The Environmental Protection Agency (EPA) identifies leaking chimneys as one of the potential sources of carbon monoxide inside homes and other buildings. Carbon monoxide is a colorless, odorless gas produced by the incomplete combustion of fuels. A damaged or leaking chimney can allow carbon monoxide, water vapor, and other combustion gases to enter the building structure surrounding the chimney. Because carbon monoxide can accumulate in enclosed areas, a leak high in the chimney can still pose a serious risk throughout the home. At lower concentrations, prolonged exposure to carbon monoxide can cause flu-like symptoms, while higher concentrations can be life-threatening without adequate warning. A properly maintained chimney liner helps keep combustion products from a fireplace, woodstove, furnace, or other fuel-burning appliance safely contained within the chimney as they travel upward and exit the building.
A leaking or damaged chimney can also increase the risk of a fire in the surrounding building structure. Cracked mortar, missing bricks, or damaged clay liner tiles can allow intense heat and even flames to escape the flue and enter the chimney structure, potentially reaching combustible materials within the surrounding walls, ceilings, or roof. This can result in serious property damage and put occupants at risk. A properly installed chimney liner helps reduce dangerous heat transfer by creating a protective barrier that contains hot gases and flames while providing insulation between the flue and the surrounding structure.
A properly insulated chimney liner can also help reduce creosote buildup along the inside walls of the flue. Creosote is a highly combustible substance and a major fuel source in chimney fires, which can severely damage the chimney and potentially spread to the surrounding building. Even when a chimney fire remains contained within the flue, the extreme heat can damage the liner and compromise the structural integrity of the chimney. If you know or suspect that a chimney fire has occurred, do not use your fireplace or other fuel-burning appliance until the chimney has been professionally inspected. A chimney liner helps minimize creosote buildup by keeping the flue warmer. By insulating the interior of the flue from the cooler surrounding chimney structure, the liner helps reduce condensation of moisture and creosote inside the flue, which can contribute to dangerous buildup and chimney fires.
You should have your chimney, chimney liner, flue, fireplace, and other fuel-burning appliances professionally cleaned and inspected at least once a year. If an inspection reveals damage inside the flue that compromises its ability to contain combustion gases or otherwise affects safe operation, you should have a new liner installed or the appropriate repairs completed before using the fuel-burning appliance again. Regular inspections and proper chimney maintenance can help protect your home, improve safety, and reduce the risk of costly chimney-related damage.