Top 4 Best Ducts For Bathroom Exhaust Fans (2020 Review)

Do you want to learn how to prevent mold in a bathroom even if you don't have an exhaust fan?

Mold can grow on almost any surface, but bathrooms are especially susceptible to mold because of the wet and damp conditions.

In this guide, I will go over...

  • Opening a bathroom window or using a dehumidifer
  • Regularly clean your grout and caulking
  • Paint the walls with a higher gloss paint

Let's get started with this guide!

top best rated duct for bathroom exhaust fan review

My Overall #1 Rated Pick

top best rated duct for bathroom exhaust fan review dundas jafine
  • 4" Flexible Duct (25' Long)
  • Includes R6 Insulated Jacket
  • Tear Resistant Vapor Barrier
  • Class 1 Fire Rating

My overall top pick for the best duct for bathroom exhaust fans is made by Dundas Jafine. This is a 4-inch wide duct that is 25 feet long when fully stretched out. The great thing about this budget friendly duct is that it is insulated. The insulation is rated at R6 so it will help prevent condensation problems and water (or mold) damage. It also includes a tear resistant vapor barrier and a Class 1 fire rating.

ImageProduct
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Dundas Jafine
  • R6 Insulation
  • 25' Long
  • Vapor Barrier
  • R6 Insulation
  • 25' Long
  • Vapor Barrier
View on Amazon
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Hon&Guan
  • 3" For Old Fans
  • 3 Layers
  • Low Noise
  • 3" For Old Fans
  • 3 Layers
  • Low Noise
View on Amazon
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Sheet Metal Duct
  • 30-Gauge Metal
  • Smooth Walled
  • 20' Long (10 Sections)
  • 30-Gauge Metal
  • Smooth Walled
  • 20' Long (10 Sections)
View on Amazon
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AC Infinity
  • Includes Clamps
  • Tough Outer Layer
  • 25' Long
  • Includes Clamps
  • Tough Outer Layer
  • 25' Long
View on Amazon

Top 5 Best Ducts For Bathroom Fans

My top picks for the best ducts for bathroom fans range from 3-inch to 6-inch. Most of these ducts are highly flexible but one is rigid sheet metal. The flexible ducts are easier to install but tend to have less air flow and can rip easily. Check them out below...

  1. Dundas Jafine (Insulated 4-inch) (Top Pick)

  2. Hon&Guan (3-inch)

  3. Sheet Metal Duct (4 inch) (Best Air Flow)

  4. AC Infinity (6-inch)

What Is A Duct For Bathroom Exhaust Fans?

The duct is the vent that goes from the bathroom exhaust fan to the exterior.

This vent duct can go to the exterior through a wall, or it may go through an attic. 

Either way, the duct is an important part of the exhaust system and must be working properly to remove moisture to the outside.

Read Also: How To Prevent Mold in Bathrooms Without Fans?

Foil Ducts

The most common material that a bathroom duct is made of is aluminum foil.

These flexible foil vents are great if you have a few bends in-between the exhaust fan and the exterior. Unfortunately, these flexible ducts are also prone to tears.

Some manufacturers coat these foil ducts with PVC or other material in order to give it more strength and durability. In addition to the flexible foil type of ducts, homeowners should also consider using sheet metal ducting.

Probably the biggest advantages of flex ducting are the low cost and ease of installation. You can install a flex vent so easily because elbows aren't required, you can just route the flex duct around walls and corners without an issue.

Read Also: What Are The Best Panasonic Bathroom Exhaust Fans?

top best rated duct for bathroom exhaust fan reviews

Sheet Metal Duct

The obvious reason to use sheet metal ducts is because they are significantly stronger than flexible ducts.

But the less apparent reason to use sheet metal is that there are no inner ridges, so it delivers better air flow. And with stronger air flow, the bathroom fan just works better at removing moisture and smells.

The downside is that sheet metal ducts can be much more difficult to install, especially if there are numerous bends. For each bend, you will have to install a sheet metal elbow, and this process can add much more time to the installation.

Read Also: Why Did The Bathroom Fan Stop Working?

Duct Sizes

The most common size for older bathroom fans is 3-inch width ducting. When I inspect older homes (15-years or older), the bathroom fans almost always use this smaller width ducting. However, almost all new bathroom exhaust fans use either the 4-inch or 6-inch duct.

