Chimneys: Safety Alert
Consumer Product Safety Commission
Chimneys: Safety Alert
CPSC Document #5017
In 1982, wood-burning appliances accounted for more fires,
more fire deaths, and greater property damage than any other kind
of heating fuel -- about 140,000 fires, 250 deaths and $257
million in property damage. These losses represented 20 percent
of all residential fires in the U.S., 5 percent of all fire
deaths, and 8 percent of estimated property damage.
CPSC research indicates that most wood heating fires involve
the chimney and not the appliance itself. The majority of these
fires are contained within the chimney and cause no damage to the
house. The Commission is concerned, however, not only about the
chimney fires that did ignite other parts of the house, but also
about the potential future hazard from the continued use of
chimneys whose structural integrity has been compromised by a
chimney fire. This is especially true in light of the fact that
many contained chimney fires are not reported to the fire
services; in fact, consumers may not even be aware that a chimney
fire has occurred.
Therefore, the Consumer Product Safety Commission is issuing
a special safety alert concerning chimneys used with woodburning
stoves, fireplaces, and fireplace inserts. The Commission
urgently warns consumers to be aware of the potential fire
hazards associated with these chimneys.
Now that the nation has entered the heating season, the
Commission strongly urges you, if you have a stove or fireplace,
to check the chimney for any damage that may have occurred in the
past heating season. 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 involving either masonry or prefabricated metal
chimneys occur because of improper installation, use or
maintenance. The Commission staff has identified the following
common causes of fires:
- Improper chimney installation too close to wood framing.
- Installation of thermal insulation too close to the chimney.
- Improperly passing the stovepipe or chimney through a ceiling
or wall, causing ignition of wood framing.
- Structural damage to the chimney caused by the ignition of
creosote (a black tar-like substance that builds up inside the
chimney in normal use).
Structural damage to metal prefabricated chimneys that
results in wood framing being exposed to excessive temperatures
or leakage of potentially toxic gases to the interior of the home
can take the following forms:
- Corrosion or rusting of the inner liners of metal chimneys.
- Buckling, separation of the seam, or collapsing of the inner
liner of metal chimneys. (This can result from too hot a fire,
especially in high-efficiency stoves and in fireplace inserts, or
from a creosote fire.)
Structural damage also occurs in masonry chimneys, often
associated with deterioration or improper installation of the
chimney. The tile inner liner and the surrounding brick or block
structure may crack and separate, perhaps as a result of the
ignition of creosote that has built up in the chimney. Many old
chimneys do not have a tile liner. If your chimney does not have
a liner, the addition of a properly installed liner is advisable.
Also, a clay liner should be sealed with refractory cement.
Even when the heating appliance is properly installed,
people with either metal or 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 buildup, 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.
There are products now available which, according to recent
tests conducted by independent laboratories, show promise for
reducing the production of creosote and harmful pollutant
emissions. Advance wood stove designs appear to provide more
complete combustion of the fuel. Catalytic combustors appear to
achieve similar results, and are available with new stoves or as
separate components which can be installed between the flue gas
exit and the chimney connector of existing stoves.
The Commission advises owners of all chimneys to:
- Be sure that the chimney and stovepipe were installed correctly
in accordance with the manufacturer's recommendations and local
codes. If there is any doubt, a building inspector or fire
official can determine whether the system is properly installed.
- Minimize creosote formation by using proper stove size and
avoiding using low damper settings for extended periods of time.
- Have the chimney checked and cleaned routinely by a chimney
"sweep" at least once a year. Inspect it frequently, as often as
twice a month if necessary, and clean when a creosote buildup is
noted.
- Always operate your appliance within the manufacturer's
recommended temperature limits. Too low a temperature increases
creosote buildup, and too high a temperature may eventually cause
damage to the chimney and result in a fire.
- Frequently look for signs of structural failure.
If you have had a fire or other safety problem with your
chimney, or would like additional information, call the
Commission's toll-free Hotline 800-638-CPSC.
008412