Is Flex Duct Ok for Bathroom Exhaust Fan?

Is Flex Duct Ok for Bathroom Exhaust Fan?

Is Flex Duct Ok for Bathroom Exhaust Fan?

In almost every home, bathrooms see a lot of condensation. Like our kitchens, we must make sure that any condensation, dust or pollutants are taken out of the air we breathe and dwell in. Failure to do so, at least in regard to condensation, can result in the growth of mould.

In this blog, we will answer the question ‘Is flex duct OK for bathroom exhaust fan?’

To prevent mould, fresh air should always 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.

Knowing whether or not flexible ducting can be used in environments of a likelihood of condensation is important to know for those who have limited space for regular ducting in a generally humid environment like some bathrooms.

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.

Flexible ducting explained

Flexible ducting explained

Flexible ducting (also known as flex ducts, or flexi ducts) serves the same purpose as regular ducting, the function does not change, and the only change is the conduit in which the air travels. There are nominal differences between the two that may make one more effective than the other, but this is purely subject to your needs.

Regular ducting is solid, it can not be manipulated into specific spaces unless it is made specifically for that space. Flexible ductwork however is specially designed to be manipulated into spaces during installation ( and after if necessary.)

Flex ducts are easier to manipulate and therefore can be used in cabinets, a variety of layouts and other small spaces. (this is also thanks to its accordion-styled design.)

Advantages and disadvantages of flex ducts


  • 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

Why would I need flexible ducting?

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.

What is a bathroom exhaust fan?

A bathroom exhaust fan, also known as a bathroom extractor fan, is used to accommodate bathrooms of all sizes. The purpose is to facilitate the removal of condensation by extracting the hot air through its fan and ducting to the outside.

The efficiency of a bathroom extractor fan can be improved by simply opening the window during a hot bath or shower

What happens if I don’t have a bathroom exhaust fan?

By law, bathrooms in the UK must have a form of ventilation, either a window and/or extractor fan. If the room only has a toilet, a window is fine. Though for new-build bathrooms, an extractor fan is a requirement.

In conjunction with this, bathroom exhaust fans must fulfil the ventilation requirements of 15 litres per second/54m3 per house (this is the measurement of how much old air is replaced by new air and will be stated in the product description of the fan).

Is flex duct OK for bathroom exhaust fan?

Is flex duct OK for bathroom exhaust fan?

Yes, Flex ducts are a perfectly valid option to use a conduit for your bathroom exhaust fan. The manipulatable nature of flexible ducts allows them to fit into environments in which the connection to the outside is not a straight line.

As bathrooms are a natural environment for condensation to occur, there is a chance of mould occurring in the ducting if there is no care taken. However, this care can be as simple as using the extractor every time you shower or use the hot water in the bathroom for extended periods.

Can I use a round duct for a bathroom exhaust fan?

Yes, round ducts are also completely fine to use for a bathroom extractor fan and would be the preferred option for some.

Where to purchase flex ducts

I-Sells is proud to be the UK’s Leading supplier in ducting and ventilation, so when it comes to buying a variety of quality ducting and ventilation, we are the first port of call for HVAC experts and everyday customers alike.

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 use any kind of ducting?

Not necessarily, some ducting is more suited to home environments whilst others are more suited to industrial environments. In some instances, flexible ducting would be more optimal than round ducting, and within that, a plastic option may be better than metal.

Luckily we have two separate categories for this on our website to make it easier for you to navigate depending on your needs. Simply hover over the tab that says ‘flexible hoses’ and choose between ‘commercial’ and ‘industrial’ to begin browsing.

What is the lifespan of ducting?

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.

When should I replace flex ducting?

When should I replace flex ducting?

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 themselves
  • Condensation on the ductwork
  • If the ducting hasn’t been checked or worked on in a number of years
  • Mould in areas neighbouring the ducting (could be an indication to mould being within the ductwork.)

Purchase flex ducts 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 ‘Is flex duct OK for bathroom exhaust fan?’

We understand you may have more questions, Do not hesitate to contact us for more information with regard to whatever you may 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:


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Saturday: 9:00 am to 12:00 pm

Sunday: Closed

15 St John’s Parade

Sidcup, Kent

DA14 6ES

United Kingdom

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