In many commercial and industrial HVAC projects, ductwork plays a critical role—but is frequently treated as an afterthought. While much focus goes into equipment selection and control systems, it’s the ductwork that delivers conditioned air to occupied spaces. Poorly installed ducting can undermine even the most advanced HVAC system, leading to air leakage, pressure imbalances, high energy bills, and inconsistent occupant comfort.

Proper ductwork installation is essential for achieving efficient airflow, meeting performance targets, and ensuring the long-term reliability of the system. From airflow optimisation and acoustic control to compliance with fire safety and building regulations, getting the ducting right from the start is key to overall system success.

This guide will explore everything from planning and materials selection to installation techniques, common pitfalls, and compliance testing. You’ll gain practical insight into best practices for efficient HVAC ductwork installation—whether you’re fitting out a new commercial building or retrofitting an existing system.

At Doby Verrolec, we understand the pressures HVAC professionals face on site. That’s why our engineered ducting systems, supports, and accessories are designed not only for performance but also for ease of installation, long-term hygiene, and code compliance. Let’s explore how a smarter approach to ductwork installation sets the foundation for high-performing HVAC systems.

Overview of the Ductwork Installation Process

The installation of ductwork in a commercial or industrial HVAC system involves several critical phases, each contributing to the overall performance, safety, and efficiency of the system. Understanding how to install ductwork properly from the outset ensures smooth project delivery and long-term reliability.

Here’s a high-level breakdown of the typical ductwork installation process:

1. Design and Planning

Before any materials are cut or ducts are fitted, thorough planning is essential. This stage involves:

• Reviewing mechanical services drawings
• Coordinating with other building systems (electrical, plumbing, fire safety)
• Determining routes for supply and return ducts
• Specifying airflow requirements and pressure losses
  Accurate planning helps prevent costly rework, spatial clashes, and inefficient layouts.

2. Material Selection

Choosing the right duct materials is vital for durability and compliance. Options include:

• Galvanised steel for general ventilation
• Aluminium for lightweight or corrosion-resistant applications
• Pre-insulated panels for thermal efficiency. Additional components like fire-rated ducting, access panels, and fixings must also be selected based on system requirements and regulations.

3. Pre-Fabrication

Where possible, ductwork sections are pre-fabricated off-site to save time, ensure consistency, and reduce site labour. Pre-fabrication allows for:

• Accurate dimensions
• Factory-sealed joints
• Integration of access panels or dampers. This approach supports faster and cleaner on-site assembly.

4. On-Site Installation

This phase includes:

• Marking routes and hanger positions
• Installing duct hangers and brackets
• Assembling duct sections
• Ensuring alignment and spacing. It’s crucial to follow the ductwork layout plan closely and avoid unsupported spans or kinks that could impair airflow.

5. Sealing and Insulation

To prevent energy loss and maintain air quality:

• All joints are sealed using approved tapes or mastic
• Ducts are insulated where required to reduce heat gain/loss and prevent condensation. Proper sealing also minimises air leakage and meets regulatory standards like Part L.

6. Testing and Commissioning

Once installation is complete, the system undergoes:

• Duct leakage tests
• Pressure and airflow balancing
• Smoke or tracer gas testing (if required). This final step verifies that the ductwork meets design intent and performs efficiently in operation.

Mastering the full ductwork installation process—from concept to commissioning—is key to building reliable, compliant, and high-performance HVAC systems.

Tools, Materials, and Components Used in Duct Installation

Installing ductwork efficiently and to a high standard requires the right tools, materials, and supporting components. Whether working on a new build or retrofitting an existing system, proper preparation makes a significant difference in performance, durability, and compliance.

