Best duct for a bathroom exhaust fan

Top 4 Best Ducts For Bathroom Exhaust Fans

There’s a myriad of advantages that come with having an exhaust fan installed in your bathroom. These convenient appliances effortlessly deal with excess moisture, which can cause the accumulation of dangerous mold and also wreak havoc on the walls of your bathroom. 

They also eliminate the “foggy mirror” syndrome, reduce various airborne contaminants, as well as keep unpleasant odors at bay. 

However, a bathroom exhaust fan is worthless on its own – you also need a quality duct for it. This is an integral part of the whole exhaust system and one that actually leads humid air from the bathroom to the outside. 

If you’re looking to buy a duct for your brand new bathroom exhaust fan but don’t know much about these practical ventilation conduits, you’re in the right place. I’ll be taking a quick look at the market’s most popular models and also talk about some important considerations concerning this topic. 


Overview of the Best Ducts For Bathroom Exhaust Fans

ModelDundas Jafine Flexible DuctHon & Guan Air DuctHVAC Premium Round DuctAC Infinity Flexible Duct
Image[amazon fields="B0049H9970" value="thumb" image_size="small" image_alt="" image_align="center"][amazon fields="B07QH9LH73" value="thumb" image_size="small" image_alt="" image_align="center"][amazon fields="B082J5Y6YY" value="thumb" image_size="small" image_alt=""][amazon fields="B0791V19H7" value="thumb" image_size="small" image_alt=""]
MaterialPolyester laminate, zinc, fiberglassPVC30-gauge galvanized metalAluminum
Length25 feet16 feet25 feet25 feet
Price[amazon fields = "B0049H9970" value = "price"][amazon fields = "B07QH9LH73" value = "price"][amazon fields = "B082J5Y6YY" value = "price"][amazon fields = "B0791V19H7" value = "price"]
[amazon fields="B0049H9970" value="button" button_text="Amazon"][amazon fields="B07QH9LH73" value="button" button_text="Amazon"][amazon fields="B082J5Y6YY" value="button" button_text="Amazon"][amazon fields="B0791V19H7" value="button" button_text="Amazon"]

The Best Duct for Bathroom Exhaust Fans 

Dundas Jafine Flexible Duct

Dundas Jafine duct


  • Highly flexible 
  • R6 insulation value 
  • Effortless installation 
  • 25-feet long & 4” diameter 
  • A fire & UV-resistant construction 

Almost flawless, this phenomenal duct from Dundas Jaffine provides an excellent value for the money. 

It features a multi-layered construction with a number of different materials that make it high-performing, UV-resistant, fire-resistant, and highly flexible. 

In addition, the model reduces condensation and heat loss and is incredibly easy to install. To put it simply, it is the best product of this type you can get on today’s market. 

[amazon fields=”B0049H9970″ value=”button” button_text=”Check Price on Amazon”]

Reviews of the Best Ducts For Bathroom Exhaust Fans

1. AC Infinity Flexible Duct

AC Infinity duct


  • Length: 25 feet 
  • Diameter: 6”
  • Material: Aluminum 

[amazon fields=”B0791V19H7″ value=”button” button_text=”Check Price on Amazon”]

The very first bathroom exhaust fan duct I’ll be taking a look at is the 6-inch aluminum model made by a company called AC Infinity. It’s a high-quality, aluminum-made duct designed for general HVAC usage. 

As mentioned above, the main material used in the manufacture of this product is aluminum. However, the AC Infinity Flexible Duct also sports an outer PVC layer. This particular part helps prevent air leaks and is highly resistant to cuts. 

Another great thing about this duct is that it’s very easy to install thanks to its steel-wire spiral structure. In addition to that, it arrives together with two convenient metal duct clamps. 

With a diameter of 6”, this model is a particularly good choice if you have a bathroom exhaust fan that requires a larger duct.


  • 25-feet long
  • Large diameter 
  • Comes with duct clamps 
  • Resistant to cuts, tears, and leaks 


  • Not insulated 

2. HVAC Premium Round Duct

HVAC premium duct


  • Length: 25 feet 
  • Diameter: 5”
  • Material: 30-gauge galvanized metal

[amazon fields=”B082J5Y6YY” value=”button” button_text=”Check Price on Amazon”]

Next up is a metal sheet duct made by HVAC Premium. Besides the 25-feet long variant we’re looking at here, this duct is also available in a 10-feet variant. 

Obviously, the best thing about this particular model is how exceptionally durable it is. Moreover, it is smooth-walled, i.e. it has no ridges and thus provides excellent airflow. 

The 30-gauge galvanized metal used in the manufacture of this duct is very resistant to oxidation and corrosion. As such, it should serve you well for a long time – you won’t have to worry about having to replace it anytime soon. 

In terms of dimensions, HVAC Premium Round Duct has a 5” diameter and it’s 25 feet long, as stated above. It arrives in ten separate sections that you have to connect together.

If you are looking for a fan as well, check out our pick for the best round bathroom exhaust fan.


