What gauge metal for residential duct?

26-28 gauge for most residential trunk lines, 30 gauge for small branch runs.

Round or rectangular?

Round is more efficient for airflow; rectangular fits better in tight joist cavities.

Rigid DuctworkGenerating image…

HVAC & Ventilation

Ductwork

Budget: $3-$8/ft (round pipe) | Mid-range: $8-$15/ft (rectangular) | Premium: $15-$25/ft (insulated or specialty)

Rigid Ductwork: Metal HVAC Duct Systems for Efficient Airflow (2026)

Prepared by Lumberama's Building Materials Team

|Last updated May 25, 2026|Sources & methodology

Rigid ductwork is the standard for HVAC air distribution, offering superior airflow and durability compared to flexible alternatives. Made from galvanized steel, it comes in round, rectangular, and oval profiles. Rigid duct is the preferred choice for main trunk lines and long runs.

Key Features

Superior airflow with smooth interior; Galvanized steel resists corrosion; Available in round and rectangular profiles; Long lifespan of 20-30 years; Fire-resistant construction

Specifications

Material: 26-30 gauge galvanized steel | Round diameters: 4"-24" | Rectangular: custom sizes | Length: 2-5 ft sections | Joints: snap-lock or S-drive

Applications

Main HVAC trunk lines; Supply and return air distribution; Commercial and residential systems; High-velocity HVAC systems; Kitchen exhaust runs

Installation Overview

Measure and cut duct sections to length. Connect using drive cleats, S-locks, or snap-lock joints. Seal all joints with mastic and foil tape. Support with metal hangers every 8-10 feet. Insulate ducts in unconditioned spaces.

Pros & Cons

Pros

✓ Best airflow efficiency; Very durable and long-lasting; Fire-resistant; Easy to clean and maintain

Cons

✗ More expensive than flex duct; Harder to install in tight spaces; Requires sheet metal tools; Can transmit noise

Top Brands

Master Flow

Speedi-Products

Southwark Metal

Code Requirements

Must meet IRC M1601 and SMACNA standards. Joints must be mechanically fastened and sealed. Support intervals per code. Fire dampers required at rated walls.

Buying Tips

Use round duct where possible for better airflow efficiency; Buy fittings (elbows, tees, reducers) at the same time to ensure compatibility; Invest in a good pair of aviation snips for clean cuts