See what our readers had to say
Bobby Halton and Bill Carey
This month’s subject came from a reader curious about limiting damage during chimney fires. The February Roundtable question is:
“How does your organization manage chimney fires? What tools and techniques do you employ?”
Dr. Candice McDonald
Chimney fires are not uncommon in rural Ohio, where many members of the community rely on wood to help heat their homes in an effort to save on heating costs. The first technique in combating a chimney fire is fire prevention education. Many home owners fail to have their chimney professionally inspected and cleaned annually. Many homeowners are unaware that the buildup of creosote can lead to a chimney fire that can warp metal and crack masonry. Homeowners are also unaware that a small crack or hole in the flue could be the perfect opening for fire to spread into their home.
Responding to a potential chimney fire starts with an exterior size-up, that involves looking and listening for signs of a chimney fire. Can you hear a roaring noise, like a freight train? Can you visually see flames or dense smoke extending from the top of the chimney? Is there signs of a fire sneaking out of existing cracks in the masonry?
It is important to note, fire may not be visible from the flue. It is key to identify the location as part of the size-up. It is also critical to ensure the fire has not extended into the attic or other hidden spaces within the home. This is where a thermal imagining camera can be beneficial.
Although there are several ways to extinguish a chimney fire, the use of a chimney bomb from the top is one method commonly used in our area. The chimney bomb is made up of ABC dry chemical extinguishment agent in a sealed plastic bag. These bags are dropped from the top and as gravity pulls them down the bag melts and releases the powder into the flue for extinguishment.
It is also important to remove the fire load and hot ashes from the firebox inside the home. After putting out the fire in the firebox, the fire load should be placed in a metal salvage bucket (which you should carry on your truck), and emptied outside where you can wet it down using a pre-staged attack line. It is critical to make sure that the fire load and ashes are completely extinguished before you leave. This can be a messy job, laying a tarp down during this salvage operation can protect the homeowner’s flooring from becoming soiled.
Chimney fires are typically handled by carefully extinguishing the logs with a very light water can spray diffused with a finger. Logs are removed via salvage tub. A dry chemical extinguisher is discharged into the chimney above the damper and the damper is closed to stop the air flow. Simultaneously, crews go to the attic and roof and inspect with thermal imagers. If the first dry chemical extinguisher, does not extinguish, this process is repeated by opening the damper, discharging additional dry chem extinguishers and then closing the damper. Crews monitor or take additional actions as needed.
After a good size-up of the chimney and we ensure the damper is closed we decide how to attack the fire. We have three methods for consideration;
- Chimfex – This is device looks similar to a road flare that you throw into the fire box and It extinguishes the chimney fire by reducing the Oxygen in the flue.
- Dry Powder Extinguisher – It basically involves using a dry powder from the bottom and involves opening the damper (which could intensify the fire) and placing the nozzle of the dry powder extinguisher into the chimney past the damper and discharge the dry powder. Keep damper open for minute then close and reassess the fire. This method tends to be a bit messy so it would be a good idea to consider tarping the floor and furnishings in the room as a public service to the occupants
- Handline – This should be a last on your list to try due to the damage this will cause.
It’s important to make sure the fire hasn’t spread from the chimney into attic or wall spaces, so inspecting this spaces may be needed.
Depending on the circumstances, our department sends the truck crew to the roof to access the top of the chimney. Their job is to ensure there is no obstruction at the top of the chimney. From that point we would typically just use a hand line with a fog nozzle in the house and up the chimney. At times I’ve used a cellar nozzle as well. The first arriving engine officer will make entry to the house and will utilize a TIC to determine if the fire has breached through the chimney and is into the walls. If this is the case an additional engine company will make entry to assist.
Remember when forcing into the walls around the chimney to be cautious of weakening chimneys and load bearing members. Other crews on scene may also be used to assist with salvage to be able to divert the water that’s coming down from the chimney. Depending on the size of the fire though it may be more beneficial to fight the fire from the top of the chimney. However, we attempt to steer clear of that due to the chances of pushing the heated gases and smoke down and back into the house, plus the chimney creates a natural ventilation area for the smoke to go.
Of course building construction does come into your decision making process but to give a broad based answer (using water is always the last resort).
- Life safety of homeowners
- but the basic system is to keep the damper open
- if fireplace has doors, shut them and then open them just enough to squeeze a small amount of a dry chemical extinguisher into the fireplace chimney area
- close the doors, the natural air movement will draw will the dry chemical extinguishing agent up the chimney.
- always have someone at the roof/chimney area to advise progress
- may need to repeat step 2 more than one time
- always check for fire extension
- overhaul if needed
- property conservation
My department responded mostly in a suburban and rural area where wood stoves are predominant for heating and in some cases cooking so the department had their fair share of chimney fires. The fire service tends to respond casually as the thought process is the fire is generally contained within a brick lined or un-lined chimney or a metal flu that is screwed together at the joints. Many times these “simple responses” can turn into a full-fledged structure fire. Our crew instructions are to prepare to fight a house fire.
