Flue lining systems shall comply with one of the following:
- Clay flue lining complying with the requirements of ASTM C315.
- Listed and labeled chimney lining systems complying with UL 1777.
- Factory-built chimneys or chimney units listed for installation within masonry chimneys.
- Other approved materials that will resist corrosion, erosion, softening or cracking from flue gases and condensate at temperatures up to 1,800°F (982°C).