Beland, Dr. Bernard. Fire Places and Chimneys as Fire Causes. Fire and
Arson Investigator. March, 1983.
Abstract: This article discusses how insulation of the walls of
a chimney or fireplace could become a fire cause. Masonry brick in fireplaces
or chimneys acts as a natural insulator. The heat builds and eventually
the walls will reach equilibrium. This means that the heat has reached the
outside surface of the wall and will be dissipated into the air. If this
heat is not allowed to escape because of another source of insulation other
than the brick, the walls will reach very high temperatures, capable of
igniting surrounding combustibles.
An airspace is required by chimney codes to prevent this build-up of
heat. The standard requirement for a chimney is four inches of brick with
two inches of airspace. The back of a fireplace is usually required to be
eight inches thick with four inches of airspace. This airspace is the area
between the masonry brick and combustible materials. This allows the heat
to escape. When combustible materials are located near chimneys, insulation
should not be used.
For more information, contact:
International Association of Arson Investigators (IAAI)
300 Broadway Suite 100
St. Louis, MO 63102-2808