A flue lining in a masonry chimney is defined as "A clay, ceramic, or metal conduit installed inside of a chimney, intended to contain the combustion products, direct them to the outside atmosphere, and protect the chimney walls from heat and corrosion."
Although building codes vary from one state or locality to another, the installation of flue lining has been recommended since the early part of this century, and indeed most fire codes now mandate liners.
In the 1940's and again in the 1980's, masonry chimneys were tested by the National Bureau or Standards for durability due to rising concerns about their performance and safety. The tests revealed that unlined chimneys were so unsafe that researchers characterized building a chimney without a liner as "little less than criminal".
Chimney liners serve three main functions:
Types of chimney liners:
Considering the dangers of old unlined or damaged chimneys, and the many cost effective options now available to make these chimneys safe components of the home heating system, we encourage you to have your chimney professionally inspected by a local CSIA Certified Chimney Sweep an an annual basis to be sure it meets modern safety standards.