Code Library › Volume 1 › Section 9.33 — Heating and Air-Conditioning
PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code

9.33.6.5.Galvanized Steel or Aluminum Supply Ducts

(1) Galvanized steel or aluminum supply ducts shall conform to Table 9.33.6.5. (2) The design of fittings for ducts shall conform to ANSI/SMACNA 006, “HVAC Duct Construction Standards – Metal and Flexible,” except that metal thicknesses shall conform to Table 9.33.6.5. Table 9.33.6.5. Minimum Metal Thickness of Ducts Forming Part of Article 9.33.6.5. Minimum Metal Thickness, mm Maximum Maximum Width Type of Duct Duct Material Diameter, mm or Depth, mm Galvanized Steel Aluminum Round ducts serving single dwelling units 125 or less — 0.254 0.30 350 — 0.33 0.30 Round over 350 — 0.41 0.41 — 350 0.33 0.30 Rectangular, enclosed — over 350 0.41 0.41 Rectangular, not enclosed, with required clearance up to — 350 0.33 0.41 12 mm — over 350 0.41 0.48 Rectangular, not enclosed, with required clearance of — 350 0.41 0.41 more than 12 mm — over 350 0.48 0.48

This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.

← Previous9.33.6.4. Coverings, Linings and InsulationNext →9.33.6.6. Construction of Ducts and Plenums

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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.