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Flexible Vs. Metal Ductwork: Which One Will Better Work For You?

Since the 1980s, HVAC contractors no longer use metal ductwork as their primary duct material. Flex ductwork is the default type of ductwork in most houses, but that does not mean it promotes better airflow.  

The phrase “out of sight, out of mind” is apt whenever it comes to the ductwork system. When air ducts are hidden behind walls, and in the basement, it’s easy to overlook them. However, home and business owners need to understand the difference between flexible ductwork and metal ductwork to know which is best for their property. 

The purpose of this post is to aid you in choosing which is best for your home based on a comparison of metal and flexible ductwork. 

What is a metal duct?  

Metal ducts (also known as rigid or stiff ducts) can provide a more permanent solution to a commercial HVAC system. Spiral ducts are the most common or recognised type of metal ducts as they are popular in commercial HVAC ducting systems. Leading spiral duct suppliers explain they are popular because they are durable and can last for many years. This is especially true if they are routinely maintained. 

It involves the computerized design, measurement, and careful ductwork installation. HVAC experts evaluate the existing components of a commercial building—several factors to consider, including the furnace, heat pump, air conditioner, etc.  

A crucial factor to consider in a commercial building is the width-to-height ratio. There should be room for metal ducts to maximize performance and energy efficiency.  

What is a flexible duct? 

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A flexible duct is a component of an air conditioning system. Heating and cooling system ductwork are connected to air distribution with flexible ducting. These are mounted in the ceiling or walls as grills and registers in commercial buildings. 

Flexible ductwork is convenient for attaching supply air outlets to more rigid sheet metal ductwork. Usually, it is connected with long zip ties or metal band clamps.  

Flexible ductwork material types include rubber, PVC, stainless steel, silicone, polyurethane, and neoprene-dipped polyester fabric.  

The best materials for commercial buildings in extreme climates are rubber, PVC, stainless steel, and silicone. Due to its inherent resistance to heat and cooling, this ensures long-term productivity. The best abrasion resistance is found in rubber and polyurethane. 

When exposed to extreme weather conditions, silicon cannot withstand damage to its interior. Nevertheless, silicon and PVC offer the highest quality for air handling applications. This is because they are both flexible for any heavy-duty hose.  

The design of HVAC systems 

Branches of your HVAC system should be connected to flexible ducts rather than the main plenum. These ducts run throughout the building and supply air to individual ceiling vents. Various flexible duct materials are available to adapt to a building’s shape, such as rubber, stainless steel, silicone, and polyurethane. 

The primary difference between flexible ductwork and metal ductwork is the material. The rigid construction of metal ducts makes them suitable as the main pillar of trunk-and-branch ductwork. Their direct connections to furnaces allow them to supply air to various flexible branches. 

The installation processes 

The main difference between flexible and metal ductwork is that flexible ducts are often easier to install. The material is flexible and lightweight, bending to conform to the heating or cooling system. The installation process is much faster, reducing your company’s labor costs and downtime. 

Whereas, metal ductwork requires meticulous installation. To fit into a building’s dimensions, sheet metal needs precise measurements. Additionally, the rigid material is more difficult to transport and place in the right place. Due to this, metal ductwork installation is much more expensive. 

Air Resistance 

Flexible ductwork has the disadvantage that it has a higher resistance to airflow. Flexible ducts tend to crumple in a way that makes it more difficult for supply air to reach its designated ceiling vent than metal ducts. In the hands of a less experienced contractor, flexible ducts may be arranged in awkward configurations with sharp turns and sections that sag under their weight. 

Although metal ducts are more expensive, they are well worth the investment. They are flexible and have low air resistance. Using metal ductwork can reduce energy bills because the furnace and AC unit won’t have to work as hard to distribute air throughout the building. 


In addition to restraining airflow, flexible ductwork is more susceptible to poor installation. Many factors can go wrong, such as a poorly sealed joint, an excessive length lacking support, and crumpled sections. This type of material is, in fact, not as durable as sheet metal. An HVAC professional should perform more frequent maintenance on flex duct systems. 

The durability of metal ducts makes them a better long-term investment. Even though it is expensive, metal ductwork requires very little maintenance and is resistant to extreme temperatures. Sheet metal is, therefore, the most economical material in terms of energy usage. 


No matter what kind of ductwork you have in your building, you need to maintain it regularly if you want it to operate efficiently. It’s time to schedule an inspection with the HVAC contractors if you can’t remember the last time your building’s ductwork was assessed. Spending a little on maintenance now will save you a lot of money in the long run. 

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