Metal Chimney Safety Alert - CPSC Document #5047 InspectAPedia® -
Common causes of fires at woodstoves
Safety warnings about chimney fires & Metal Flues
US CPSC Safety Alert Document # 5047
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Woodstove or fireplace insert safety includes making sure that your metal chimney or "flue" is safe. The US CPSC offers some succinct advice to avoid
having a costly and dangerous house fire or an unsafe gas leak hazard.
Consumer Product Safety Commission
Metal Chimneys: Safety Alert
CPSC Document #5047. For a succinct pamphlet on chimney and woodstove safety see this Chimney and Woodstove Fire Safety Code Information Sheet from Vermont.
[Before using your
wood stove, coal stove in the coming or current heating season] the US Consumer Product Safety Commission [since 1983 has] strongly urged you,
if you have a [wood stove or coal stove] or fireplace connected to a metal chimney, to check for any damage that may have occurred in the past heating season. Look
for signs of structural failure, such as deformation, cracks, or holes. If it is difficult to examine the chimney, a
local chimney repairman, chimney "sweep", or dealer can help. Have any damage repaired NOW.
Most fires in metal factory- built chimneys occur because of improper installation, use or maintenance. The Commission
staff has identified the following common causes:
Improper chimney installation causing ignition of nearby wood framing.
Structural damage to the chimney caused by burning creosote (a black tar-like substance which builds up inside the
Chimney corrosion resulting in wood framing being exposed to excessive temperatures.
Buckling and collapsing of the inner liner of the chimney. (This can result from too hot a fire, especially in
high-efficiency stoves and in fireplace inserts, or from a creosote fire.)
Many serious fires also occur in masonry chimneys, usually from improper installation or when the tile inner liner and
the surrounding brick or block structure crack and separate. Such cracks may be caused by the ignition of creosote.
Smoke and heat can then escape and ignite material near the chimney.
Even when the heating appliance is properly installed, people with both metal and masonry chimney systems should
frequently check the chimney for creosote deposits, soot build-up or physical damage. This involves only a simple visual
examination, but it should be done as often as twice a month during heavy use.
If you see heavy creosote build-up,
suspect a problem, or have had a chimney fire, a qualified chimney repairman or chimney "sweep" should perform a complete
safety inspection. They can arrange for any necessary repairs or creosote removal, which must be done before the heating
appliance is used again.
The US Consumer Product Safety Commission advises owners of these chimneys to:
Be sure that the chimney and stove pipe were installed correctly in accordance with the manufacturers' recommendations
and local building codes. If there is any doubt, a building inspector or fireman can determine whether the system is
properly installed.
Have the chimney checked routinely by a chimney "sweep" at least once a year, and more frequently if a stove is heavily
used (for example, if it's used as a primary heat source for the home).
Always operate your appliance within the manufacturers' recommended temperature limits. Too low a temperature increases
creosote build-up and too high a temperature may lead to a fire. Chimney temperature monitors are available and should
be used.
If you have had a fire or other safety problem with your chimney, please provide this information to the Commission by
calling the Commission's toll-free Hotline 800-638-CPSC.
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