CHANTILLY, Va. — The Sheet Metal and Air Conditioning Contractors’ National Association (SMACNA), an organization dedicated to promoting quality and excellence in the sheet metal and air conditioning industry, announced the fourth edition of its “HVAC Duct Construction Standards – Metal and Flexible” is now available. Building on a history of duct construction standards nearly 100 years old, the fourth edition of the standard represents advancements in sheet metal duct fabrication and installation requirements.

The updated 416-page standard was revised to provide contractors, designers, and facility owners with the information they need to apply effective and efficient solutions to their projects. Highlights of the updates to this standard include:

  • Added information on spray and aerosolized duct sealants;
  • Added tables for spiral flat oval duct for positive and negative pressure applications;
  • Added options for internal supports for spiral flat oval duct;
  • Updated liner requirements to include non-fiberglass liner types;
  • Added information for lined round duct and spiral fittings;
  • Added details for hangers to better illustrate where hangers are required; and
  • Updated requirements for flex duct hanger spacing and hanger width, among other technical updates, that will enable the standard to be fully compliant with industry advancements in sheet metal for air distribution systems.


“The sheet metal and HVAC industry continues to evolve and adapt to new technologies, and those changes are reflected in this new edition of the HVAC Duct Construction Standards,” said Vince Sandusky, CEO, SMACNA. “We’ve provided best-in-class information that allows code officials, design professionals, and contractors to deliver safe, modern, and resource-efficient constructed duct systems.”

Technical standards and manuals developed by SMACNA members have worldwide acceptance by the construction and code community as well as local and national government agencies. SMACNA standards and manuals address all facets of the sheet metal and HVAC industry — including duct construction and installation, indoor air quality, energy recovery, roofing and architectural sheet metal, welding, and commissioning — and advancements are made possible by those in the industry who provide suggestions for improvement based on knowledge, experience, and research. Materials, including the latest edition of the “HVAC Duct Construction Standards – Metal and Flexible” standard, are available to order in book or PDF format via SMACNA’s online bookstore. For more information, visit