Section 23 31 00 - HVAC Ducts and Casing - Part 1: General

Nov 4, 2026

Uploaded by Putri

DIVISION 23, Section 23 31 00 specifies HVAC ductwork and casing requirements for low- and high-velocity systems, covering furnishing, installation, and related accessories. It establishes one-year guarantee terms covering workmanship and performance issues such as noise, chatter, whistling, vibration, and pulsation-free operation. The section defines required submittals, including duct shop drawings and floor plans, and sets coordination steps before fabrication to match site conditions. Standards and codes governing materials, sealing methods, and compliance with SMACNA and NFPA 90A are included, along with duct material and construction guidance by pressure class.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages10

Reading Time25 min

AccessFree to download

PART 1: GENERAL

1.01 Work Included

1.02 Applicable Provisions

1.03 Guarantee

1.04 Submittals

1.05 Contractor Coordination

1.06 Standards and Codes

PART 2: PRODUCTS

2.01 Duct Material

2.02 Sealing of Seams and Joints

2.03 Low Pressure Ductwork (Less Than 3 Inches Static Pressure)

2.04 Medium Pressure Ductwork (3 Inches Through 6 Inches Static Pressure)

DIVISION 23 HEATING, VENTILATING AND AIR CONDITIONING Section 23 31 00 – HVAC Ducts and Casing PART 1: GENERAL 1.01 Work Included A. This section provides for furnishing and installing low velocity and high velocity ductwork and includes duct construction and accessories. 1.02 Applicable Provisions A. Refer to Section 23 00 00, Heating, Ventilating and Air Conditioning (HVAC) . 1.03 Guarantee A. Guarantee all ductwork for one year from the date of final acceptance. The guarantee will cover workmanship, noise, chatter, whistling, or vibration. Ductwork must be free from pulsation under all conditions of operation. Correct any and all defects that appear after the system is put in operation. Submit corrective measures to Architect for review prior to implementation. 1.04 Submittals A. Submit ductwork shop drawings, including ¼ inch per foot floor plans and equipment room plans. Refer to Section 23 00 00 for requirements. B. Submit oval duct reinforcing methods; submit casing and plenum shop drawings. 1.05 Contractor Coordination A. Erect all ducts in the general locations shown, but conform to all structural and finish conditions of the building. Before fabricating any ductwork, check the physical conditions atthe job site and make all necessary changes in cross sections, offsets, and similar items, whether they are specifically indicated or not. B. Refer to Section 23 00 00 for coordination requirements between ductwork and other trades. Especially careful coordination prior to commencement of any work will be required. 1.06 Standards and Codes A. Except as otherwise indicated, sheet metal ductwork material and installation shall comply with the latest edition of SMACNA HVAC Duct Construction Standards (SMACNA) for the appropriate pressure classification. All air distribution devices (such as dampers) included in this specification shall comply with latest edition SMACNA and NFPA 90A. PART 2: PRODUCTS 2.01 Duct Material A. Except for the special ducts specified elsewhere, use prime galvanized steel sheets or coilsup to 60 inches wide. Stencil each sheet with proper gage and manufacturer’s name. Stencil coils of sheet steel throughout on 10-foot centers with gage and manufacturer’s name. Contractor is cautioned that Engineer may random check duct and strap gauges with a micrometer to verify compliance with the specifications. 2.02 Sealing of Seams and Joints A. The entire duct system shall be sealed. Do not use oil solvent based sealants except where specifically allowed herein. Seal the seams and joints of ductwork and fittings by applying one layer of sealant, then immediately spanning the joint with a single layer of 3 inch wide open weave glass fiber tape, then apply sufficient additional sealant to completely embed the cloth. Thoroughly clean the duct areas to be sealed prior to application of tape and sealant. 2.03 Low Pressure Ductwork (Less Than 3 Inches Static Pressure) A. Ductwork downstream of terminal units and exhaust ductwork downstream of fans is defined as low pressure ductwork. B. Rectangular. Furnish rectangular low pressure ducts constructed of sheet metal with metal gages meeting or exceeding that required in latest edition SMACNA, heavy enough to withstand the physical abuse of installation, or in the following minimum gages: Largest Dimension U.S. Gage 12” and less No. 26 13” to 30” No. 24 31” to 54” No. 22 55” to 84” No. 20 85” and above No. 18 C. Round. Furnish round, low-pressure ducts which are spiral wound, such as manufactured by United McGill. Use the following gages for shop fabricated ducts: Diameter U.S. Gage D. Low Pressure Insulated Flexible Duct 1. Furnish factory-fabricated, flexible duct for connections between low velocity trunk ducts and supply air diffusers. 2. Furnish flexible duct with an airtight inner liner, insulation and outer jacket. Construct the inner liner of coated steel helix and fabric substantially bond

FAQs

What ductwork is included under Section 23 31 00?

The section covers furnishing and installing low-velocity and high-velocity ductwork, including duct construction and accessories.

What guarantee period applies to the ductwork?

All ductwork is guaranteed for one year from the date of final acceptance, covering workmanship and operational issues such as noise, vibration, and pulsation-free performance.

How must duct seams and joints be sealed?

The duct system must be fully sealed using an allowed sealant method: one sealant layer, then a single layer of 3-inch wide open weave glass fiber tape spanning the joint, followed by sufficient additional sealant to embed the cloth.

Nov 4, 2026

Uploaded by Putri