The Ontario Building Code | Masonry or Concrete Chimneys
184.108.40.206. masonry or Concrete Chimneys
(1) Rectangular masonry or concrete chimneysnot more than 12 m in height shall conform to Part 9 if they serve,
(a) appliances with a combined total rated heat output of 120 kW or less, or
(2) masonry or concrete chimneys other than those described in Sentence (1) shall be designed and installed in conformance with the appropriate requirements in nfpa 211, "Chimneys, fireplaces, Vents and Solid Fuel-Burning Appliances".