fires occur when deposits of carbon and dust accumulate in
a chimney and are set alight by sparks or flames from an open
fire. The deposits result when wood burns slowly and produces
smoke, the smoke condenses on the cool inner surface of the
chimney and a layer of creosote forms. Creosote is a highly
flammable material. If it ignites at the base of the chimney,
it can produce a raging fire that travels up the chimney at
extremely high temperatures. Most solid fuels create some kind
of soot which without regular cleaning of chimneys builds up
in the flue and eventually catches fire.
How Are Chimney Fires Avoided?
Regular cleaning is the only way chimney fires can by avoided.
The National Safety Council recommends that chimneys be swept
thoroughly at least twice a year, once perhaps at the beginning
of the cold weather period, i.e. after the summer/autumn, to
clear the chimney of debris (birds’ nests, etc.) which
may have accumulated and also to remove soot. They should also
be swept mid-way through the winter to ensure a fire does not
occur. Obviously the more often a fire is lighted and the more
varied the fuels used, the more frequently it should be cleaned.
Do not rely on chemical blocks, etc., to clean a chimney. There
is no better method than a sweep’s brush!
Are They Dangerous?
Yes, chimney fires are particularly dangerous in that they
can structurally weaken the flue liner and chimney block causing
cracks to form into which sparks may enter and so breed fires
elsewhere in the house. Burning soot may also fall on carpets
etc. and set them alight.
What To Do If a Fire Starts?
- Close the glass doors and air inlets
- Get everyone out of the house, including yourself
- Call the fire department
- Use a garden hose to spray down the roof (not the chimney)
so the fire won't spread
Why Do I Need a Chimney Inspection?
“A chimney inspection is like an annual dental check-up," states
Ashley Eldridge, director of education at the Chimney Safety
Institute of America (CSIA). "It's preventative maintenance
that helps minimize potential hazards. Sometimes, maintenance
requires extra diligence."
To reduce the risk of chimney fires, the CSIA cautions people
that might be increasing their fireplace use in the fall and
winter to put a chimney inspection at the top of their home
improvement list. This caution is primarily directed at people
who might increase their wood-burning fireplace usage from
an occasional fire to a weekly activity. According to Eldridge,
people who use fireplaces infrequently tend to be less informed
about the important role that the chimney plays in exhausting
the hot gases and smoke from a fire. When a chimney has creosote
build-up, or is obstructed by a bird's nest or debris, it has
the potential to catch fire and cause damage.
According to the U.S. Consumer Product Safety Commission there
were 18,300 residential fires in the United States in 1998
originating in chimneys, fireplaces and solid fuel appliances.
These fires resulted in 160 personal injuries, 40 deaths and
$158.2 million in property damage.
Tips for Reducing the Threat of a Chimney
- Add a chimney cap to the top of your chimney. A cap can
keep out damaging moisture, which wears away masonry and
other metal components within a chimney.
- Ensure that your chimney has an appropriate liner. Chimney
liners are required in new construction to separate system
emissions from the structure of your home.
- Have chimney flashing (the seal between the chimney and
the roof) inspected and maintained. Flashing prevents rain
water and snow melt from entering a house and causing costly
damage to walls and ceilings.
- The National Fire Protection Association (NFPA) also recommends
that all chimneys be inspected on an annual basis to prevent
Reprinted with permission from the Chimney
Safety Institute of America, www.csia.org