Technical Guide HVAC

HVAC Ductwork Fabrication: What Contractors Need to Know

January 22, 2025
9 min read
Ventilation rectangular ducts and pipeline parts on store outdoors.

For HVAC contractors throughout Georgia and South Carolina, the quality of ductwork fabrication directly impacts system performance, energy efficiency, and customer satisfaction. Understanding fabrication standards, material options, and quality indicators is essential for successful commercial installations.

Understanding HVAC Ductwork Fabrication

Custom HVAC ductwork fabrication involves precision metal forming to create rectangular and round duct sections, fittings, transitions, and specialty components. Unlike off-the-shelf products, custom fabrication allows HVAC contractors to:

  • Match exact building specifications and spatial constraints
  • Optimize airflow efficiency through properly sized components
  • Reduce installation time with pre-fabricated, ready-to-install sections
  • Accommodate complex mechanical room layouts and roof configurations

Material Selection for Ductwork

Galvanized Steel

The most common material for commercial HVAC ductwork, galvanized steel offers excellent durability, affordability, and corrosion resistance suitable for most applications.

Standard Gauge Options:

26 Gauge

Light-duty applications, smaller duct runs

24 Gauge

Standard commercial installations

22 Gauge

Heavy-duty, large duct systems

Stainless Steel

Required for specialized environments including commercial kitchens, laboratories, and corrosive atmospheres. Stainless steel ductwork resists moisture, chemicals, and high temperatures better than galvanized alternatives.

Aluminum

Lightweight and naturally corrosion-resistant, aluminum ductwork is ideal for coastal installations in Savannah, Charleston, Hilton Head, and other saltwater environments where galvanized steel may corrode faster.

Critical Fabrication Standards

Quality HVAC ductwork fabrication must meet industry standards to ensure proper system performance:

SMACNA Standards

The Sheet Metal and Air Conditioning Contractors' National Association (SMACNA) provides comprehensive fabrication standards covering construction classes, reinforcement requirements, and sealing methods. Professional fabricators follow SMACNA guidelines to ensure code compliance and system integrity.

Air Leakage Requirements

Modern building codes require low-leakage ductwork systems. Seal Class A and B requirements mandate specific sealing methods at joints, seams, and connections. Proper fabrication with tight-fitting joints minimizes air loss and maximizes system efficiency.

Dimensional Accuracy

Precise dimensions are critical for proper fitting and connection. Quality fabricators maintain tolerances of ±1/16" to ±1/8" depending on duct size, ensuring components fit together correctly without field modifications.

Essential Ductwork Components

Straight Sections

Standard rectangular or round duct runs in various sizes. Pre-fabricated sections reduce field labor and ensure consistent quality.

Transitions

Size and shape changes between duct sections. Smooth transitions minimize pressure loss and turbulence for efficient airflow.

Fittings & Elbows

Direction changes, tees, wyes, and offsets. Proper radius and turning vanes reduce pressure drop and noise.

Rooftop Curbs

Custom-fabricated curbs for rooftop HVAC units. Proper flashing integration prevents water intrusion.

Quality Indicators to Look For

When evaluating ductwork fabrication shops, HVAC contractors should assess these quality factors:

  • Clean, Burr-Free Edges

    Properly cut and deburred edges prevent air leakage and worker injury during installation.

  • Square Corners and True Dimensions

    Accurate bending and forming ensure proper connections without field adjustments.

  • Proper Reinforcement

    Tie rods, angles, and bracing as required by SMACNA based on duct size and pressure class.

  • Consistent Seam Quality

    Pittsburgh, snap-lock, or welded seams executed uniformly throughout production run.

Working with a Fabrication Partner

Successful HVAC installations depend on effective collaboration between contractors and fabricators:

Best Practices for Ordering Custom Ductwork

  1. Provide detailed drawings: CAD files or dimensioned sketches showing all sizes, fittings, and connections
  2. Specify material and gauge: Clearly indicate metal type and thickness based on application requirements
  3. Indicate reinforcement needs: Note pressure class and any special structural requirements
  4. Communicate timeline: Provide realistic schedule allowing adequate fabrication and delivery time
  5. Discuss installation access: Ensure fabricated sections can be transported and installed in available space

Regional Considerations for Coastal Georgia

HVAC contractors in coastal Georgia and South Carolina face unique environmental factors:

  • High Humidity: Proper sealing and insulation prevent condensation issues in ductwork
  • Salt Air Exposure: Coastal installations near Savannah, Hilton Head, and Charleston benefit from coated or aluminum ductwork
  • Extended Cooling Season: Systems run longer, requiring durable, well-sealed ductwork to maintain efficiency
  • Hurricane Considerations: Rooftop equipment and ductwork require secure mounting and reinforcement

Need Custom HVAC Ductwork Fabrication?

MPI Fabrication specializes in precision HVAC ductwork for contractors throughout coastal Georgia. SMACNA-compliant fabrication, fast turnaround, ES1-certified quality control.

MPI Fabrication: Your HVAC Ductwork Partner

At MPI Fabrication, we understand the demands HVAC contractors face. Our Richmond Hill facility serves installers throughout Savannah, Statesboro, Charleston, and the entire Southeast with:

24-72 Hour Turnaround: Fast production on standard ductwork orders
CAD Integration: Direct fabrication from your engineering drawings
SMACNA Compliant: All fabrication meets industry standards
ES1 Certified: Quality control on every project

Partner with MPI Fabrication for reliable, high-quality HVAC ductwork that helps you complete installations on time and to specification. Contact us today to discuss your next commercial HVAC project.