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.

Unfortunately, the industry puts out some terrible guidance:

  • An example from a large commercial insurance company (from the industry that bears the brunt of the risk) offers a checklist (PDF) ... of sorts. You'd think if they wanted roofers to use this they'd make it a little more friendly.
  • OSHA rolls the whole thing up with general job-site fire prevention (PDF) and the result is worse.
  • The Canadians have done a thorough job (PDF), but it still leaves a lot to be desired.
  • The San Francisco Fire Department includes a couple pictures but there guidance comes down to a city requirement for a “firewatch” on all jobs--a person who does nothing but watch the person doing the torch work to be sure that they are working safely.

Really, the best guidance seems to be coming from roofers talking to other roofers.