Essential Tools for Duct Installation

HVAC engineers and installers rely on a core set of tools to fabricate, install, and seal ductwork systems. Common tools include:

• Tin snips and shears – for cutting sheet metal accurately
• Duct crimpers and seamers – for preparing duct ends and ensuring tight connections
• Cordless drills and riveters – for joining sections securely
• Sealant and foil tape – for air-tight sealing of joints and seams
• Duct lifters or hoists – to manoeuvre larger sections safely on-site
• Laser levels and plumb bobs – for accurate alignment during mounting
• Inspection mirrors and cameras – to check inside ducts and verify clean joins

Having the correct tools ensures a safer, faster installation process while helping avoid common issues such as misalignment or inadequate sealing.

Common Duct Materials

Selecting the right material for your HVAC ductwork installation depends on the environment, performance requirements, and fire safety standards:

• Galvanised steel – durable and widely used in commercial buildings for supply and extract ventilation
• Aluminium – lightweight and corrosion-resistant, suitable for specific applications
• Pre-insulated duct panels – combining structure and insulation in one, ideal for reducing energy loss and installation time
• Flexible ducting – used sparingly for short connections, though best avoided as a main ducting solution due to airflow inefficiencies

Each material type should be compatible with its application and compliant with applicable standards and specifications.

Key Components for a Reliable Duct Installation

Beyond duct runs themselves, the supporting components used in the installation process play a critical role in performance, hygiene, and safety. Quality matters.

1. Fire-Rated Ducts

Fire-rated ductwork helps compartmentalise fire and smoke in the event of an emergency. For example, kitchen extract ducts and ducts running between fire zones must comply with building fire safety regulations.

2. Access Panels

Access panels allow easy inspection, cleaning, and maintenance of duct systems. Strategically placed, they support long-term system hygiene and regulatory compliance.

3. Duct Hangers and Brackets

Secure support systems prevent sagging, misalignment, and vibration. Using pre-tested, easy-to-install support brackets ensures load-bearing stability and clean finishes.

4. Fixings and Fasteners

The right fixings ensure air-tight joints and long-term durability. This includes:

• Gasketed flanges
• Self-drilling screws
• Pre-punched cleats
• Slide-on connectors - Our ductwork accessories range includes these essential components, manufactured to precise tolerances.

5. Sealing and Insulation Products

Effective air sealing is essential for energy efficiency. Use:

• Low-permeability duct sealants
• Reinforced aluminium foil tapes
• External duct wraps for thermal insulation

These reduce heat loss and help meet Part L requirements of the Building Regulations.

Quality Components = Quality Installation

Using well-designed, durable components not only speeds up installation but reduces the risk of future system failures or compliance breaches. Doby Verrolec’s full portfolio of high-performance ducting solutions supports HVAC contractors and specifiers seeking long-term reliability and ease of installation.

From sheet metal systems to integrated access and bracket solutions, each product is engineered to help installers build safer, more efficient air distribution systems.

Step-by-Step Guide to Installing Ductwork

Professional HVAC installation demands precision, coordination, and high-performance components. Whether you’re managing a new commercial build or upgrading an existing system, following a structured process ensures compliance, system longevity, and efficient airflow.

1. Reviewing Design Drawings and Coordination Plans

Before installation begins, review all mechanical services drawings and BIM models.

• Confirm routing, access, and coordination with other services (electrical, sprinkler, BMS).
• Cross-check that duct dimensions align with available space and performance requirements.
• Ensure that fire-rated zones are clearly marked for correct component selection.

Doby Verrolec products such as fire-rated ductwork and access panels are designed to meet building regulations while supporting flexible integration into complex mechanical systems.

2. Marking Out Duct Routes On-Site

Accurate site marking is critical for a smooth install:

• Use laser levels and chalk lines to map out duct runs.
• Factor in clearances for maintenance and access (especially where duct access panels are used).
• Identify load-bearing surfaces for duct support points.

This planning stage also ensures enough space for brackets and supports, particularly when working with large or multi-branch systems.

3. Installing Hangers and Duct Supports

Support systems must maintain structural integrity over time:

• Use pre-galvanised, load-rated duct hangers and brackets.
• Position supports according to SMACNA or DW144 guidelines to prevent sagging.
• Include vibration isolation where needed.

