Chimney liners become cracked either by the house settling or from a chimney fire. Chimney fires are extremely hot fires that will almost certainly cause the chimney liner to crack. Once the tiles are cracked on a woodstove or fireplace chimney they can no longer be used. Using a fireplace or woodstove with a cracked chimney liner can cause a house fire.

The chimney liner is a terra cotta flue tile that lines the chimney to protect the structure from the heat generated in normal burning or a chimney fire. Each flue tile is 24 inches in length and is stacked one on top of each other within the chimney cavity using mortar between the joints.

If there is a cracked liner there are two options available. One is tear down the chimney to gain access for replacing the cracked chimney liner. In most cases this is impractical. The second alternative is to repair the chimney by installing a steel liner insert.

The steel liner insert is a dual wall constructed assembly that fits in the chimney cavity. It's placed down the entire length of the chimney sealing off the liner. It can be done in just a few hours and does not require disassembling the chimney.

If you have had a chimney fire it is very likely that you have a cracked flue liner. Check the flue liner for cracks using a strong light. It you cannot check the chimney yourself hire a chimney sweep to check it for cracks. If any cracks are found in the liner don't use the fireplace or woodstove until it is repaired.

Repairing the chimney by installing a steel liner can be expensive but it beats the alternative of disassembling the chimney to replace cracked liners. The steel liner is simply dropped into the flue creating a whole new flue system.

If you have a cracked chimney liner, consult a professional. Installing a steel chimney liner is very quick. It only takes a few hours to install the steel liner and it will last for decades.