How to fight, avoid chimney fires

NORTH CANAAN — The Canaan Fire Company and North Canaan Ambulance Corps volunteers responded Dec. 1 to the second chimney fire in town this fall. The first was in early November at a Granite Avenue home. The second was midday Saturday, when emergency personnel were dispatched to 20 Church Terrace. Fire Chief Lee Baldwin reported about an hour later that the fire — in a fireplace chimney at the back of a single-story extension — was under control.Both homes were saved, but it was a potentially dangerous way to get a chimney cleaning.Chimney experts agree that there is only one cause of a fire in a properly installed chimney: creosote. An annual cleaning should do the trick, if a fireplace or wood stove is used regularly.Creosote is a byproduct of burning wood. As smoke rises up the chimney flue, it cools quickly. The resulting condensation clings to the chimney’s interior walls. The highly flammable residue accumulates — faster when unseasoned or soft wood is burned, when wood is burned at low temperatures and when the airflow is restricted. As creosote builds up, it becomes more and more susceptible to being ignited by hot gas or a spark.Chimney fires are sometimes detected by a rumbling sound similar to that of an approaching train. It is not unusual for a passerby to call 911 for excessive smoke or flames shooting out of a chimney.Whether or not a chimney fire spreads to the attached home or building depends on many things, including a timely emergency response and the condition of the chimney.The blaze can easily spread through cracks in mortar or other damage, which can occur with time or can be caused by a previous chimney fire. It is possible for a fire to go undetected. A homeowner may be unaware that a fire has burned hot enough to melt mortar, crack tile and collapse the flue liner. Those breaches create pathways for the next fire to spread to the home. The same is true for a prefabricated metal chimney, required by building code in most places in the United States. Those flues have seams and other features that can be weakened by a fire, and should be replaced if one occurs. How to handle a fire In the event of a chimney fire:•Get everyone out of the house and call 911. • If possible, without putting oneself at risk, place a chimney fire extinguisher into the fireplace or wood stove. Extinguishers are inexpensive and indispensable; they produce heavy smoke that replaces the oxygen in the chimney and should smother the fire.• Close all air inlets.• Use a garden hose to spray down the roof (not the chimney).• Call a certified chimney sweep as soon as possible, and before burning again. Most homeowners insurance policies will cover repair costs. How to avoid a fire The Chimney Safety Institute of America (CSIA) offers simple guidelines for preventing fires.• When using a woodstove or fireplace it is essential to use seasoned or dry wood. Green wood, whether soft or hard, burns cooler because of the water trapped in its cells.• Build smaller fires that will burn hotter and completely, rather than large, slow-burning fires of packed wood. • Maintain an adequate air supply by opening the damper fully and not completely closing glass doors.The goal is to produce hotter, faster-moving smoke that spends as little time as possible in the chimney condensing and turning into creosote.• Never burn cardboard boxes, wrapping paper, trash, Christmas trees or anything likely to produce sparks.• On wood stoves, install stove pipe thermometers, and monitor temperatures when in use so burning practices can be adjusted as needed to burn at optimum temperatures.• Of course, have the chimney cleaned regularly. A cleaning should also include an inspection. Look for a CSIA certified chimney sweep.Discuss with the sweep how a fireplace or stove is used and follow any recommendations.A trained sweep and an informed homeowner will also be able to tell if a chimney fire has occurred. Signs include “puffy” creosote with rainbow streaks, warped metal, tile damage and a discolored or distorted rain cap.Creosote flakes or chunks might be found on the roof or ground. Roofing material can show damage from hot creosote. Smoke that seeps from the sides of the chimney is evidence of cracked masonry joints or liners.