Chimney Fires
Chimney Fires
Construction, Challenges
Fire Control Best Practices
Objectives
• Review different types of chimney
construction
• Identifying lined vs. unlined flues
• Understand fire spread characteristics of
most common chimney types
• Effective fire control practices
Chimney Construction
• The chimney method of smoke
removal has been around for
centuries.
• All chimneys are essentially
manufactured in a similar fashion.
The by-products of the fire exit
upward by convection through the
chimney flue.
• Early man discovered the benefits
of vertical draft methods in
removing smoke from caves, huts,
etc.
Chimney Construction (cont.)
• Various means to
construct vertical
drafts (chimneys)
used:
–
–
–
–
–
Stone
Mud/sticks
Hollow logs
Bricks
Metal (modern)
Attachment Methods
•
•
•
•
•
Interlock wall stones with chimney stone
Free-standing
Wall logs interlocked in stone or brick
Metal ties to wall framing (20th century)
Metal bracing within wood framework
(modern zero-clearance chimney piping)
Attachment Methods (cont.)
Attachment Methods (cont.)
Lined Flue
• Inside of chimney
construction contains
flue “pipe” or “lining”
that minimizes
openings, joints, or
crevices along vertical
path of heat, smoke,
embers
Metal Chimney Liner
Tile Chimney Liner
Liner Characteristics…
• Each type of liner has it’s benefits and
drawbacks…
– Metal is expensive, but crack resistant and often
installed in one piece top-to-bottom.
– Most common sizes are 6- and 8- inch
– Easy connection to wood/coal stoves
– Can be routed through some twists and turns
– Can retrofit old, unlined flues
Liner Characteristics (cont.)
• Tile, or terra cotta, offer wider passages
than metal and are less expensive than metal
• Not used in retrofits or relining of existing
flues
• Susceptible to temperature extremes and
settling of foundations, causing cracking
• May consist of several joints
Zero-Clearance or Prefabricated
Metal Chimney Flues
• Developed nearly 25
years ago to service
the growing
alternative heating
market
• Consist of multiple
layers of stainless steel
separated by fireretardant insulation
Unlined Flues
• Found in many homes
built prior to 1930
• May be of stone or
brick construction
Unlined Flues (cont.)
Fire Spread Characteristics
Tile/Terra Cotta Liners
• Cracks appearing over time and temperature
extremes provide openings for hot
ash/embers to exit the flue and contact
adjacent combustible framing members
• May also provide path into void spaces,
carrying sparks into area containing
combustibles (attic, behind knee wall)
Terra Cotta/Tile Liner (cont.)
• Subject to degradation
from rain, ice, snow
• Mechanical damage
from improper
cleaning, previous
fires
• Damage introduced
from exterior forces
(wind, trees)
Metal Chimney Liners
• May warp from
extremes in
temperature (burning
stove too hot)
• Improper attachment
of flue sections
Metal Flues (cont.)
• Joints may be open, allowing sparks and
embers to escape into void and combustible
spaces adjacent to chimney, permitting fire
spread and slow detection of same.
• Stainless steel tubular liners are used in
older unlined retrofitting, often resulting in
turns and twists permitting build up of
creosote and animal nests.
Creosote Buildup
• Creosote is a
byproduct of
INCOMPLETE
combustion.
• Adheres to tile,
unlined, flexible
metal, and joints in
flue liners
Creosote (cont.)
• Relatively cool temperatures in upper portion of flue
condense products of combustion into potential “time
bombs” on liners.
• Can be minimized by burning proper fuels (seasoned
wood) at proper temperature recommended by
stove/fireplace manufacturer
• Creosote is black or brown in appearance with a crusty or
flaky consistency. It can be tarry, drippy and sticky or
shiny and hardened.
• Regardless of the physical presentation of the creosote, it is
highly combustible. If the build-up of the volume of
creosote is sufficient, it is possible to start a chimney fire.
Animal Nest in Chimney Flue
Retrofitting Unlined Flues
• It is common to find older, unlined
chimneys outfitted with new style flexible,
stainless steel tubular liners
• Often connect to wood stove or insert
• May be placed in unlined flue surrounded
by fire-resistant material such as a
vermiculite/gypsum mix
Prefabricated Metal Chimneys
• Have Class “A” fire rating and may be used
inside of wooden box framing according to
building codes and Underwriter’s
Laboratories test results
• Lock together in a twisting motion
• Are NOT fire PROOF!!!
