To review ductwork against SMACNA’s HVAC Duct Construction Standards, confirm the edition the specification and the adopted mechanical code name, then trace each duct system from its pressure class on the plans through the duct construction table or notes, the seal class, and the leakage testing scope to the specification sections that govern it. Flexible duct extent and support, reinforcement and hanger references, and fire and smoke damper installation details should point to the same documents and editions everywhere. AI can flag conflicts; the mechanical engineer of record and the authority having jurisdiction decide compliance.
What do SMACNA’s HVAC Duct Construction Standards cover?
SMACNA’s store page for HVAC Duct Construction Standards — Metal and Flexible describes the 4th edition as its flagship standard for sheet metal duct fabrication and installation requirements. Its table of contents runs from engineering and design, including the information required for duct construction, model specifications, and duct sealing, through rectangular duct construction and reinforcement, round, flat oval, and flexible duct, fittings, hangers and supports, exterior components, accessories such as volume dampers and duct liner, double-wall duct, casings and plenums, specialty systems, and functional criteria. It is a construction standard: it tells the fabricator and installer how a duct of a given pressure class is built, sealed, reinforced, and supported once the designer has assigned those classes on the documents. It does not size ducts, set fire-resistance ratings, or decide where dampers are required.
The store page lists the 4th edition with a publication year of 2020 and 416 pages, and names its significant changes as flat oval tables for positive and negative pressure, spray and aerosolized duct sealants, non-fiberglass duct liner, spiral duct fittings, duct hanger updates, and flexible duct hanger spacing and support bracing. SMACNA’s technical standards page says SMACNA is accredited by the American National Standards Institute, and UFGS 23 30 00 HVAC Air Distribution (Active, published February 1, 2025) cites the document as ANSI/SMACNA 006 (2020). Checked October 27, 2026. The edition that governs is the one the contract specification names and, where the adopted mechanical code references SMACNA documents, the one in that code’s referenced standards chapter with local amendments. A project manual written from an older master may still cite the 3rd edition, so record the edition each document actually names rather than assuming the 4th edition applies.
Two related SMACNA documents usually appear in the same specifications. The HVAC Air Duct Leakage Test Manual is described by SMACNA as the American National Standard ANSI/SMACNA 016-2012, second edition, covering leakage criteria, test procedures, test apparatus and setup, and recommendations on when to test. The Fire, Smoke and Radiation Damper Installation Guide for HVAC Systems is listed as the sixth edition, published in 2022, with updated ICC, UMC, and NFPA code references and information on damper inspection, testing, and servicing. UFGS 23 30 00 cites that guide as a 2022 edition but labels it the 5th edition, so confirm the edition number and year against the copy the project holds. Where duct materials, plenums, and dampers are required by code, see the IMC guide, the UMC guide, and the NFPA 90A guide; this page follows how the ductwork itself is classified, built, sealed, tested, and supported.
Gather every document that classifies or describes ductwork
Collect the mechanical general notes and legend, the duct construction and leakage testing table if the drawings carry one, duct plans with pressure class tags and the points where the class changes, the equipment schedules with fan static pressures, duct details for reinforcement, hangers, flexible duct connections, and access doors, fire, smoke, and combination damper schedules and details, the life safety plans showing rated walls, floors, shafts, and smoke barriers, and reflected ceiling plans where flexible runouts serve diffusers.
Add the air distribution or ductwork specification (UFGS 23 30 00 on federal work, or the project’s own metal duct section, which many project manuals number in the 23 31 00 range), the testing, adjusting, and balancing section, the duct insulation section, and the commissioning requirements. UFGS 23 30 00 assigns ductwork leak tests to Section 23 05 93, so a set that omits the TAB section is missing the test scope. Add the SMACNA documents the specifications cite, from copies you are licensed to upload.
