Authorities say a roofing crew left the scene after a Chicago-area strip mall burned. The crew left their propane tanks, which exploded shortly after the fire erupted. Police hunting for the roofers are treating it as a criminal investigation.
A fire department video of the fire 10 minutes after the alarm shows how quickly the fire overtook the building. Torch-down roofing remains a popular material because it performs well and is easy to install. In its molten state, modified bitumen bonds tightly to metal flashing, and the rubbery additives in the asphalt allow the roofing to expand and contract with changes in temperature, where other roofing systems tend to crack. But while torch-down roofing is not difficult to install, the use of an open flame to melt the material can be dangerous. Roofers not only need training but a crew can't skimp on safety when applying it.