In any HVAC system, ductwork acts as the lungs of the building—moving air where it's needed most. But the material used to construct that ductwork isn’t just a technical detail. It has a direct impact on performance, safety, compliance, and cost. For HVAC designers and engineers, choosing the right duct material can make or break a project.

One of the most common comparisons in commercial and industrial settings is plastic vs metal ductwork. Each has distinct advantages, limitations, and use cases. The right choice will depend on the environment, fire safety requirements, installation constraints, and long-term maintenance expectations.

As regulations tighten and project demands grow more complex, understanding the strengths of both materials is essential. Whether the goal is to meet hygiene standards, reduce installation time, or boost fire performance, selecting the best duct material for HVAC starts with informed decision-making.

In this guide, we’ll explore plastic and metal ductwork side by side, examine their pros and cons, and help you specify the most suitable system for your next project.

Overview of Plastic Ductwork

Plastic ductwork refers to ventilation systems made from materials like uPVC (unplasticised polyvinyl chloride), polypropylene, or sometimes polyethylene. These materials are commonly used in low to medium pressure HVAC applications, especially where metal ducting may degrade due to environmental factors.

Unlike metal systems, plastic ventilation ducts offer excellent resistance to corrosion and chemical exposure. This makes them ideal for settings where moisture, chemical vapours, or salt-laden air are present. For example, plastic ducting is often used in:

• Swimming pools and spas
• Chemical laboratories
• Food processing facilities
• Clean rooms and pharmaceutical sites
• Light industrial HVAC systems

Because plastic is non-metallic, it does not rust and requires less maintenance in humid or chemically active environments. It is also much lighter than galvanised steel, which can reduce structural loads and simplify installation—particularly in retrofit projects or overhead spaces.

Plastic ductwork is also typically more cost-effective than metal, especially for small to mid-size systems. However, it does have limitations in terms of fire performance and pressure resistance, which we’ll explore later.

For these reasons, plastic ducting has carved out a key role in modern HVAC, particularly in niche or specialist environments where corrosion control, hygiene, or weight reduction are top priorities.

Overview of Metal Ductwork

Metal ductwork is the standard choice for most commercial and industrial HVAC installations. It is typically made from galvanised steel, a material valued for its strength, durability, and regulatory compliance.

Galvanised steel ducting is coated with a protective layer of zinc, helping to reduce corrosion over time. It offers excellent fire resistance, making it suitable for use in fire-rated systems and large-scale buildings where compliance with BS 476 and other UK fire safety standards is essential.

The rigid structure of metal ducting also allows it to maintain shape and airflow over longer distances. It’s ideal for high-pressure systems, large HVAC installations, and environments where ductwork must meet stringent DW/144 standards for fabrication and performance.

However, metal ductwork does come with trade-offs:

• It is heavier than plastic ducting, requiring more labour and suspension systems like channel profiles to support it.
• In moist or chemically active environments, it can still suffer from corrosion if not properly protected.
• Installation tends to be more time-consuming and costly due to cutting, sealing, and fixing requirements.

Despite these factors, metal ducting remains the most robust option for demanding applications. Its fire resistance, long lifespan, and regulatory approval make it a trusted material for offices, hospitals, schools, data centres, and large commercial buildings.

To support metal installations, Doby Verrolec also offers a wide range of duct accessories and duct stiffeners designed for performance and compliance. For installation efficiency, explore our wire suspension systems.

Side-by-Side Comparison: Plastic vs Metal Ductwork

Choosing between plastic and metal ducting depends on your specific HVAC project needs. Each material brings different strengths to system performance, fire safety, and installation.

The table below offers a clear comparison across key factors:

Key Takeaways

• Plastic vs metal ventilation ducts offer very different installation experiences and performance profiles.
• If weight, corrosion resistance, or hygienic performance are priorities, plastic ductwork may be better suited.
• Where fire resistance, long-term durability, or structural rigidity matter most, metal ductwork, especially galvanised steel, remains the preferred option.
• In many cases, a hybrid approach using both materials across zones may provide the best value and compliance.

For support with choosing between plastic vs galvanised steel ducting, or to explore compatible accessories and fixings, browse our ducting components or contact our technical team.

Where Each Material Works Best

Understanding where each ducting material performs best helps ensure both compliance and cost-effectiveness in HVAC design. From corrosive environments to high-occupancy buildings, the choice between plastic and metal ducting can significantly impact long-term system performance.

Plastic Ducting Applications

Plastic ductwork, including uPVC and polypropylene, is ideal for:

• Swimming pools and leisure centres
  Resistant to chlorine vapours and constant moisture, making it a safe choice in high-humidity spaces.
• Commercial kitchens
  Offers excellent corrosion resistance against greasy air and chemical cleaning agents. Smooth internal surfaces help with hygiene and airflow.
• Chemical laboratories and clean rooms
  Suitable for venting corrosive fumes or sterile environments. Plastic air ducts help reduce contamination risk.
• Light industrial HVAC systems
  Particularly where weight savings, corrosion protection, or flexible configurations are required.

Metal Ducting Applications

Metal ductwork, especially galvanised steel ducting, is preferred for:

• Office buildings and commercial premises
  Offers robust performance, meets fire resistance standards, and integrates well with ceiling systems.
• Data centres
  High durability and low fire load make it ideal for cooling systems in mission-critical environments.
• Educational and healthcare facilities
  Commonly required by building regulations for fire resistance and structural integrity.
• Factories and warehouses
  Suitable for high-volume ventilation in large spaces. Can withstand higher airflow rates and mechanical stress.
• Large-scale HVAC installations
  Metal systems offer long-term value and compliance for complex or multi-storey applications.

