The Ontario Building Code | Clearance from Combustible Materials
22.214.171.124. Clearance from Combustible Materials
(1) The clearance between masonry or concrete chimneys and combustible framing material shall be not less than,
(a) 50 mm for interior chimneys, and
(b) 12 mm for exterior chimneys.
(2) A clearance of not less than 150 mm shall be provided between a cleanout opening and combustible material.
(3) Combustible flooring="http://thehandyforce.com/flooring/" title ="Handyman flooring install Toronto">flooring, subflooring="http://thehandyforce.com/flooring/" title ="Handyman flooring install Toronto">flooring and ceiling finishes shall have not less than a 12 mm clearance from masonry or concrete chimneys.