When the building was renovated, the materials used for the outside of the building were changed. Fire safety experts have speculated that this new material was a possible cause of the rapid spread of the fire. They said it essentially worked like a chimney in spreading the fire. The material could be seen burning and melting, causing additional speculation that it was not fire resistant. One resident said, "The whole one side of the building was on fire. The cladding went up like a matchstick."