4. Assembling, Connecting and Sealing Duct Sections

Precision assembly prevents air leakage and pressure loss:

• Align duct sections correctly using slip joints or flange systems.
• Apply mastic sealant or foil tape to all joints.
• Use gasketed flanges and fixings to maintain airtightness and reduce site labour.

Doby’s flange systems, including the DobyGrip® range, are proven in high-performance commercial applications and help deliver clean, professional finishes.

5. Applying Insulation Where Required

Thermal and acoustic insulation is vital for comfort and efficiency:

• Use external insulation wraps or pre-insulated duct panels where appropriate.
• Avoid compressing insulation during installation — this reduces its effectiveness.
• Fire-rated zones may require non-combustible insulation materials.

6. Ensuring Clearance, Access and Fire Safety

Final layout checks prevent operational issues:

• Verify all ducts have enough space for airflow and maintenance access.
• Install access doors and panels at strategic points — especially near dampers, AHUs, and change-of-direction points.
• Confirm compliance with compartmentation rules and fire safety standards.

Misaligned ductwork, inaccessible fittings or blocked fire dampers can result in costly rework or non-compliance at sign-off.

Common Installation Pitfalls to Avoid

Even experienced installers can encounter avoidable errors. Watch out for:

• Sagging duct runs – caused by poor bracket spacing or undersized supports.
• Misaligned connections – leading to air leakage and inefficient flow.
• Overuse of flexible ducting – which increases resistance and reduces airflow.
• Incorrect supply vs return placement – affecting thermal balance and IAQ.

Best Practices for Efficient HVAC Duct Installation

Efficient HVAC duct installation is about more than just fitting ductwork in place—it’s about delivering a system that performs optimally for years. At Doby Verrolec, we’ve worked closely with contractors and consultants across commercial, industrial, healthcare and high-spec public sector buildings. The best installations follow proven principles that maximise airflow, reduce waste, and ensure compliance.

1. Minimise Air Leakage from the Start

Air leakage is one of the most common causes of poor HVAC performance. Even minor gaps at joints or seams can drastically reduce system efficiency.

Doby insight: On a data centre project, high system leakage led to pressure imbalances and higher cooling costs. Switching to Doby flanged duct connectors with tested gaskets and sealants helped achieve Class C air-tightness and brought the system within spec.

Best practice:

• Use tested duct sealing systems, like Doby’s self-sealing flanges and gasketed components.
• Avoid over-tightening bolts which can damage gaskets.
• Always pressure test critical zones post-installation.

2. Maintain Correct Airflow and Balancing

Poor layout or misaligned dampers can cause inconsistent airflow between zones, increasing occupant complaints and system load.

Doby insight: In an education project, classrooms closest to the AHU were over-supplied while distant zones lacked airflow. This was traced to balancing dampers that were inaccessible or missing. Retrofitted access panels enabled commissioning teams to make adjustments and restore comfort.

Best practice:

• Plan for balancing dampers and test points early.
• Use access panels to allow future adjustments.
• Size ducts accurately to prevent velocity noise and resistance.

3. Incorporate Acoustic and Vibration Control

Ductborne noise can quickly become a tenant issue in offices and residential schemes.

Doby experience: In a mixed-use development, the mechanical contractor used acoustic linings but failed to isolate vibration at riser penetrations. The resulting structure-borne noise led to post-handover complaints. Doby’s bracket systems with anti-vibration options were later introduced to mitigate the issue.

Best practice:

• Use acoustic linings for high-speed ducts or those near occupied zones.
• Specify vibration-isolated hangers where ducts penetrate slabs or connect to fans.

4. Ensure Proper Thermal Insulation

Thermal losses can reduce system efficiency, particularly in long duct runs or where temperature control is critical.

Best practice:

• Use insulation materials with appropriate vapour barriers.
• Back to News

  Share On