How Long Does Metal Ductwork Last?

How Long Does Metal Ductwork Last?

How Long Does Metal Ductwork Last?

To prevent mould, fresh air should constantly be introduced into your dwelling daily, as it helps to regulate temperature and reduce condensation. But what about the ductwork itself? How long does metal ductwork last?

In this blog, we will provide an answer as well as key guidance in understanding ductwork. It is vital to be aware of your ducting system.

Old and/or rusty ductwork can compromise your whole ducting system, and if left unchecked, will end up with you paying more in repair work in addition to new ducting.

Knowing how long metal ducting can last, can save you time and money in the long-term, inefficient ducting that is past its life cycle can pose a health hazard especially if mould has invaded your ducting system.

If left unattended, mould can create serious health issues, and if ductwork grows mould, it can defeat the purpose of ventilation as well as jeopardise the health of the occupants of the building.

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.

What is round and flat ducting?

Metal ductwork can come in flat channel, and round ducting. Below is a brief explanation.

Round ducting:

Round ducting has the highest airflow performance, this is due to a wider diameter increasing its free area. The lack of corners also decreases resistance within the pipe, which allows for higher airflow rates and higher rates of ventilation.

It is recommended for most applications where space is available for installation. Its main purposes are for long ducting runs, whole-house ventilation systems, HVAC systems, bathroom, toilet and utility room extract fan venting, or any occasion where high rates of extraction are required.

Flat channel duct

Square ducting (also known as flat channel ducting) is ideal when a low profile is required due to a lack of space. It can also be concealed and flush fit against ceilings and walls or within voids.

As a result of a lower free area, there is greater pressure created within a duct run. It is therefore essential that you check the manufacturer information for the fan you are planning to install within the run. 

Pros & Cons of Round Ducting



High Airflow

Difficult to conceal

Less friction

Poor results in low-pressure systems


More expensive than flat ducting



Better for high-pressure systems


Designed for HVAC systems


Pros & Cons of Square (Flat Channel) Ducting





Creates more noise within duct run



Poor results within high-pressure systems

Easy to flush fit and conceal

Increased air resistance

Ideal for low-pressure




The basics of metal ductwork

Metal ducting is ideal for ventilation systems that are set up in hotter environments. Metal ducting is also a popular choice for spaces and environments with air rich in certain compounds that could be hazardous.

HVAC experts and engineers typically choose to rely on stainless steel for aggressive environments, where corrosion is highly likely, usually in industrial settings.

The benefits of metal ducting are as follows:

  • It can be used in rooms that have appliances that emit a lot of heat
  • High-quality galvanised aluminium ensures long-lasting function
  • Ideal for industrial environments
  • Can be insulated.

Buying metal ducting

Alongside being a provider of mould solutions like extractor fans and PIV systems, I-Sells also provide ducting for those looking to buy and install their ducting themselves.

We provide round ductwork fittings and accessories in a large range of diameters to suit all purposes including HVAC systems and extractor fans. Our metal ductwork is manufactured from high-quality galvanised Aluminium

How long does metal ductwork last?

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.

When moving into a new home or building, you should enquire about the age of the current ducting system to know if it needs replacing or upgrading to a modern HVAC system.

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.

When should you replace metal ducting?

One of the key factors in preventing or delaying the onset of rust on your metal ductwork is ensuring there is no condensation appearing on the ducting.

You can stop condensation on metal ductwork most of the time, however, the only exception to this would be instances of dramatic temperature fluctuations that occur due to freak weather occurrences, a lack of electricity to power the ventilation system or a combination of both.

These occasions are extremely rare. But here are some things you can keep track of, to ensure your ducting does not develop condensation.

  • Check your ducting for any leakage, is there holes? Are they sealed?
  • Apply ducting insulation
  • Use ducting tape on secure connections to further ensure their efficiency
  • Check your ducting for rust, and/or condensation on the outside of the ductwork

Generally, the likelihood of metal ductwork growing mould is very low. However, this can happen if certain circumstances are met. A clean, sealed duct will present an environment where mould can’t grow, this changes with the introduction of dust & humidity.

Why else would my ducting need replacing?

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.)

Is ducting better than AC?

This is a personal preference and is relevant to the space each system operates in, the main difference between the two is the redistribution of air.

Ventilation systems that utilize ducting make use of fresh outdoor air which replaces the extracted indoor air, whereas Air Conditioning systems condition and redirect the air of the room it is in.

Air conditioning in addition to an open window can help redistribute fresh air with a similar effectiveness to ducting whilst using less space than HVAC solutions that incorporate ducting. However, ducting systems by their nature facilitate the introduction of fresh air and extraction of allergens etc.

Buy metal ducting today

We at I-Sells endeavour to ensure our customers have all the information they need before investing 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 ‘How long does metal ductwork last?’

We understand you may have more questions, please 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:


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

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