Identifying Fire Presence and
Control Options
Caller Complaints
• Hear persistent “roaring” sound from upper
flue area
• Smoke from chimney when no active fire in
fireplace/ stove
• Haze/smoke odor in upper floors of house
and/or attic
• Walls adjacent to chimney hot to touch
Chimney Fire Size-Up
• Burn explosively
• And are generally noisy and dramatic enough to be
detected by neighbors or passersby.
• Victims of them compare the sound of the fire to a low
rumbling noise like a freight train or low-flying airplane.
• Flames have been known to shoot from the top of the
chimney accompanied by dense smoke.
• The first indication of a chimney fire is usually the noise
— a roaring sound that grows louder as the fire intensifies,
reaching temperatures of up to 2,000 F.
Chimney Fire Size-Up (cont.)
• Not all chimney fires are visible from the exterior. Some
are slow-burning fires, lacking the levels of air or fuel
found in the large, eye-catching visible fires.
• The volume of fire, smoke and heat from this type of fire
can push hot gases out of existing cracks in the chimney
mortar or cause internal connectors to fail. When viewed
from the exterior, large smoke volume and sparks and fire
can extend several feet above the chimney.
Video
Video to Demonstrate the rapid rate and damage of a chimney fire on Terra Cotta
and Metal flues and liners.
https://youtu.be/4gfAEsSTB7c
Video to demonstrate damage to an older home. (Show only a short version.)
https://www.youtube.com/watch?v=mUzYXddccgc
Examples of Damage
https://www.bing.com/videos/search?q=chimney+fire&&view=detail&mid=52B1
C95ED2AA7EB5785A52B1C95ED2AA7EB5785A&&FORM=VRDGAR
Fire Department Dispatch
https://www.bing.com/videos/search?q=Fire+department+dispatched+to+a+chimn
ey+fire&&view=detail&mid=CCDD1E9BC4F29A720ABDCCDD1E9BC4F29A7
20ABD&&FORM=VRDGAR
Safe Use of a Tower or Ladder Truck
https://www.bing.com/videos/search?q=Fire+department+dispatched+to+a+chimn
ey+fire&&view=detail&mid=07F511E480F500BC5F6E07F511E480F500BC5F6
E&&FORM=VRDGAR
Fire Control Tactics
• Chimney fires should be dispatched as a full-structural response until
the size, location and access impacts are assessed.
• Ensure the occupancy is fully evacuated. And because all fires are
unpredictable, firefighters must wear full PPE, including SCBA.
• Stretch a preconnect line to the front of the structure in case the fire is
larger than initially anticipated.
• Chimney fires rarely occur when the weather is good, so watch your
footing in wet and/or freezing-rain conditions when accessing the roof.
• Thermal Imager A MUST!!!!
– Demonstrate the imager from 801
• Get personnel ABOVE and BELOW fireplace/stove-check walls, floor
space adjacent to flue—attic
• Check flue clean out (if present)
• Roof crew to check openings at top
Tactics (cont.)
• Remove active fire from firebox
– Review Tools from 801 for performing this procedure.
– Maximize your customer service skills by using floor runners and fire-retardant
salvage covers near the fireplace during salvage and overhaul. Careful cleanup
can earn your department valuable praise from the homeowners
• Closely monitor flue for active flames
– Visually inspect the chimney with a mirror to determine the extent of the fire.
• If the fire is contained within the flue system, move on to chimney
fire-specific extinguishment methods.
– Consider use of dry chemical extinguisher or “chimney bombs” (dry chem in
plastic baggies dropped from top of chimney)
• Pressurized water extinguisher and/or preconnect should be LAST
RESORT on the chimney fire or fireplace.
• Send a recon team directly to the attic and make sure that the fire
has not extended into this space or the cockloft. Inspect the firebox
itself and as much of the chimney in the inside of the home as
possible.
Tactics (cont.)
• Once fire controlled, occupant must be
directed to have licensed chimney sweep
clean and inspect chimney PRIOR to ANY
additional usage.
• Officer should document this on NFIRS
report.
Points to Consider…
• Successful control of chimney fires requires
time and patience
• Continual monitoring of all adjacent
combustible areas required during
operations
• Older, unlined flues often contain structural
framing members tying chimney to house
Other Important
Considerations…
• EARLY laddering of roof
• Use of chimney chains to clear flaming
creosote (if available on scene)
• Aggressive investigation of adjacent void
spaces
• Identification of lined vs. unlined flue
Summary
• Firefighters should be familiar with the
various chimney types
• Understand particular hazards of each
type of flue
• Recognize signs of active fire situations in
flue and execute proper control methods
Summary (cont.)
• Make every attempt to control fire while
minimizing damage to chimney/flue
structure
• Ensure safe operations when working in
poor lighting and on wet/icy or steep roof
pitches