Sheet Metal Ductwork Fabrication Guide

Views: 6     Author: Site Editor     Publish Time: 2023-06-06      Origin: Site

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Metal ductwork is more than just a minor cog in your HVAC units. It's the beholder of efficiency, filtering out contaminants, distributing air flow and cutting off noise. But what goes on during the fabrication process? Read on as we start with the key steps, from the chopping and formation to assemblies!

sheet metal ductwork

Step 1 – material selection

You need the right material for the sheet metal ductwork to guarantee durability and efficiency. Below are the factors to keep in mind.

Picking the right gauge

The gauge's appropriateness will depend on your HVAC unit's particular requirements. Remember, having a thicker gauge means greater strength. Where else, thinner ones offer flexibility at minimal costs. Yet it's ideal for balancing strength and weight to attain optimal performance.

The type of the sheet metal

Be it galvanized, stainless steel or aluminum, they all come with different rates of rust resistance and longevity. So whichever you pick, you have to consider the intended conditions where it will be deployed. On most occasions, galvanized steel is considered the most effective.

Step 2 cutting and formation

Precise metal ductwork formation and cutting are key to getting the required ductwork. Again, it follows the steps below.

Layering out and measurements

Measurements should be obtained carefully with the help of tape measures, rulers and markers. This will ensure a proper fit with fewer errors during assembly.

Cutting methods

CNC cutting machine, powered shears or snip could be used for cutting. Yet you have to follow the manufacturer's guidelines for safety. Powered shears will give straight cuts, snips for curves or irregulars, while CNC gives precision for complex patterns.

Forming techniques

Sheet metal is easygoing with different shapes so long as the formation uses equipment such as rollers, brakes and presses. The sheet metal for ductwork has to be formed in straight patterns, elbowed patterns and transitions so that the HVAC designs can accommodate it. Typically, brakes will give straight bends while the roller and the press are fit for curves.

Step 3 -  Joining and Sealing

This step is crucial for preventing air from leaking and ensuring optimal ductwork performance. 

Assembling techniques

In this process, you may use the Pittsburgh seam, the snapping lock or the flanged linking. You must ensure an alignment and a perfectly tight fit to prevent leakages.


You need a sealant, especially on the joints and the seams. This is done to prevent leakage and guarantees energy efficiency. Yet the sealant has to be compatible with sheet metal and resistant to temperature fluctuations.


Reinforcing involves spot welding or riveting to keep the critical points of the ductwork strong with fewer vibrations and distortion. In short, it means super integrity of the joints and transitions of the ductwork.

Quality control and set-up

You have to see through that the fabricated ductwork is of high quality and installed correctly. Here is the guideline.


Examine if there are any defects in the fabricated ductwork. These are normally in the form of sharp edges, denting and misalignment. You should ensure they are fixed before installing as they may cause leakages and damage the HVAC unit's integrity.


You have got to follow the manufacturer's guidelines or the so-called industry best practices when setting up the ductwork. Careful placement, sufficient support and secure connections are ideal. But adhering to the installation guidelines means better integrity and minimized strains and stress.


After installation, test the airflow and balancing to see if it operates efficiently. You can adjust the dampers and register until you get the desired airflow in each area.


So that's it about sheet metal ductwork fabrication. The precise cutting and forming. Joining, sealing, observing quality control regulations installing, and testing are all handiwork. And at times, you may require professional assistance if you are new to the industry.

Each step has a vital role, and a mishap affects the entire endeavor. This is too much to handle, while you can get fabricated sheet metal duct work from VASUCC.

And still, if you insist on DIY fabrication, they have a section of a variety of sheet metal on sale. And with a work history of decades in the sheet metal industry, you can trust you are in experienced hands.