The Ontario Building Code | Connections and Openings in Air Duct Systems
6.2.3.3. Connections and openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings in Air Duct Systems
(1) Air duct systems shall have,
(a) tight-fitting connections throughout, and
(b) no openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings other than those required for proper operation, inspection and maintenance of the system.
(2) Access openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings shall be provided in duct systems to allow the removal of material that may accumulate in plenums and ducts.