  • 25-feet long 
  • Extremely durable 
  • Provides excellent airflow 
  • Resistant to oxidation & rust 


  • Changing its directions requires the use of elbows 

3. Hon & Guan Air Duct

Hon and guan duct


  • Length: 16 feet 
  • Diameter: 3” 
  • Material: PVC

[amazon fields=”B07QH9LH73″ value=”button” button_text=”Check Price on Amazon”]

Do you have an older bathroom exhaust fan? If so, this Hon & Guan duct is an ideal option for you – its diameter stands at only 3 inches. 

However, this doesn’t mean that the Hon & Guan Air Duct performs poorly. In fact, it was designed in such a way that it significantly reduces noise created by carbon filter systems and bathroom exhaust fans. 

Furthermore, the model sports a multi-layered construction – two layers of aluminum foil and one PVC layer. It is resistant to rips while also being very flexible and easy to install. 

If you have a larger fan, on the other hand, keep in mind that the model is also available in 4”, 5”, and 6” variants.

See our pick for the best bathroom window exhaust fan as well.


  • Ideal for older bathroom exhaust fans 
  • Significantly reduces noise 
  • 3-layer construction 
  • Affordable 


  • No clamps included

4. Dundas Jafine Flexible Duct

Dundas Jafine duct


  • Length: 25 feet
  • Diameter: 4”
  • Material: Polyester laminate, zinc, fiberglass

[amazon fields=”B0049H9970″ value=”button” button_text=”Check Price on Amazon”]

The Dundas Jafine Flexible Duct is, in my opinion, the best bathroom exhaust fan duct you can get on today’s market, and for a couple of good reasons. 

First of all, it is 25 feet long and has a diameter of 4 inches, which makes it suitable for use with most bathroom exhaust fans out there. Secondly, the model is very flexible – it can be installed in tight spots without the need to use elbows. 

The combination of a fiberglass insulating blanket, rust-resistant zinc wire and the double-walled polyester laminate all work together towards providing the best possible performance. The duct is also fire retardant due to its vapor barrier. 

All in all, this highly-insulated duct provides a phenomenal value for the money and effortlessly wins the status of my #1 pick.

If you would like to get a fan with a light, check out our post on the best bathroom exhaust fans with a light.


  • 25-feet long 
  • Rust & UV-resistant 
  • Fire retardant vapor barrier 
  • Flexible & easy to install 


  • May increase bathroom exhaust fan noise 

What’s a Bathroom Exhaust Fan Duct? 

The duct is a type of tube that allows the bathroom fan to exhaust excess moisture to the exterior. 

This ventilation conduit can vent the humid air into the attic, or to the outside through a wall. Check out our post on venting a bathroom exhaust fan into the attic for more information.

Wherever it vents the excess moisture, the duct is a vital part of your bathroom’s exhaust system. Your fan won’t be able to move the humid air to the outside in case the duct is not working properly. 

Foil Ducts

Foil bathroom duct

A vast majority of ducts for bathroom exhaust fans are made out of aluminum foil – it’s the most commonly used material. 

These kinds of ducts are very flexible. As you can already guess, their flexibility turns them into a great choice for homeowners who have a couple of bends in-between the exterior and the bathroom exhaust fan. Unfortunately, however, this same flexibility also makes foil ducts susceptible to tears. 

A lot of manufacturers of foil ducts tend to coat them with materials such as PVC. The result of this is increased durability and strength. In addition to these kinds of ducts, you may also want to consider using a duct made out of sheet metal (more on that later). 

The relative ease of installation – as well as affordability – are undoubtedly the biggest benefits of opting for flex ducting. As they require no elbows, these kinds of ducts are quite easy to set up. Routing a flexible foil duct around corners and walls is a job that can be done by pretty much anyone. 

Sheet Metal Ducts 

The main reason why a lot of homeowners often want to use metal instead of foil ducts is quite obvious – they are significantly stronger. 

There are, however, several other reasons, with one of the most important ones being the fact that there are no inner ridges inside sheet metal ducts. This allows them to deliver better airflow, among other things. 

Obviously, better airflow can only enhance the performance of your bathroom exhaust fan and allow it to remove smells and moisture more efficiently. 

There are also some disadvantages to opting for a metal-made duct. When compared to foil ducts, sheet metal ducts are considerably more difficult to install. This is particularly true for models that have a lot of bends. 

You’ll have no other choice but to install a sheet metal elbow for each of these bends. It goes without saying, but this process can be quite time-consuming. 

The Sizes of Ducts for Bathroom Exhaust Fans

Duct on an exterior bathroom fan

Almost all older bathroom exhaust fans use ducting whose diameter stands at 3 inches. If the exhaust fan inside your bathroom was set up 15 or more years ago, it is almost certainly connected to a smaller-width duct. 

Modern bathroom exhaust fans, on the other hand, use 4”, 5”, or 6” ducting. 

While it’s possible to use a small-width duct with a modern bathroom fan, doing something like that is bound to decrease the unit’s performance. What is more, it will almost certainly void the warranty. 

A fan that uses larger width ducting is capable of removing more air while using less energy – it’s as simple as that. Another important thing to point out here is that using a larger bathroom exhaust fan duct can greatly reduce the noise produced by this appliance. 

So, if you want your bath fan to be as quiet as possible, make sure to use 4”-6” ducting. 

Scroll to Top
Scroll to Top