Two Hidden Causes of House Fires: Pyrolysis and Batteries

Causes of house fires - Certified Chimney SweepsPeople who have fireplaces in their homes are usually aware that they need to be careful about preventing house fires. There are, however, some potential fire hazards in any home, even if it’s not a neglected chimney system. What’s alarming about two of these dangers is that they are largely unknown and hidden hazards that can result in deadly house fires. These two stealthy fire hazards are 9-volt batteries and pyrolysis.


Many people have never heard of pyrolysis, but it is something that it is important to prevent. Pyrolysis is a chemical breakdown of materials caused by exposure to extreme heat. These materials eventually ignite, even without a direct flame. Heat and oxygen are all that is required for pyrolysis to occur.

The basic scenario that results in pyrolysis is when combustible materials are placed in close proximity to a heat source that produces temperatures of 212°F or more for a long period of time. Pyrolysis is one of the major causes of structure fires throughout North America.

There were two house fires that occurred in a 300-home residential tract in California in 1993, and fire inspectors determined that pyrolysis was the cause of both fires. The fire department set out to try and make sure all of the homes in the residential tract were not in similar danger of catching fire. In the case of the two homes that burned, zero clearances existed between furnaces and plywood, causing the plywood to ignite. The fire department did not have the authority to require inspections of all of the homes; so they sought help from the homeowners’ association to have all of the furnaces inspected. It was determined that faulty installation of furnaces was causing pyrolysis and a very real threat of house fires throughout the neighborhood.

It is practically inevitable that pyrolysis will occur when solid-fuel stoves, fireplaces, and furnaces are installed incorrectly. The process can take months and sometimes even years, when an unexpected fire ignites. To prevent this fire hazard, allow for at least the minimum recommended space between combustible materials and heat sources, according to manufacturers’ instructions.

One cause of pyrolysis is when a fireplace is continually used after the chimney liner has been damaged. Combustibles near a chimney can catch fire from pyrolysis when there is even a small amount of damage to the liner.

It’s important to be sure that walls, furniture, and other combustibles are not positioned too close to heat sources, as another way of preventing pyrolysis.


Prevent House FIres - Atlanta Chimney ServiceUsing 9-volt batteries is a common household practice, but what many people do not know is that if the battery terminals of these batteries touch, a fire can easily be sparked. This very thing happened to homeowners not long ago; as a result, their beautiful home burned down and was a total loss. The batteries had been discarded and were in a recycling trash bag in the garage. The bag was shifted, and the batteries ended up touching, starting a fire that quickly spread.

To diffuse the danger of 9-volt batteries that are not in use, simply place duct tape over the terminals.

Our professional chimney technicians can help families to prevent pyrolysis because during inspections, the chimney liner can be closely inspected, using special equipment. Contact us today to schedule your annual chimney inspection and ensure the safe use of your fireplace and chimney.

Chimney Solutions, Inc.
1155 McFarland 400 Drive, Alpharetta GA 30004
Office 770-255-1300

Chimney Sweep / Chimney Repairs / Chimney Liners / Fireplace & Stove Service
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Chimney Solutions
1155 McFarland 400 Drive AlpharettaGA30004 USA 
 • (770) 255-1300
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