You probably can still use a 3-inch duct with new bathroom fans, but the performance may be significantly reduced, and it also may void any warranty.

When you have a larger width duct, the bathroom fan can exhaust more air and with less energy. Also, with larger ducts, it can significantly reduce the noise of bathroom exhaust fans—one of the most common complaints of homeowners. 

Read Also: What Are The Best Broan-Nutone Bathroom Fans?

What Is The Best Duct For Bathroom Exhaust Fans?

Here are my full reviews of the best ducts for bath fans together with their pros and cons. Check it out below...

Dundas Jafine makes a high quality 4-inch insulated duct that can be used for bathroom fans (or any other HVAC application).

It includes a Class 1 fire rating to help prevent the spread of fires. The Dundas Jafine is also strong yet highly flexible so you never need elbows and it can be installed in tight spots.

The exterior insulated jacket is made of fiberglass insulation with a R-value of 6.

There is a polyethylene outer covering over the insulation that makes it even more durable, and also acts as a vapor barrier. The polyethlyene is also UV resistant.

  • R6 insulated jacket
  • 25-feet long (4" wide)
  • Tear resistant vapor barrier
  • Budget friendly
  • Difficult to attach to rigid duct
  • May increase fan noise

The Hon&Guan is a quality 3-inch flexible duct fan that can be installed for bathroom fans. This duct hose has been designed to reduce noise by up to 50% as compared to standard flex ducts.

The 3-inch width is a standard size for many older bathroom fans unlike newer fans which use 4 or 5 inch vent ducts.

It features a tough 3-layer duct materials: the outer layer is made out of PVC and then two layers of aluminum foil. This flexible bathroom fan duct is 16-feet long but it can also be easily cut to fit your duct run.

  • 3-inch duct (great for older fans)
  • 3 layers of material (PVC & 2 layers of foil)
  • Designed to reduce noise by 50%
  • Not insulated
  • Does not come with clamps

This product made by HVAC premium is a 20-foot sheet metal duct that can be used for bathroom exhaust fans. It comes in ten 2' sections that you connect together at the crimped ends.

Even though the ends are crimped, I recommend that you seal each connection with aluminum foil tape. The duct is made out of 30-gauge galvanized sheet metal, and it will resist rust and corrosion.

The nice thing about sheet metal ducts for a bathroom fan is that it will have better air flow than flexible vents because there aren't 'ridges' and it is smooth.

  • Smooth walled for better air flow
  • 30-gauge sheet metal for strength
  • 20 foot long (ten 2' sections)
  • Not insulated
  • Not flexible (requires elbows if you change direction)

This is a high quality 6-inch (25' long) duct made by AC infinity designed the HVAC and can be used for newer bathroom fans that require large ducts.

It features an inner aluminum foil layer, and an outer PVC layer. The outer PVC thermoplastic layer gives it strength, resists cuts, and helps prevent air leaks.

The inner aluminum foil is heavy duty and is fire resistant. And it is flexible so you can install this in multi-angled duct runs. This AC Infinity duct also comes with two metal duct clamps.

  • Comes with duct clamps
  • Tough outer PVC layer
  • Flexible inner foil layer
  • 25-feet (stretched out)
  • Not insulated

My #1 Top Pick: Dundas Jafine (Insulated 4-inch)

My overall top pick for the best duct for bathroom exhaust fans goes to the Dundas Jafine. Here's why...

#1. Insulation

One common issues with bathroom ducts is that condensation (water) can form on the outside due to temperature differences. And then this water can fall onto sheetrock or wood and cause damage (or mold). The insulated sleeve is R6 and has a Class 1 fire rating.

Read Also: How Do I Stop Condensation In My Bathroom Fan?

#2. Flexible

This 25-foot long duct has a flexible aluminum foil hose that can be routed around bends and corners without a problem. Of course, you still want to keep bends to an absolute minimum to keep air flow maximized.

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Arie Van Tuijl

Arie Van Tuijl

Arie is the founder of Home Inspector Secrets, an online resource dedicated to helping people understand how homes work. He is a licensed home inspector in two U.S states and owns a residential and commercial inspection company (read his full bio on the About page). To ask Arie a question, please use the comment box at the bottom of the relevant article.

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