Noticed this crack on back wall while I was cleaning it out. My home is less than 5 years old but do use the fireplace quite often in the winter time. Help

Whether your masonry chimney is used to vent a fireplace, woodstove or furnace, most have sections of clay flue tile stacked one on top the other to form a liner called the flue.
The combustion process creates noxious gases that can contain creosote/soot, carbon monoxide and corrosive chemicals. The purpose of your chimney is to safely vent these hazardous flue gases from your home.
Flue tiles can crack due to “sudden occurrences” such as a previous chimney fire, lightning strike, or seismic event.
Years of exposure to corrosive chemicals and moisture from combustion can attack clay flue tiles, causing pieces of the flue liner to flake off or delaminate, a process called spalling.
Fire & Health Risks
