Plastic Ducting – Types, Benefits and Application

Plastic ducting

What is Plastic Ducting

If you have browsed a bit through our categories by now, you most likely realised how many options you have for ducting pipes. Different sizes, shapes and materials are used in making ducting pipes, and each one of them has its features and downsides. According to the application you are building a system for, you should choose the right duct pipes for your project, to make it efficient and durable.

One of these types is plastic ducting. Obviously, it is made out of plastic, more specifically PVC. They’re a suitable solution for controlling condensation or mould appearance in interior spaces. When installing an extractor fan or passive ventilation system, plastic ventilation ducting may be of significant help.

Types and Sizes

Plastic ducting is available in two different types. Each one of them is suitable for different scenarios.

Plastic pipe types:

  • Rectangular ducting;
  • Round plastic ducting.

The difference between the two plastic duct types is their shape and flee area or the available space in the duct. It is what gives one an advantage over the other in the planning process, but we are going to talk about that a bit later. Now let’s get familiar with the most common sizes of those ducting pipes.

Round plastic ducting sizes:

  • 100mm;
  • 125mm;
  • 150mm.

*the most common size is 100mm plastic ducting

Round plastic ducting has specific properties that make it preferable. For instance, it has the greatest airflow performance. On the downside, it can be challenging to hide and install as opposed to plastic ducting for ventilation, where the airflow rate is not as great but it can easily be hidden in voids and flush fit. The airflow and ventilation are better when there is more space available in the plastic duct pipe.

This type of ducting doesn’t have any corners, which means a lower resistance in the pipe. Round plastic ducting is ideal for interiors where there is enough space for installation. It’s mostly used for:

  • Long ducting runs
  • Whole-house ventilation systems
  • HVAC systems
  • Bathrooms
  • Toilets
  • Utility room extractor fan venting

It can also be selected for venting exhaust odours and cooker hood steam but some people will prefer to use flexible plastic ducting as the installation process is simpler in a lot of cases.

Rectangular plastic ducting sizes:

  • 110 x 54mm;
  • 204 x 60mm;
  • 220 x 90mm.

Rectangular plastic ducting is also called flat plastic ducting or square plastic ducting. This type of solution is a common choice in spaces that are limited in size. It can easily be hidden in voids or against walls and ceilings. The pressure produced in a duct run is higher due to the lower free area. In other words, it’s important to read the provided instructions for the fan before the installation to prevent overheating or burning out. Some of the most common applications of flat channel plastic ducting include:

  • Bathrooms
  • Toilets
  • Utility rooms

Benefits of using Plastic Ducting

The benefits of using this product over others are a few. First of all, and probably most important, excellent airflow characteristics with minimum air turbulence. The effect comes from the smooth internal bore of the pipes. This goes mostly for the round plastic ducting pipes, thanks to their shape. However, both types are lightweight making them easy to install with less mounting points and connections, compared to other products.

Some types of plastic ducting are also cheaper. When you add that to the less amount of mounting accessories you really can save some money while using PVC ducting. This material is easy to work with, it can easily be cut to size with the use of a saw blade or similar tool. If the plans for the system are correct, the installation is a breeze.

Those ducting pipes are also solid, with thick walls and are rigid enough to withstand light blows and rattles. The losses in pressure, the amount of air that escapes from various holes and connection points of the system, are insignificant. Almost close to none.

Above all that, if you ever need to switch from one type (round plastic ducting) to the other (rectangular ducting) you can easily do so via a special fitting piece called transformer. But why would you need to switch from one to the other in the first place? Well, let’s answer this question in the following paragraph.


This product is probably the perfect solutions for ventilation systems. Most times those systems must be concealed, hidden somewhere in walls, ceilings or even floors. Temperature differences, leaking pipes and bad isolation can easily be reasons for those crevices in the building to have higher levels of humidity. A benefit of PVC ducting pipes is that they are highly corrosion resistant. The moisture in the air which travels through the ducting pipes of a ventilation system is another factor that brings corrosion risk levels way up. If you decide to use steel ducting pipes they will not last long in such conditions.

But if they are all that great, why do we have two options on the market? Why won’t just use round plastic ducting all around? Although round pipes should always be the go-to option, especially for long-range systems, rectangular ducting has one benefit that no other product has. They are more easy to fit in tight spaces. Given the above-mentioned fact that ventilation systems are often hidden in the structure, tight spaces and corners are common. With rectangular ducting, we can fit the system in tighter spots and we can easily run it between pillars and other obstacles. This is why rectangular ducting is used over round ones, even if within one full system. Here is where the “transformer” fittings come in handy.

For your convenience, you can always call our trained experts at 01455 616444 to help you with choosing the right plastic ducting, or any other ducting supply you might need.