One of the most serious issues is the identification of the fire spread into hidden spaces due to the sheer energy, thermal pressure and violence of the burning material consisting mostly of creosote that can shake connections or affect the integrity of a flu or chimney
Firefighters have reported a “jet engine” sound at the bottom and top of the chimney or flu due to the rapidly combustion of the material and the pressure and vibration that is associated with that process.
In any of these events, command needs to be established, removal of the occupants and simultaneous with extinguishment is checking for extension within the structure. Spread of the fire can be accomplished with visualization of the affected void spaces (if access is available) and/or using a TIC.
Suppression techniques usually involve removal of the fuel source – removing the burning wood or turning off the gas: use a dry power bomb from the top of the chimney or a dry-chem extinguisher into the fire box and allow the updraft to suppress the fire and after the fire has cooled use a chimney chain to remove burned or unburned material allowing it to fall into the fire box, which is placed in a metal carrying box and removed from the structure.
It is advised that water is the last suppression method of choice as it may crack an intact ceramic flu or loosen mortar or bricks in an unlined brick chimney or cause rapid cooling of a metal flu/chimney causing expansion or contraction of the joints possibly causing separation of the joints allowing fire spread into void spaces or into the attic.
Safety of the firefighters is imperative as well. Standing on a slippery roof is dangerous to the firefighters and fire operations. Wear firefighters must wear PPE and anti-slip footwear. Our department had two sets of “corks” or “calks”, typically a logger boot with spikes and these can purchase as slip-on’s over bunker boot to ensure safe footing.
As many of these events occur in the evening or night time, adequate lighting is a must either through the use of individual lights or scene lighting.
Remember to use salvage covers on the floor surrounding the operational area and in the entrance and egress pathways for firefighters and deploy a CO monitor to measure the level of CO in the house and perform overhaul to prevent re-ignition.
Inspection of the entire chimney or flu system to determine any breaches in the chimney structure must be made by a qualified inspector prior to continued use.
I think the most important issue when responding to a chimney fire is not to take it too lightly. Company should not be returned unless the fire is definitely out or definitely under control and has no chance of spreading. The incident commander should be the first one to think of fire is burning the last one to think it’s out. Companies should be assigned to check all areas in the house where the chimney fire may spread to the house proper. This includes the basement and all floors especially the attic. Company should be sent to the roof but be very careful because old chimneys do not provide good handholds. Lines should be stretched everywhere that openings are made. I have seen or heard of departments using plastic bags filled with dry chem dropped into the chimney. When the bag melts the agent is disbursed. I always thought that was a good idea. Damage to the structure should be in line with the emergency at hand. Fear of creating too much damage has burned buildings down. Thermal imaging equipment is a must. Opening up is a necessity. As always, solid policy and solid recon should guide all activities
When managing chimney fires my organization uses traditional tools
and techniques depending on the severity of the fire. If the fire is
primarily contained to the flu and fire box, interior operations
include; a dry chem extinguisher, tarps to protect the floor, and metal
bucket and shovel to clear out the firebox. Be sure to clear the entire
box, and remove the contents from the structure. Utilize a trash or
bumper line to soak everything down.
Exterior operations include a 360 by command, laddering the roof, utilizing chimney bags (plastic baggies filled with dry chem), and a weighted chain to clear the built up creosote in the flu. Try to avoid using a can or line in the flu if at all possible as this can cause irreparable damage due to the rapid change in temperature. Obviously this is not a concern if the fire has extended outside the chimney.
Once the fire has been contained, crews are sent to check for extension. It doesn’t take much to degrade the mortar and come out of the chimney between floors or in the walls. Don’t forget to check the attic or cockloft for extension as well, too easy to have hidden fire resulting in an embarrassing call back for a “rekindle.” Be aware opening the attic scuttle will allow air in feeding any fire. Always use your own ladder and not the attic fold down. Utilize TICs and feel the walls to check for heat or hidden fire. Be sure to check for CO during and after operations, and advise residents to have the chimney thoroughly examined by a professional before using it again.
If the fire has extended out of the box or flu at all, it is treated like a traditional structure fire: lines are pulled, additional manpower is called for, and overhaul is completed.
Priority 1 is not to become complacent. Understand that a “routine/nuisance chimney fire” has the potential to spread to combustible void spaces such as attics and in the space between ceilings and floors supported by parallel chord floor trusses. Consider a chase enclosure for a flue running up the side of a two story house. If there is no separation between the chase and the floor truss voids, fire can spread from a faulty flue vertically in the case and horizontally at each floor level; just at it would in balloon frame construction.
Accordingly, operate at a chimney fire the same way you would for a fire in an old balloon-frame house: Although it may be apparent that there is a fire in the attic you must examine lower levels. Unsuspecting firefighters taking their hose line to the second floor to fight an attic fire may not realize that they have fire below them burning in the floor truss voids.
Note: Responses are solely the opinion and views of the individual and have only been edited for grammatical reasons.
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