If you’ve wondered what chimney fires are all about, we welcome you to read on.

Here, you’ll find as much information regarding this subject matter. We’ll be discussing the causes of chimney fires, tips on how to limit exposure to such risks, and other relevant information.

Chimneys have long been used in buildings to convey or expel hot toxic gases and smoke produced from a fireplace, furnace, incinerator, or boiler. Chimneys are still widely used due to the convenience offered.

However, there are times when chimney problems occur. A common example of such is a chimney fire accident.

Signs of Chimney Fires

Chimney fires can be very deadly. The best strategy to adopt is having it inspected as frequently as possible.

When a technician comes around, they check for several signs including discolored and distorted rain cap, damaged roofing materials due to hot creosote, visible cracks in masonry as well as collapsed tiles among several other signs.

SEE: Fire Pit Wind Guards

What Causes Chimney Fires?

This is quite a common question asked by a lot of homeowners. This is a very vital question to ask as knowledge obtained can greatly help in preventing a chimney fire outbreak.

The main causes for chimney fires include infrequent sweeping or cleaning and wrong appliance sizing.

Others include prolonged burning of wood in wood stoves as well as burning the wrong type of wood. What more? A steady buildup of creosote and soot in the flue can spark an outbreak of chimney fires.

READ: Spark Arrestor For Chimney Systems

Let’s further expand on these for more clarity.

  • Infrequent Cleaning or Sweeping

As a chimney gets used continually, a buildup of various waste products considered by-products of the burning fuel happens.

Wood stoves for instance are designed to use wood as burning fuel. Now, during the burning or combustion of such wood, several by-products are released.

These by-products range from smoke, fog, hydrocarbons, water vapor, wood particles that haven’t been burned, and a wide range of gases and minerals are released. A chimney is designed to channel these unwanted wastes and gases out.

However, not all of these completely escape the outlet.

Some of these condense or form a residue that sticks to the inner walls of your chimney. Such flaky deposits are also known as creosote and mostly appear brown or black. The problem here is; creosote is known to be highly combustible.

Therefore it’s only a matter of time before chimney fire results especially when not frequently cleaned.

  • Wrong Appliance Sizing

Another cause for chimney fires is the use of the wrong appliance size. So, how does this result in a chimney fire?

An appliance considered too large won’t generate the right amount of temperature needed to fully burn all the fuel contained in wood.

With inadequate heat generated in completely burning or combusting the wood, the rest of the fuel is channeled up your chimney. This results in the formation of creosote which is no doubt a highly volatile fuel.

However, this can be avoided by getting the right appliance size. This helps encourage more combustion or burning of fuel, thus limiting the escape of unburned fuel.

  • Prolonged Burning of Wood

When wood is burned for an extended period continually, the temperature within the chimney is raised significantly. Now, such high temperatures can easily ignite the creosote deposits on the chimney wall. Such can be catastrophic and poses grave danger to occupants within the building.

It is best to avoid leaving fires to burn overnight. If you must, your chimney must be cleaned regularly to clear out any creosote or soot deposits. This cleaning activity helps reduce the chances of a fire outbreak.

  • Burning the Wrong Type of Wood

Is there a wrong type of wood you shouldn’t use in your chimney?

Yes. There are the wrong types of wood! Why are these wrong and unsuitable for use as combustible fuels? They are because they burn fast, thus creating lots of smoke and leaving behind a few coals.

Such smoke means the inner surface of your chimney walls is easily coated with soot or creosote.

Examples of woods you shouldn’t use as heating fuels include cypress, pines, and firs. These are known as softwood and have the combustion characteristics mentioned above.

Combustible Fuels Used In Chimneys

Now, there are several types of combustible fuels used in chimneys. These chimneys are specially designed or adapted to such fuels.

Examples of chimney fuels include wood, oil, gas, smokeless coals, as well as bituminous coal.

When using any of these, you’re expected to follow safety precautions to prevent potential chimney fires.

  • Wood

Chimneys, where wood is used as fuel, must be routinely inspected. Wood fuels result in the most deposits due to the release of water vapor, wood particles, fog, and smoke among others.

  • Oil

If you use oil as burning or combustible fuel, you should consider sticking to a chimney cleaning frequency of once each year. When compared to wood, you’d notice that the recommendations for cleaning are much less.

The reasons are obvious; fewer substances are released during combustion thus making it more efficient than wood.

  • Gas

Gas is yet another combustible fuel which when used, also requires a chimney cleaning frequency of about a year. Gas is also considered a much more efficient fuel compared to wood.

