Can Flex Ducts Grow Mould?

Can Flex Ducts Grow Mould?

Can Flex Ducts Grow Mould?

Within your home or space, having mould is not only unsightly with a distinct and unpleasant odour, its also a health hazard for any occupants, as well as a structural hazard if it is left to spread.

With this in mind, it’s even worse to think what could happen if mould became present in your ducting. In this blog, we will answer the question ‘Can flex ducts grow mould?’

To prevent mould, fresh air should constantly be introduced into your dwelling daily, as it helps to regulate temperature and reduce condensation. Introducing fresh air can be as simple as having a ventilation routine, or installing extractors or PIV systems. Almost all of this is facilitated by ducting.

Knowing the length of time your flexible ducting should last is key in knowing whether or not you should replace your ducting. And sometimes, whether it is insulated or not may affect that.

I-Sells is here to provide the answers you need whilst also supplying you with all the information you need to combat mould and have a well-ventilated home.

Do I need flex ducts?

Flexible ducting is ideal for those with limited space but still require ducting. It can also be used as a temporary option. Flexible ducting can come in plastic or metal, applicable in home/accommodation settings, or industrial settings. An example of flexible ducting can be seen in conjunction with vented tumble dryers.

The Pros and cons of flexible ducting


  • It is flexible by nature which by default makes it easier to install & manipulate post-installation if needs be.
  • Can be installed in tight or confined spaces.
  • Option for transparent ducting to be able to see potential blockages.
  • Can be used as a temporary ducting system


  • Due to the flexible nature of this ducting, there is a higher likelihood of punctures, subjective to placement.
  • Regular maintenance checks should be carried out to guarantee efficiency.
  • Mostly suitable for internal mounting

Are flex ducts the same as flexible ducting?

Yes, flex ducts, flexi ducting etc are just shortened terms for flexible ducting, unless there is a specification, they all serve the same purpose, although they may be made from different materials and have different lengths.

Can flex ducts grow mould?

Can flex ducts grow mould?

Unfortunately, yes, flex ducts have the ability to develop mould, though there are specific circumstances in which this can occur. It can grow on the outside with an uninsulated duct, as it is less protected by condensation and the temperature changes in that room.

If mould grows inside flex ducting, this means the ducting has been compromised and air has been able to get inside, changing the temperature and creating an opening for mould to grow in the usually hot and dry climate within the duct.

Mould can develop complications in people with medical problems, particularly respiratory. So the last place you would want mould is in an area that channels air, as mould can transmit through the air.

How to prevent mould in flexible ducts

You must make sure your ducting is sealed securely and free from any cracks or holes that compromise its efficiency. You must also make sure the area the ducts are installed is free from free-flowing water or leaks.

Here are some steps that you can take in order to prevent mould on your ductwork:

  • Before installing the ducting, make sure the area doesn’t have any leaks or is next to anything that can generate a lot of heat, such as a heating pipe.
  • Remove any mould in the room where the ducting will be placed.
  • Insulate the ducting
  • Track the humidity of the room with a hygrometer.

Flex ducting options

Flex ducting options

The flexible ducting we offer comes in a variety of sizes and styles, including varying diameters including an aluminium 100mm diameter,  and 102mm diameter . We have certain flexible ducting that is more suited to hot environments, all the way to ducting you can use for your tumble dryer.

Of course, we also offer ducting at different lengths to suit your needs which you can decide before ordering.

Can I cut flex ducts?

Yes, it is possible to cut flex ducts, in order to do this you will need a duct knife or a utility knife, and securing with a metal hose clip. You should make sure that before cutting your flexible ducting, you have fully extended it within the space it will be occupying.

It should not be coiled in any area except for the end that you intend to cut.

Why would I need to cut ducting?

Generally, people cut their ducting when the ducting is longer than the space it was bought to fit in. When it comes to flexible ducting, it is advisable to cut it if necessary. Having any tightly coiled, unextended areas can lead to a buildup of dust, reducing the effectiveness of the ducting over time, especially if it isn’t maintained.

Should I replace ducting when moving to a new building?

When moving to a new home, or new building it is important to speak to the previous owner/landlord etc to establish the status of the current ducting that is installed. You would want to ask how long they have been there & when were they last inspected.

Any ducting that hasn’t been updated or checked beyond 20 years is definitely in need of replacement. If they don’t have the answer, here are some key factors that would determine your ductwork being replaced without the intervention of an HVAC technician to check themselves.

  • A reduced input/output (this can indicate a large amount of dust inside the ducting)
  • Broken areas that allow air to escape, whether this is on the ducting pipe or the connecting joints
  • Condensation on the ductwork
  • If the ducting hasn’t been checked or worked on in years
  • Mould in areas neighbouring the ducting (could be an indication to mould being within the ductwork.)

What is the lifespan of ducting?

Does flexible ducting need to be insulated?

Ducting generally has a maximum lifespan of 20-25 years, if it is well-maintained, regularly checked and insulated. Regardless, metal ducting degrades over time, due to the expansion and contraction of metal in response to local relative temperature, which fluctuates seasonally.

Flexible ducting, if taken care of, with no dramatic or constant changes in its environment that require it to be moved should also last the lifetime of regular ducting. Though it is more susceptible to holes.

How to make ducting last longer

Making your ducting last longer is simple, but requires your attention and time. Here are some actions you can do to ensure your ducting lasts.

  • Insulate your ducting.
  • Repair any leaks before installing your ducting.
  • Keep your ducting as short & with as few changes in direction as possible.
  • If using flex ducting, ensure it is fully extended before installing, as air can get trapped in the spiral areas that are not extended, which causes dust to build up over time.

Buy new flexible ducting today

We at I-Sells endeavour to make sure our customers have all the information they need before choosing to invest in our mould solutions. Be sure to visit our blog page to gain knowledge on the wide array of factors and issues surrounding ventilation, mould, condensation, and much more.

We hope to have answered the question ‘Can flex ducts grow mould?’’

We understand you may have more questions, Do not hesitate to contact us for more information with regard to whatever you need our help with. If you’d like to send us an email, click here. For other contact options, see below:

Call us on 020 8463 9696

Visit us at our showroom:


Monday – Friday: 8:00 am to 5:30 pm

Saturday: 9:00 am to 12:00 pm

Sunday: Closed

15 St John’s Parade

Sidcup, Kent

DA14 6ES

United Kingdom

Share this post

Leave a Reply

Your email address will not be published. Required fields are marked *