Chimneys are constructed of multiple masonry materials giving it much thickness. The passage way that conveys flue gases and excess heat is called a flue. This flue is the part of the chimney that needs sweeping to remove excess creosote from the system. Creosote is the flammable by-product of incomplete combustion that adheres itself to the walls of the flue. If the flue is unswept and has this build up, it can cause a chimney fire. After a chimney fire has occurred, it will require an inspection and possible RELINING. RELINING removes the bad terra cotta tile flue and replaces it with a stainless steel liner to create a sound chimney venting system.