With proper chimney care, chimney fires are completely preventable. Most people don't know if they need to have their chimney cleaned. We recommend cleaning when you have just moved into a home, as you don't know the cleaning or use history of the chimney. Otherwise, a cleaning is needed if there is a creosote build-up. Creosote is formed when the substances given off from wood exit the fireplace or wood stove. As these substances flow up into the relatively cooler chimney, condensation occurs. The resulting creosote residue is highly flammable. Certain conditions encourage the build-up of creosote such as a restricted air supply, unseasoned wood, lower temperature fires, and a cooler-than-normal chimney. If you are uncertain as to whether you need a cleaning, and have used it more than just a few times, then to err on the side of safety, have the chimney checked annually.