A chimney fire occurs when soot and tar deposits in the flue ignite. It manifests as a loud roar in the chimney, sparks and thick smoke from the chimney head, or cracking of the masonry. The risk increases with the time elapsed since the last cleaning, therefore Decree 34/2016 Coll. Sets regular deadlines according to fuel type, described in the article Chimney cleaning: deadlines by fuel type and priceThe most at-risk are chimneys serving solid fuel appliances, where soot and tar accumulate most rapidly.
What to do when a chimney is on fire
First of all, call the fire brigade on 150 or 112. You will never extinguish a chimney fire with water; rapid cooling may crack the chimney masonry or lining. If it is safe to do so, close off the air supply to the combustion chamber (door, damper), switch off the appliance and move away from the chimney. Monitor whether heat is spreading through cracks in the chimney into adjacent structures and attic spaces. In a panel building or apartment block, it is advisable to also alert neighbours whose flats share the same chimney stack, as heat may spread into their premises as well.
Do not attempt to extinguish a chimney fire on your own before the fire brigade arrives, other than by closing off the air supply. Extinguishing or inspecting the chimney from inside is pointless and dangerous. After attending to the incident, the fire brigade will usually assess whether it is necessary to evacuate residents from the flat or if ensuring ventilation and allowing the chimney to cool down is sufficient.
Why an inspection is mandatory after a fire
Decree No. 34/2016 Coll. Classifies a chimney fire as a situation where an inspection of the flue gas path is mandatory before the chimney can be used again. High temperatures during a fire may damage the masonry, joints or liner, even if this is not visible from the outside. The inspection technician will assess whether the chimney is safe for further operation after the fire, or whether repair, milling and a new liner are required.
Until the inspection is carried out, an appliance connected to the affected chimney should not be restarted again, even a seemingly functional draft does not indicate hidden cracks in the masonry through which flue gases or heat could escape into the building structure.
Most common causes of chimney fires
The vast majority of chimney fires occur in the same way, through long-term neglect of cleaning the flue gas path in solid fuel appliances. This is also contributed to by heating with undried wood, which burns at lower temperatures and produces more tar, or by operating a chimney for a long time without an annual inspection during which a chimney sweep would have detected deposits in time. The risk also increases with chimneys that have been out of use for a long time and are reconnected to an appliance without a prior inspection.
Insurance and documentation
In the event of damage caused by a chimney fire, the insurance company always verifies whether the owner complied with regular inspections and cleaning of the flue gas passage in accordance with Decree 34/2016 Coll. If documentation is missing or expired, compensation may be significantly reduced even if the fire itself did not cause any structural defect. An inspection report following a fire is then a prerequisite for the chimney to be used again. What an inspection report contains is explained in our article. Chimney inspection: price, obligation and procedure.
In practice, it is therefore worthwhile to keep records of cleaning, checks and inspections neatly stored in one place, ideally together with other property documents. When dealing with an insurance company after a loss event, it is then possible to quickly prove that all obligations have been met, thus avoiding unnecessary reductions in the payout.
Before another fire occurs
The best prevention remains adhering to cleaning deadlines and annual inspections: the article explains the difference between these tasks. Chimney inspection, cleaning and certification: the differencesIf you are unsure when the chimney last underwent an inspection or check, it is wiser to have its condition verified in advance than to deal with the aftermath of a fire. On top of that, prevention costs less than repairing the chimney and carrying out an inspection after an incident combined.
It is also worth paying attention to the type of fuel and how you load it into the appliance, wet wood, overheating or burning waste increase soot and tar formation much faster than normal operation according to the manufacturer's instructions. Combined with adhering to cleaning deadlines, these are the two most effective measures entirely within the owner's control.