Santa Loves a Chiminea

For those of us with fireplaces that old Christmas tree is looking like a handy source of firewood, but in fact it’s one of the worse things you could do to your chimney. Most people have never even heard of chimney fires, but they do happen in our area. Given the catastrophic damage they can do in a very short amount of time, its well worth knowing a little something about how they happen.

Chimney fires occur when built-up creosote inside a chimney ignites. Creosote forms from the condensation of wood burning by-products (smoke, water vapor, hydrocarbon gases, tar fog and minerals) along the inside of the chimney flue. This material catches fire easily and produces fires of 2,000 degrees Fahrenheit – hot enough to melt mortar, crack tiles and cause liners to collapse.

Chimney fires are classified as either “slow-burning” or “free-burning.” Slow-burning chimney fires smolder inside the chimney due to restricted air or smaller amounts of fuel. Their low-key presence can be potentially more dangerous because they build up heat rapidly with no obvious signs of damage. Compromising the flue leaves the house more vulnerable in the event of another chimney fire. Free-burning chimney fires are loud and dramatic, producing noise, dense smoke, and an intense, hot smell. Sparks and hot materials shoot out of the top of the chimney, which can in turn ignite roofing or nearby trees.

If you notice signs of a chimney fire, get everyone out of the house, including yourself, and call the fire department. If sparks are coming out of the chimney, use a garden hose to spray down the roof (not the chimney) to keep fire from spreading to the rest of the house. Afterwards, call a CSIA Certified Chimney Sweep to inspect for damage. Chimney fire damage and repair normally is covered by homeowner insurance policies.

Do not use the chimney until it has been repaired! Using a damaged chimney can cause a number of problems such as flue gases and carbon monoxide backing up into the house, structural damage or a house fire.

The best defense against chimney fires is a good offense:
Have your chimney checked annually by a CSIA Certified Chimney Sweep and cleaned as needed. To locate a CSIA Certified Chimney Sweep, click here to visit the CSIA web page. This site has more information on chimney “health” and good safety practices. If you are about to buy or sell a home that has a chimney, be sure to get an inspection.

Build good fires! Use only dried, seasoned woods and build smaller, hotter fires that produce less smoke. (See the previous blog for fire-building information.) Never burn cardboard boxes, wrapping paper, trash or Christmas trees; these produce sparks and smoldering ashes which can spark a chimney fire. Always let the fire burn itself out. Extinguishing a fire too quickly causes thermal shock to the flue tiles. Thermal shock weakens the tiles, creating a more open pathway to the combustible materials of the house.

Creosote Sweeping Logs are available at local home improvement and hardware stores for around $15. These logs do not replace regular inspections but they can help maintain a cleaned, structurally sound chimney. Maintain a safe and healthy chimney so it will be ready for that one day a year when you Really Do Need It (when Santa comes to town) and save that Christmas tree for the chiminea. Best wishes and (belated) Happy Holidays!

This blog was written for Paul LaGrange’s BuildWrite website and was originally posted on January 6, 2009.


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