Flexible ducting plays a critical role in how well kitchen and bathroom ventilation actually works. Even with a powerful extractor fan in place, poor ducting choices can severely restrict airflow, increase noise, and cause long-term issues such as condensation and mould.

Many of the most common ventilation problems are not caused by the fan itself, but by avoiding a few ducting mistakes made during selection or installation. This guide highlights the most common errors homeowners and installers make with flexible ducting—and explains how to avoid them for better airflow and long-term performance.

Mistake 1: No Airflow Control at the End of the Duct

One of the most overlooked parts of a ventilation system is how air exits the duct. Without proper airflow control, extracted air can escape inefficiently or even re-enter the room.

This often happens when flexible ducting is connected directly to an external opening without an air valve, diffuser, or damper to guide and regulate airflow.

In kitchens and bathrooms, this can lead to:

• Uneven airflow
• Noise caused by uncontrolled air movement
• Backflow during windy conditions

Better solution:

Use Diffusers & Dampers or an appropriate air valve at the termination point. These components help regulate airflow and improve overall system efficiency.

Mistake 2: Using the Wrong Type of Flexible Ducting for the Application

Not all flexible ducting performs the same way. A common mistake is choosing the cheapest or most readily available ducting without considering airflow resistance or durability.

For example, lightweight ducting may collapse or restrict airflow in longer kitchen duct runs, especially behind cabinets or in ceiling voids.

Better solution:

• Use Semi Rigid Flexible Ducting where better airflow and structural support are needed
• Choose Combination Flexible Ducting when balancing flexibility with improved internal airflow is a necessity

These options reduce sagging and turbulence compared to standard flexible ducting.

Mistake 3: Ignoring Condensation Control in Bathroom Ducting

Bathrooms create warm, moisture-heavy air. When this air travels through uninsulated ducting in cold spaces, condensation forms, reducing airflow over time.

This is a frequent issue in loft-mounted bathroom extractor ducting.

Better solution:

Apply Duct Wrap or use insulated ducting solutions to keep the air warm until it exits the building. Proper insulation reduces the buildup of internal moistureand helps maintain efficient airflow.

Mistake 4: Poorly Secured Ducting Runs

Flexible ducting that isn’t properly secured tends to sag, kink, or pull away from connections. This creates airflow resistance and increases noise, particularly in longer kitchen duct runs.

Loose ducting is also more likely to leak air into ceiling voids or cupboards.

Better solution:

Use Ducting Clips to support and secure duct runs at regular intervals. This keeps the ducting aligned, extended, and free from unnecessary bends.

Mistake 5: Cold Air Coming Back In - No Backdraft Protection

Another common problem is cold air entering the property through ducting when the extractor fan is switched off. This is especially noticeable in bathrooms and utility rooms during colder months.

Without protection, ducting can act like an open channel between indoors and outdoors.

Better solution:

Install a Draught Shutter to prevent backflow when the fan is not in use. Draught shutters improve comfort and stop cold air, smells, and insects from travelling back through the duct.

Mistake 6: Mixing PVC Ducting Incorrectly with Flexible Ducting

PVC ducting is often used for straight sections, while flexible ducting handles bends and tight spaces. Problems arise when these are poorly joined or lack proper accessories.

This can cause air leaks, misalignment, and vibration noise.

Better solution:

Use PVC Ducting for straight runs and transition smoothly to flexible ducting using compatible ventilation accessories to maintain airtight connections.

Mistake 7: Treating Accessories as Optional Extras

Many airflow issues aren’t caused by the ducting itself, but by missing accessories. Items such as clips, dampers, duct wrap, and draught shutters are often skipped to save cost, but this usually results in poorer performance.

Better approach:

Think of ventilation as a system. Flexible ducting performs best when supported by the right ventilation accessories, selected for the room’s requirements and the ducting’s installation type.

FAQs

1. Do I really need dampers or air valves?

Yes. They help control airflow, reduce noise, and improve extraction efficiency.

2. Is duct wrap necessary for bathroom ventilation?

We highly recommended for loft runs to prevent condensation inside the duct.

3. Are ducting clips important?

Yes. Proper support prevents sagging and airflow restriction.

4. What stops cold air from coming back through the ducting?

A draught shutter prevents backdraft when the fan is off.

Final Thoughts

Hopefully, this flexible ducting guide provided insight into mistakes that are often overlooked but have a significant impact on ventilation performance. Avoiding these common mistakes ensures smoother airflow, reduced condensation, and quieter operation in both kitchens and bathrooms.

By learning to choose the right ducting, installing it correctly, and matching it to the room environment, you will give your ventilation system the best chance to work effectively. 

Explore our range of flexible ducting solutions designed for better airflow in kitchens and bathrooms.