Is bitumen to blame for the fire?

The fire at the Sky City Convention Centre is still burning this morning. Fletcher Building says it's still too early to confirm what caused the roof to catch fire. The fire was first spotted in an area where blowtorches were being used to seal bitumen roof joints. Graham Moor from the Roofing Association told reporter Charlotte Cook installing a bitumen roof shouldn't be dangerous, as long as you have good safety measures.