Trace each duct system from pressure class to test
| Review question | Sources to compare | Decision to record |
|---|---|---|
| Editions cited | Mechanical general notes, air distribution specification, TAB specification, damper details | Record the edition of the duct construction standards, the leakage test manual, and the damper installation guide each document cites, and flag a mix of editions. |
| Pressure class assignment | Duct plans, duct construction table or notes, fan schedules, specification | Confirm every duct system has one pressure class in every source, that the plans mark where the class changes, and that the class is consistent with the scheduled fan pressure as the engineer intends. |
| Seal class | Duct construction table, general notes, specification sealing article | Check that the seal class or sealing requirement for each pressure class and location is stated once, the same way, and that sealant products in the specification suit it. |
| Leakage testing scope | Duct construction table, air distribution specification, TAB specification, commissioning plan | Confirm which systems and what portion of each are tested, under which test procedure, and who performs and witnesses it, with the same answer in every document. |
| Reinforcement, hangers, and construction references | Duct details, general notes, specification, structural attachment details | Check that details defer to the cited standard or show their own construction consistently, and that hanger attachments agree with the structural and seismic bracing documents. |
| Flexible duct extent and support | Duct plans, reflected ceiling plans, flexible duct details, specification | Flag flexible runouts drawn longer, routed through spaces, or supported differently than the specification and details allow, and plans that show flexible duct where the specification limits it. |
| Fire, smoke, and combination dampers | Damper schedule, life safety plans, duct plans, damper installation details, specification | Confirm each duct crossing a rated or smoke-resistant assembly has the scheduled damper type, an installation detail, and access, and that the details cite the edition of the installation guide the specification names. |
Damper ratings and opening protectives follow the IBC Chapter 7 guide, inspection and testing of fire dampers the NFPA 80 guide, smoke dampers in smoke barriers the NFPA 105 guide, and smoke control systems the NFPA 92 guide. Duct penetrations without dampers continue in the ASTM E814 and UL 1479 firestop guide. The air distribution specification itself is compared article by article in the HVAC air distribution specifications guide, leak testing and balancing in the TAB specifications guide, duct liner and wrap in the mechanical insulation guide, duct bracing in the mechanical seismic bracing guide, and DoD HVAC criteria in the UFC 3-410-01 guide.
Example: a supply main with two pressure classes and no test scope
Hypothetical example. A four-story office building uses rooftop air handlers with medium-pressure supply mains feeding VAV terminal units. The duct construction table on the mechanical legend sheet assigns the supply mains a higher pressure class than the duct plan tags on the third floor, the general notes name a different seal class than the specification’s sealing article, the air distribution specification sends leak testing to the TAB section, which is not in the issued set, flexible runouts on the reflected ceiling plan reach diffusers well beyond the length the specification allows, and the fire damper detail at a rated corridor wall cites an earlier edition of the damper installation guide than the specification.
The third-floor supply main is tagged with a lower pressure class on the duct plan than the duct construction table assigns, the general notes and the specification name different seal classes, leak testing is assigned to a TAB section that is not in the issued set, several flexible runouts exceed the length the specification allows, and the corridor fire damper detail cites a different damper installation guide edition than the specification. Confirm the pressure and seal classes, the leakage test scope, the flexible duct runs, and the damper guide edition, and coordinate the drawings and specifications.
The mechanical engineer confirms the intended pressure and seal classes, issues the TAB section or moves the test scope into the duct construction table, shortens or reroutes the flexible runouts, and aligns the damper detail with the specification. The finding is a conflict between documents, not a judgment of duct design or fabrication.
Review ductwork against SMACNA standards with Groundbook
Upload the current drawings and specifications to Groundbook, and state the edition, amendments, and review scope in your instructions. Add the SMACNA duct construction standards, leakage test manual, and damper installation guide editions the specifications cite, from copies you are licensed to use where the license permits uploading them, along with the adopted mechanical code and its amendments. See how Groundbook works with local and licensed codes.
Compare the mechanical general notes and legend, the duct construction and leakage testing table, duct plans with pressure class tags, fan and equipment schedules, duct, hanger, flexible duct, and damper details, the damper schedule, the life safety plans, the reflected ceiling plans, and the air distribution, metal duct, TAB, and duct insulation specifications. Flag SMACNA editions that differ between documents, duct systems with more than one pressure class or no class change marked, seal classes that disagree, leakage testing scope that is missing or assigned to a section not in the set, flexible duct drawn beyond what the specification allows, and duct crossings of rated or smoke barriers with no damper, no installation detail, or a detail citing another edition. Use the supplied SMACNA documents and cite both sources.
Groundbook links each potential finding to the sheets, schedules, and specification articles involved. It does not size ducts, select gauges or reinforcement, or calculate allowable leakage.
Document review does not certify duct construction, replace leakage testing, or approve damper installations, and it does not replace the mechanical engineer of record, the testing and balancing agency, or the authority having jurisdiction.