As summer continues to become just a distant memory and leaves begin to fall from the trees, many of us are looking at needing to heat our homes.

Cosy nights in snuggled by an open fire is a romantic thought for many. But these winter evenings can soon turn into a nightmare. If the correct maintenance and precautions aren’t followed, your cosy open fire can quickly turn into a disaster.

According to statistics released by the Home Office, there were 4,086 chimney fires in the year ending September 2017. And it’s not just homes that are at risk either. Last year, chimney fires in licensed premises were one of the most common incidents attended to by Kent Fire and Rescue. And nearly all of those fires were caused due to a build-up of debris in the chimney and a failure to get them swept.

So what causes a chimney fire?

Almost all chimney fires are preventable. And while a failure to sweep a chimney is the most common cause, there are other causes you should be aware of to ensure appropriate precautions and measures are put in place to prevent one happening to you.

Improper appliance sizing
If an appliance is too large, it will never reach the high temperatures needed to volatilise all the fuel within the wood burned. The unburned fuel will then pass up the chimney as smoke and condense within the flue as extremely flammable creosote.

Burning unseasoned or wet wood
Only seasoned wood should be used as fuel; unseasoned, fresh or green wood has no cracks, the bark is still firmly attached, and it’s more likely to sizzle or bubble when placed on a fire. Unseasoned wood also creates a lot more smoke and creosote as it burns, due to its higher levels of moisture.

Overnight burning / prolonged smouldering
Fires, stoves, and burners should never be left unattended. Leaving them smouldering at low temperatures, even when you’re present, should also be avoided. The aim of an efficient flue is for the byproducts of the fire to move up the flue as quickly as possible, before they have a chance to cool down. However, when a fire is left smouldering, the smoke and gases cannot escape quickly enough, resulting in a build-up of tar and creosote in the chimney.

Infrequent sweeping and cleaning
As mentioned above, there are various conditions in which a build-up of soot, ash, tar and creosote can occur. If this is not avoided, and not swept/cleaned properly and frequently enough for the type of fuel you’re burning, it can cause devastating damage. The leftover gases, tar, soot and creosote are extremely flammable and can easily ignite from a stray spark.

Depending on the type of fuel you’re burning depends on how often you should have your chimney swept:

Oil – Once a year
Gas – Once a year
Bituminous Coal – Twice a year
Wood – Up to four times a year
Smokeless Coals – Once a year minimum

Chimneys also need regular sweeping to ensure that they are free from other flammable debris, such as birds nests.

What are the signs of a chimney fire?

Chimney fires can easily happen and due to the nature of them, can often smoulder and go undetected for some time, posing a great risk to you and your property.

If you notice any of the following signs or suspect a chimney fire, evacuate the premises straight away and call 999.

Look out for:

  • A roaring sound that increases in line with the fire’s intensity
  • Loud cracking, popping, or rumbling noises coming from the chimney
  • Embers falling from the chimney back into the fire
  • Black smoke, sparks, or flames coming from the top of the chimney
  • Flames appearing several feet out of the chimney
  • The walls of the chimney or adjacent walls to the chimney becoming hot to touch

Chimney fires can quickly escalate, spreading to other areas of a property. So if you suspect something isn’t right, act fast. It’s better to have a false alarm than to risk lives.

What damage can a chimney fire cause?

A chimney fire shouldn’t be taken lightly. It has the potential to cause devastating damage to your entire property, especially as they often go undetected for some time.

During a chimney fire, temperatures can reach up to 1,100°C inside the chimney, with some burning materials able to reach 1,200°C. And as the chimney heats, it expands, potentially causing plaster to crack and blow. This can result in the minimum of needing the lining replacing, or it can actually cause structural problems to the chimney itself.

If you have a stainless steel flue liner, the chances are almost guaranteed that it will need replacing after a chimney fire. The heat from the fire causes the crystalline structure of the steel to change and if you try to continue using it after a fire without replacing it, it will corrode very quickly. Stainless steel is also prone to buckling and changing shape when exposed to extreme temperatures.

If cracks appear in your chimney (or there were cracks and gaps already present), then smoke is unable to fully escape. This can result in smoke coming back down the chimney and entering your property, causing smoke damage to areas inside your building.

Carbon monoxide is also a huge risk. The colourless, odourless, tasteless gas is produced by the incomplete combustion of carbon-based fuels. So even if the chimney fire doesn’t cause significant damage to your property, your health and life can still be in great danger.

Preventing Chimney Fires

Almost all chimney fires are preventable when the correct usage, precautions and maintenance are carried out.

Follow the steps below to ensure you minimise the risk of experiencing a chimney fire:

  • Ensure your chimney is swept regularly enough for the type of fuel you’re burning
  • Do not burn wood with a moisture content of more than 17%
  • Avoid overloading the fire grate
  • Always use a fire guard
  • Check the exterior of your chimney for cracks and moss growth
  • Always ensure the fire is out before going to bed or leaving the house
  • Never leave flammable items, including clothing, near the fire
  • Avoid storing items near the chimney in the loft – should there be a fire, these act as quick fuel for a chimney fire to spread
  • Do not interrupt air supply by blocking air vents or air bricks
  • Ensure the right size appliance is being used
  • Ensure manufacturers guidance is followed and the right fuel is used
  • Ensure working smoke and carbon monoxide alarms are fitted

It is vital to recognise that an open fire is a source of ignition and therefore should be identified as such, especially within fire risk assessments for commercial properties.

For more information on fire safety, contact your local fire service.