Can You Put Insulation Around Bathroom Exhaust Fan?

Your bathroom exhaust fan does a very important job: it takes the air in the room and takes it elsewhere. It’s beneficial if you want to cut back on how steamy the bathroom gets during a shower or, say, get rid of a particularly unappealing smell.

However, is such a fan supposed to be insulated? Can you and should you put insulation around the bathroom exhaust fan or in the duct itself? We’ll be answering all of those questions here.

Is the Exhaust Fan Supposed to be Insulated?

The short answer is yes. Bathroom exhaust fans are supposed to be insulated, but they are supposed to be insulated very well. There’s a variety of reasons for this, all of which we’ll discuss.

However, please note that you don’t put insulation around the actual fan or its fastenings in your bathroom. You insulate the air duct connected to the fan, which you will almost always find in your attic.

Improving the Air Quality

There are a lot of things that affect the quality of the air in our bathrooms. Sometimes it’s just steam, other times it’s a stench, and a lot of times it’s the harsh chemicals that are often used to clean bathrooms when it comes time to do that.

A well-insulated exhaust fan does a much better job of efficiently venting out all of those things, meaning less of those things in your air, which is good for your comfort and health. Generally speaking, a well-insulated exhaust fan does a better job of circulating fresh air into the room.

This means the air in the bathroom is less stagnant, so pollutants don’t hang around as long, and the environment is less conducive for things like mold or other spores. A constant flow of fresh air also helps prevent foul odors from sticking around.

Preventing Excess Moisture

When an exhaust fan isn’t insulated as well as it is supposed to be, it doesn’t circulate the moisture out of your bathroom as well as it is supposed to. And when it isn’t getting rid of as much moisture as it is supposed to, you start getting excess moisture in your bathroom.

Lingering moisture in the air and on bathroom surfaces causes various bad things: doors can warp, wallpaper and paint can peel, water stains can form, and mold or mildew is more likely to take root. 

Mold is dangerous because it’s difficult to get rid of, and prolonged exposure can cause serious health problems. Water stains are also a problem because if a lack of exhaust fan insulation causes them, they are usually near the exhaust fan itself. Now, onto the reasons why insulation is good.

Temperature Regulation

A well-insulated exhaust fan also serves a purpose as far as temperature regulation is concerned. When the fan is properly insulated, it can maintain a relatively even and comfortable temperature instead of being far too hot or too cold. Of course, this does have to do with humidity as well.

Installing Insulation for Your Exhaust Fan

OK, so there is plenty of reason to insulate your exhaust fan, as we’ve already discussed. But how do you go about doing it? Well, you could always hire a contractor to do it for you, which is fine if you don’t want to do it yourself, but that costs money.

On the other hand, you could insulate your exhaust fan with your own hands. It’s not a particularly difficult thing to do, so if you’re willing to get it done yourself, you may as well save some money.

Fixing Loose Insulation

First of all, your exhaust fan duct probably already has insulation. Most of them are supposed to be insulated when they are installed, at any rate. But if your bathroom fan doesn’t seem to circulate the air too well or get rid of moisture that effectively, the insulation itself may be loose.

Thankfully, fixing this type of problem isn’t too hard. Usually, you can tighten or fasten the insulation using tools as simple as aluminum tape or zip ties. 

Ducts With Interior Insulation

Some ducts have interior insulation, as in, insulation within the duct itself. Believe it or not, this is a bad thing. This type of insulation tends to catch moisture between itself and the actual duct, which creates an ideal environment for germs to thrive, not to mention the potential for strong odors.

You could attempt to remove such insulation yourself, but you’d probably be better off just buying a new duct that doesn’t have much insulation. After all, they aren’t expensive, and installing a new duct isn’t that difficult either.

Choosing Insulation for Your Fan Duct

If you need to add completely new insulation to your exhaust fan, there’s only one thing to consider when choosing that insulation, and that’s the R-value. R-value is a measurement of how resistant the material is to heat flow. The higher the number, the more resistant.

There’s a great range when it comes to these R-values, but when looking for insulation material, you should focus on R-3 to R-6. Most insulation material within that range will serve just fine.

Wrapping Insulation Around the Outside of the Duct

As said before, you want your insulation to be outside the duct, not inside. You’ll be wrapping it around the outside, which is an easy enough thing to do. The simplest method is to take a sharp knife and cut the insulation material into strips that will snugly fit each side of your duct.

You need to ensure that all the seams are properly closed and that the insulation is secured correctly. Like we said before, aluminum tape or zip ties are a great way to secure insulation material around your duct.

Special Considerations

Whether you are installing a new duct for your fan or just insulating it, there are some things to consider when doing these tasks.

Always Wear Gloves (And Maybe a Mask and Goggles!)

Your exhaust duct is in the attic, and we all know that there are dangerous things up there. Aside from the potential for splinters, it’s usually pretty dusty. But most of all, there’s a bunch of that usually pink attic insulation, which often contains fiberglass.

If you don’t touch the insulation, usually it won’t be a problem, but you never know when you might lose your footing and make contact on accident. The tiny pieces of fiberglass in that insulation can lead to small but dangerous cuts, and that’s to say nothing about what might happen if you breathe it in or get it in your eyes.

Even for a job as simple as insulating your bathroom exhaust duct, safety gear is highly recommended.

Use the Shortest Run You Can

The longer the duct is, the higher the chance of condensation pooling within it, which is what you’re trying to avoid. Try to ensure that your duct is as short as it can be.

Make Sure the Duct is Tightly Connected at Both Ends

A loosely connected duct has its overall insulation abilities compromised. Make sure it’s tightly secured at both ends!


To summarize everything, we’ve put together this little list:

Locate your exhaust duct in the attic (wear safety gear when you’re up there!)

Make sure the duct doesn’t have interior insulation

Make sure it’s as short as possible and tightly secured at both ends

Choose insulation material with an R-value between 3 and 6

Wrap the insulation around the outside of the duct

Pinch all seams closed and secure insulation with aluminum tape or zip ties

And that’s just about it. Follow these simple steps, and you can have your exhaust fan insulated in no time!