Sheet Metal and Air Conditioning Contractors' National Association
SMACNA duct construction
SMACNA guidance is the fabrication and installation reference for sheet metal: what gauge the duct should be for its pressure class, how seams and joints are made, how it is hung, and how leakage is measured.
Adoption varies by jurisdiction — confirm the edition your authority having jurisdiction enforces before you run a walk against it.
What it covers
- Gauge and reinforcement by pressure class
- Seam, joint and connection construction
- Hanger type and spacing
- Duct leakage testing methods
What the evidence looks like
- Hanger spacing photographed along a run, not at one convenient point.
- Leakage test recorded with the instrument reading in the shot.
- Flexible connections and transitions photographed before ceiling close-in.
Checklists that verify work against SMACNA duct construction
3 free checklists, each with the photo every item needs before it can be submitted.
HVAC Rough-inHVAC rough-in inspection checklistDuctwork, refrigerant lines, condensate and equipment setting before the walls and ceilings close8 items13 photosHVAC Pre-coverHVAC pre-cover inspection checklistThe above-ceiling walk before the grid and drywall close on ductwork and lines7 items11 photosHVAC FinalHVAC final inspection checklistGrilles, registers, balancing and controls verified before startup and turnover7 items9 photos
Common questions
- What is SMACNA duct construction?
- Sheet metal fabrication and installation — gauge, seams, hangers, leakage class. It is published by the Sheet Metal and Air Conditioning Contractors' National Association. SMACNA guidance is the fabrication and installation reference for sheet metal: what gauge the duct should be for its pressure class, how seams and joints are made, how it is hung, and how leakage is measured.
- What does SMACNA duct construction cover?
- Gauge and reinforcement by pressure class; Seam, joint and connection construction; Hanger type and spacing; Duct leakage testing methods.
- What does a field inspection against SMACNA duct construction look at?
- Hanger spacing photographed along a run, not at one convenient point. Leakage test recorded with the instrument reading in the shot. Flexible connections and transitions photographed before ceiling close-in.
- Which edition of SMACNA duct construction applies to my project?
- Adoption varies by jurisdiction — confirm the edition your authority having jurisdiction enforces before you run a walk against it.
- Which checklists verify work against SMACNA duct construction?
- 3 free checklists in the RTI library reference this family — each listed on this page with the photo evidence every item needs before it can be submitted.
A standard is only met if the evidence exists
RTI holds the submit button until every mandatory item is answered and the photos are attached, then chains the record so it can be proven untouched later.
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