  • Smokeless Coals

When using smokeless coals for heating, your chimney will need to be cleaned at least once every year. This frequency is sufficient enough to clear out combustible deposits that may result in chimney fires.

  • Bituminous Coal

 Bituminous coal is considered dirty fuel when compared to smokeless coal, gas, and oil. The wastes given off can easily result in the gradual accumulation of soot or creosotes which can cause chimney fires.

Putting Out A Chimney Fire

In our discussion about chimney fires, we’ll need to face the elephant in the room. In this case, you’ll need to know what to do when a chimney fire breaks out. When faced with a chimney fire, you mustn’t panic.

Before you call for help, you can take certain actions to put the fire under containment. These actions are basically categorized into three; bombing from the top; and attacking from the bottom.

You’ll need to call for help.

  • Bomb from Top

Bombing from the top might sounds extreme, right?

Well, it isn’t what you might be thinking of. Bombing from the top involves the use of a dry chemical powder contained in sealable plastic bags. As the name implies, these bags are dropped down the top of your chimney.

When dropped into the fire, these bags melt and in the process release their contents. Its contents get released and travel or float upwards thus extinguishing the fire in the process.

  • Attacking from Bottom

To attack a chimney fire from the bottom, you’ll need to briefly open your chimney’s draft stop.

Care must be taken though as this might briefly increase the intensity of the fire. Next, immediately insert the nozzle of your dry chemical extinguisher and discharge it into your flue in an upward direction.

When your flue length is longer (especially where a two-story structure is involved), the adoption of both approaches may be necessary. That is, bombing from the top and attacking from the bottom.

  • Calling for Help

Calling for help is something you should strongly consider when dealing with a chimney fire. This experience can be scary and having little knowledge of how to contain the problem can worsen the situation.

It’s best to place an emergency call to 911. That way, you won’t have to deal with a delicate fire situation yourself. Plus, the risks of injury are greatly reduced.

Reducing Incidences of Chimney Fires

Every homeowner will want to avoid the horrors of a chimney fire.

Thankfully, there are several ways this can be achieved. Chimney fires can be limited to a greater degree by adopting the following practices.

  • Installing an Internal Probe Type Thermometer

More often than not, people are oblivious to the fact that internal temperatures (of chimneys) should be gauged.

To do this, an internal probe-type thermometer must be installed. This takes the temperature readings within the chimney and alerts to a possible increase in temperature beyond safety levels.

When this is noted, the temperature is dropped by regulating the burning fuel. This way, the possibility of experiencing a chimney fire is greatly diminished.

  • Regulating Air Supply

When fuel is used, it needs to be fully ignited. The air supply is crucial to achieving this.

However, a limit should be maintained. In other words, once the fuel is fully ignited, and the flue has attained the desired amount of temperature, regulation of air supply will be necessary.

This is meant to avoid over-firing which rapidly increases the temperature to excessive levels. The air supply should be maintained in such a way that temperature is maintained within acceptable levels.

  • Frequent Sweeping

This point cannot be stressed enough. Every burning season, chimneys accumulate combustible dirt easily. It will be necessary to stick to the cleaning frequency as earlier recommended.

  • Check the Moisture Content of Wood Fuels

Not every wood is suitable for use as combustible fuels in chimneys. Woods being used must maintain or have a moisture content of 17% and below.

Anything more than this increases the risk of a chimney fire developing as long as such recommendations are flouted.

  • Get the Right Appliance Size for Complete Combustion

Research has shown that fuels are not fully combusted when the right appliance sizes aren’t used. This is mostly the case with large appliances that hardly raise temperatures sufficient enough to volatilize all of the fuel within a wood.

By getting the right size of equipment, you’re helping to limit the possibility of such ever developing or happening.

  • Check Smoke Density

Smoke density is very crucial to understanding the combustion situation. Externally checking the density of smoke released through the flue helps ascertain if the right burning conditions are obtained.

Also, consider checking the level of combustion through any available glass panels.

  • Regulate Air Inlets in Multi-Fuel Stoves

Certain stove types are designed for multiple fuel use. To prevent these from creating chimney fires, you only need to regulate them using the air inlets installed for this purpose. You must avoid the use of dampers.

The reason why the use of fireplace dampers is not advisable is that these end up obstructing the free flow of exhaust from your stove. This, in turn, complicates its operation which may result in chimney fires.


The information contained in this article is targeted at helping you get a better understanding of chimney fires as well as why they happen.

Armed with such knowledge, you’re able to ensure your situation prevents this from ever happening to you.

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