As the nights get cooler, the more we look forward to the warmth and beauty of a wood-burning stove or fireplace. However, chimneys used with wood-burning stoves, fireplaces, and fireplace inserts are potential fire hazards. Most chimney fires are ignited by the creosote, which is a black tar-like substance that builds up inside the chimney with normal use. Some homeowners may not even be aware that such a chimney fire has even happened. However, the damage caused by such an undiscovered flare-up could leave the chimney susceptible to a large, more damaging fire.
In addition, most fires involving either masonry or prefabricated metal chimneys occur because of improper installation, use, or maintenance. These are the common causes of fires:
- Chimney improperly installed too near wood framing.
- Thermal insulation installed too near the chimney.
- Passing the chimney or stovepipe improperly through a wall or ceiling, resulting in ignition of wood framing.
- Rusting or corrosion of the interior lining of metal chimneys.
- Separation of the seam, buckling, or collapsing of the inner liner of metal chimneys, resulting from a fire that is too hot. This is particularly common in fireplace inserts and high-efficiency stoves, or from creosote fires.
It should be kept in mind that even with proper installation, it is important that masonry or metal system should be checked frequently for soot buildup, creosote deposits, or physical damage. A simple visual inspection should be conducted biweekly during heavy use. If creosote buildup is noticed or a problem is suspected, a qualified chimney repairperson should perform a thorough safety inspection.
Even when a heating appliance is property installed, people with either metal or masonry chimney systems should frequently check the chimney for creosote deposits, soot build-up, or physical damage. This involves only a simple visual examination, but it should be done as often as twice a month during heavy use. If you see heavy creosote buildup, suspect a problem, or have had a chimney fire, a qualified chimney repairman or chimney "sweep" should perform a complete safety inspection.