For help designing ducting systems tailored to your sector, explore Doby Verrolec’s bespoke engineering services.

Installation and Maintenance Factors

Selecting the best duct material for HVAC involves more than performance alone. You must also consider installation complexity and ongoing maintenance in overall system lifecycle cost.

Installation: Speed, Handling, and Support

• Plastic ductwork is easier to handle and install due to its lightweight properties. uPVC and polypropylene components can often be cut and fitted on-site with basic tools, reducing labour time and installation costs.
• Metal ductwork, particularly galvanised steel ducting, requires more effort to transport, lift, and seal. Installation teams often need hoists or multiple operatives, especially on large-scale projects. However, once installed, it provides a robust and fire-safe infrastructure.

Sealing methods also differ. Plastic ducts are typically joined using solvent welding, gaskets, or mechanical fasteners, whereas metal ducts use flanges, rivets, and mastic sealants. Metal systems may require stiffeners or structural reinforcements in high-pressure applications.

Doby Verrolec supplies a comprehensive range of suspension systems, duct stiffeners, and access panels to streamline installation for both duct types:

• Duct Access Doors
• Duct Stiffener Profiles
• Channel Profiles & Suspension Systems

These accessories are engineered for quick fitting, strength, and compliance across plastic and metal ductwork.

Cleaning and Longevity

When it comes to cleaning and upkeep:

• Plastic ventilation ducts are smoother internally and more resistant to dirt and corrosion. This makes them easier to clean and maintain hygienically—ideal for labs, food environments, or healthcare HVAC.
• Metal ductwork tends to have a longer lifespan but may require more effort to clean and inspect over time, especially if internal coatings degrade or moisture ingress leads to corrosion.

Plastic ducts may be more prone to mechanical damage or UV degradation if exposed, whereas metal ducts offer greater mechanical strength and resistance to impact.

Ultimately, routine inspection and scheduled cleaning are essential for both materials to preserve air quality and energy efficiency.

Sustainability and Environmental Impact

As environmental performance becomes a key consideration in HVAC system design, understanding the sustainability profile of plastic vs metal ductwork is essential for specifiers and project managers.

Recyclability and Material Recovery

Metal ductwork, particularly galvanised steel ducting, scores highly in recyclability. Steel can be recovered and repurposed multiple times with minimal loss of material quality, making it a valuable choice for circular construction models. This aligns well with BREEAM and LEED criteria.

In contrast, plastic ductwork (often made from uPVC or polypropylene) is more challenging to recycle post-use. While uPVC can be recycled in controlled systems, it typically involves more complex sorting and lower rates of reuse. That said, some manufacturers now offer ducting made from partially recycled plastic content, which can reduce overall environmental burden.

Embodied Carbon and Transport

Manufacturing plastic ducting usually results in lower embodied carbon than metal, due to energy-efficient moulding techniques and lower raw material weights. Its lightweight ducting properties contribute to reduced emissions during transport. Especially beneficial for remote or high-volume installations.

However, this benefit can be offset if plastic systems need more frequent replacement or additional fire treatments to meet regulatory standards.

Longevity and Lifecycle Value

Durability is a crucial sustainability factor. Metal ductwork typically lasts longer under harsh conditions, withstanding mechanical wear and high temperatures. This reduces the frequency of replacement, repair, and associated material waste.

Plastic air ducts, while corrosion-resistant and lighter, may degrade faster in exposed or high-temperature environments, particularly if not UV-stabilised or protected with additional coatings.

Helping Specifiers Make Informed Choices

Both materials have environmental trade-offs. Decision-makers must weigh recyclability, transport efficiency, and system longevity when choosing the best duct material for HVAC in sustainable builds.

We support informed, eco-conscious decisions by offering both plastic-compatible accessories and high-grade galvanised steel systems. Our systems meet today’s energy, performance, and sustainability targets. This makes them the perfect choice for you, no matter what the project.

FAQ’s

Is plastic ducting better than metal?

Plastic is ideal for humid or corrosive environments, but metal performs better in fire safety and durability for large-scale systems.

Can plastic ductwork be used in commercial buildings?

Yes, plastic ducting can be used in commercial HVAC, especially where corrosion or hygiene is a concern, like kitchens or labs.

Which is more cost-effective: plastic or metal ducting?

Plastic ducting is generally more affordable to install, but metal may last longer in high-impact or fire-sensitive environments.

Is metal ducting fire rated?

Yes, metal ducting typically offers better fire resistance and can comply more easily with fire safety standards.

Choosing the Right Ductwork for Your Project

At Doby Verrolec, we understand that no two HVAC systems are the same. That’s why we provide precision-engineered solutions for both plastic and metal ductwork, including supporting components, fixings, and bespoke manufacturing services.

Key Factors to Consider When Choosing Ductwork:

• Fire safety requirements — metal offers built-in fire resistance; plastic may need treatment
• Corrosion exposure — plastic is more suitable in highly humid or chemically aggressive environments
• System weight and handling — plastic ductwork is lighter and easier to install
• Regulatory compliance — metal ducting aligns more easily with fire codes and DW/144 standards
• Hygiene and cleanability — plastic performs well in clean rooms and food-safe environments
• Longevity and lifecycle cost — galvanised steel ducting offers durability and longer service life
• Environmental impact — plastic may have lower transport emissions, but metal is more recyclable
• Installation time and complexity — plastic installs faster; metal may need more labour and fixings

Need help choosing the right ductwork system?
Speak to our experts for specification support. We’ll help ensure your system meets safety, performance, and compliance requirements from the outset.