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Preventing Creosote Chimney Fires

Gary Dymski | Home Work

October 26, 2000

Q. WE USE A wood-burning stove and our problem is a buildup of creosote in our brick chimney. The stove is cleaned often, every 2 to 3 weeks, but the buildup of creosote in the chimney creates sparks and this starts a fire in the chimney. We bought a commercial cleaner to spray on the wood. It is supposed to help retard the creosote buildup. Do you have any other suggestions? -Monika Ristau, Kings Park

A. The first thing to do is quit using the wood- burning stove until your brick chimney is thoroughly inspected. I doubt spraying your wood with a commercial cleaner will do much good. My guess is your creosote buildup or something else is restricting air flow through your chimney.

About 5,500 home fires occur every year because of problems with chimneys and fireplaces, according to the U.S. Consumer Products Safety Commission. Most of these fires can be prevented with the proper fireplace and chimney maintenance, which includes timely inspections and cleaning.

I suggest you have a reputable mason inspect your chimney for cracks in the flue or other defects that could be creating a venting problem. The accumulation of soot restricts the flow of air through the flue. A buildup in the flue walls of 1/4 inch to 1/2 inch of soot can restrict air flow by as much as 20 to 30 percent.

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Even if you've tackled the buildup of creosote, something else could be restricting the air flow. Chimneys attract birds and small rodents who are looking to build nests. Twigs, dry grass and leaves are often packed in the top of the chimney, again restricting air flow. This poor air flow can result in deadly carbon monoxide gas filling the living area instead of being vented out of the fireplace. Carbon monoxide reacts with hemoglobin in blood, reducing the body's capacity to distribute oxygen. In high concentrations, it can cause unconsciousness and death.

I've written quite a bit about fireplaces and chimneys over the last few years and can't stress enough the life-or-death importance of maintaining them properly. One of the best sources of information regarding fireplace and chimney maintenance is the Chimney Safety Institute of America (www.csia.org). Call 800-536-0118 or write the association at 8752 Robbins Rd., Indianapolis, Ind. 46268 for a list of certified chimney sweeps in your area.

The other possibility is a stove that is vented directly to an exterior wall rather than the through the chimney. Furnaces vented in this manner are the newer, high-efficiency models (usually as efficient as 95 percent).