Definition
Flue Liner
The inner lining of a chimney that contains combustion gases and protects the chimney structure from heat and corrosion.
The Full Picture
A flue liner is the conduit inside a chimney that safely channels combustion gases from a fireplace, furnace, or water heater to the outside. Liners come in three types: clay tile (most common in older homes, installed during original construction), stainless steel (used for relining or new installations), and cast-in-place (a cement-like mixture poured inside the existing chimney). The liner protects the chimney masonry from heat and acidic combustion byproducts, prevents carbon monoxide from leaking through mortar joints into living spaces, and ensures proper draft for combustion equipment.
Why It Matters
Why field professionals need to document this
A damaged or deteriorating flue liner is a serious safety hazard — it can allow carbon monoxide to enter living spaces and heat to transfer to combustible framing. Level II chimney inspections with camera footage routinely reveal cracked tiles, gaps between sections, and deteriorating mortar that are invisible from the firebox opening. Documenting liner condition with specific locations and measurements is critical for safety recommendations and insurance purposes.
In a Report
How this shows up in findings
Here's how a flue liner finding looks in a professional field report generated by ReportWalk:
Clay tile liner: cracked at 12 and 18 feet, gaps exceed 1/4" — stainless steel reline recommended
Stainless steel liner: intact, no corrosion, proper connection at appliance — passes inspection
Unlined chimney — pre-1940s construction, no liner present, not safe for use until lined
Relevant For
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