Baird, David J. Factory-built Chimney Chase Fires: A case For More Detailed Inspection. Building Standards. March/April, 1991.

Abstract: This article investigates a string of fires in California that have been attributed to chimney chases with attached decorative metal sheet shrouds. Because of their popularity, many types of untested metal shrouds have made their way to the marketplace.

Most manufactured factory-built fireplaces include instructions on building a chase flashing; however, none provide specifications for attaching anything to the top of them. According to the Uniform Mechanical Code, it is a violation to build a chase flashing without completely following the manufacturers instructions.

The investigations of the California fires determined that the installed decorative metal sheets heated and ignited surrounding combustibles. The article lists and describes the four types of metal sheet shrouds that are commonly attached to chimney flashings for decoration. These present a serious fire hazard because the factory-built chimneys cannot support additional unlisted attachments.