Technical Resources
Gauge charts, duct standards, and tools for HVAC and mechanical contractors.
Duct Gauge Reference Chart
Galvanized steel sheet gauge vs. thickness. Common application guidelines based on SMACNA standards.
| Gauge | Thickness (in) | Thickness (mm) | Common Application |
|---|---|---|---|
| 26 ga | 0.0187" | 0.48 mm | Residential dryer vents, light duct liners |
| 24 ga | 0.0239" | 0.61 mm | Residential and light commercial supply/return duct (Low pressure) |
| 22 ga | 0.0296" | 0.75 mm | Light commercial duct, medium pressure systems |
| 20 ga | 0.0359" | 0.91 mm | Commercial duct, medium-high pressure, exhaust systems |
| 18 ga | 0.0478" | 1.21 mm | High-pressure commercial duct, large rooftop systems |
| 16 ga | 0.0598" | 1.52 mm | Industrial exhaust, kitchen exhaust risers |
| 14 ga | 0.0747" | 1.90 mm | Heavy industrial applications, high-velocity systems |
| 12 ga | 0.1046" | 2.66 mm | Heavy industrial, grease exhaust (black iron equivalent) |
| 10 ga | 0.1345" | 3.42 mm | Extreme industrial, structural duct applications |
Gauge vs. thickness values per SMACNA HVAC Duct Construction Standards. Call the counter to confirm gauge availability for custom orders.
TDC vs. S&D — Quick Reference
The two most common rectangular duct connection systems in Ontario.
Roll-formed flange crimped onto the duct end. Sections connect with steel clips and a foam or rubber gasket. Airtight, demountable, and the Ontario commercial standard for medium and large systems.
When to use: Commercial HVAC, any system requiring SMACNA Class A or B leakage rating, high-pressure applications, large rectangular duct (> 18" on either side).
Slip connector slides over one duct end; a drive cleat locks the joint on the opposite side. Fast to install, lower material cost, no gasket required on residential-grade systems.
When to use: Residential HVAC, light commercial low-pressure systems, smaller rectangular duct (≤ 18" on both sides), budget-sensitive retrofits.
Welded or roll-formed angle iron flange, bolted connection. Used for large or industrial duct, high-pressure systems, and applications requiring demountable joints under load.
When to use: Industrial exhaust, large commercial systems, kitchen exhaust risers, any bolted joint application.
Free Tools for HVAC Contractors
Call the counter.
We quote custom fittings the same day. Galvanized, stainless, aluminum, and black iron, 28 to 10 gauge.