The Ontario Building Code | Separation of Flue Liners

9.21.4.9. Separation of Flue liners

(1) Flue liners in the same chimneyshall be separated by not less than 70 mm of masonry or concrete exclusive of liners where clay liners are used, or 90 mm of firebrick where firebrick liners are used.

(2) Flue liners referred to in Sentence (1) shall be installed to prevent significant lateral movement.