower at the Borgata caught fire on the ground floor. The blaze toasted the building ground to roof within minutes. Luckily it was still under construction at the time.
Pics below are from AC11 and can be found by following the below link...the pics are in the middle of the page:
http://forum.skyscraperpage.com/show...t=89260&page=5
again though...it was only superficial damage.