How To Insulate The Dryer Vent

An uninsulated dryer vent and vent pipe will attract condensation which leads to mold and other moisture issues. Knowing this, you are likely wondering how to insulate the dryer vent. Well, in this post we combine industry professional knowledge and up-to-date research to answer your question.

There are several ways to insulate a dryer vent. However, the cheapest and easiest way follows these general directions:

  1. Locate and gain access to the entire vent
  2. Gather all materials
  3. Wrap vent with batts and tape
  4. Twine batts in place

Keep reading the rest of this post for more details on each of the above steps. This guide is all you will need to ensure that your dryer vent is well insulated for years to come. To conclude, we'll answer a few questions related to the topic of this post. Without further ado, let's get into it!

Removing lint from the dryer vent, How To Insulate The Dryer Vent

How To Insulate The Dryer Vent

The goal of insulating the dryer vent is essentially to distance the hot vented air from the cold spaces that the vent is traveling through. Without the insulation, the cold air will condense water on the outside of the vent while the vent is hot.

According to the Environmental Protection Agency, this moisture can lead to harmful mold and mildew and even home structure problems. Often, dryer vents are insulated prior to condensation being an issue. However, it is also common for this step to be taken only after dryer vent condensation is noticed.

Technician inspecting the dryer vent for any damages aside from lint deposits

Remember, condensation only occurs when different temperatures interact. Therefore, if your dryer vent travels through conditioned interior space (like a heated basement) there is no real advantage in insulating the vent.

1. Locate And Gain Access To The Entire Vent

The first step to insulating your dryer vent is to gain full access to the part of the vent in an unconditioned space. Often, this involves entering and working in cramped and unpleasant crawl spaces. When entering crawl spaces, be sure that the space is safe, and wear eye, breathing, and body protection.

Click here for eye and breathing protection from Amazon.

The start of the dryer vent is obviously at your dryer, and then the end terminates at a vent opening that you can usually locate on the outside of your home. Here, we are concerned with the vent piping between these two points.

At this step, take the time to remove any cobwebs, debris, and other obstructions that will get in the way of wrapping the vent duct. Taking the time to specifically clean the space out first is well worth the effort given how tight this job often is no matter the circumstances.

Also, be sure to measure both the diameter and the length of the vent that you are trying to wrap. This will be very helpful when it comes time to buy the materials.

2. Gather All Materials

For this job, it is best to use fiberglass batts that are faced with a vapor barrier material. Often, this comes in the form of either foil, Tyvek, or another similar facing.

Click here for faced insulation from Amazon.

The vapor barrier character helps to ensure that no moist air can get into your batts. This air would damage the insulation and cause the moisture problems we are working to solve with this project in the first place.

Buy enough batting to cover the entire square footage of the vent's outside. Generally, any R-value from R-11 to R-19 is sufficient for this insulating job. Also, purchase twine and seaming tape.

It is not advisable to use duct tape or other household tapes. Unfortunately, these tapes do not function as effective vapor barriers and often lose their adhesion over time.

Click here for seaming tape from Amazon.

Both of these factors will lead to your carefully installed insulation falling off the dryer vent and moisture condensing against the vent piping. The takeaway here is that the extra cost of high-end seaming tape is well worth the extended project lifetime and quality.

3. Wrap Vent With Batts And Tape

Now, wrap the batts around the vent. Simply wrap them in a perpendicular manner so that they butt up perfectly square. At this butt, tape them firmly in place. Also, tape the terminating end of the batt to whatever building elements are nearby.

When wrapping and taping the vent, try to keep the batt in full contact with the vent without being compressed at all. If you fail to do either of these things, the overall R-value will be reduced. Read the subsection at the end of this article to learn how to easily cut batts.

Now, wrap the next section of batting in place immediately following the first. In addition to taping the batting to itself, you will also need to tape the seam where the two batts meet together.

Continue this process for the entire length of venting in unconditioned space. Remember, the more careful you are with your taping job, the more effective and long lasting your insulation job will be.

4. Twine Batts In Place

For extra holding power, it is now wise to twine the batts in place. Wrap the twine around the insulated vent. Periodically tie the twine together. You can also sinch the twine onto itself to create a solid wrap around the entire vent.

Click here for twine from Amazon.

Remember, it is once again important to create a snug fastening without compressing the batts too much.

This step, while tedious and apparently unnecessary if you did a good job with your tape, will help the entire assembly keep its insulative power and shape over time.

How To Cut Fiberglass Batts

Fiberglass insulation on top of the house plan

Insulating a dryer vent requires that you make very straight cuts in the ends of your batt. To accomplish this, follow these directions. In general, these steps work for cutting fiberglass batts in any situation. Use a standard utility knife or another sharp knife for this job.

1. Set Up Cutting Area

It is essential that you have a hard surface that you do not mind scarring with a utility knife blade. Usually, this is a piece of scrap plywood or plywood that will not be visible once installed. Also, you will need a straight edge that is at least as wide as the fiberglass batts. A 2x4 works well.

2. Prepare To Make Cut

Now, measure the batt so that it perfectly wraps around the vent pipe. Place your hard straight edge at this measurement so that you can draw your knife straight along the measured point.

3. Make Cut

Now, press down on the straight edge onto the cutting surface. This will compress the batt enough so that the blade of a utility knife will pass all the way through. Draw the knife along the straight edge, cutting the batt completely and cleanly along a single line.

How Do I Stop My Dryer Vent From Getting Cold Air?

Inspecting the dryer vent after cleaning it

The best way to stop a dryer vent from getting cold air is to install a louvered damper. These are designed to only open when air is being blown from the dryer. This way, no cold air can sneak up your dryer vent into your home.

Click here for a louvered dryer vent cover from Amazon.

Can A Dryer Vent Touch The Wall?

Yes, that is not an issue. The dryer vent will not get very hot compared to the wall materials. It is very common for the interior part of dryer vents to be pressed up against the back of the dryer, the floor, and the wall.

Can You Use A Flexible Foil Duct For A Dryer?

Installing a brand-new dryer vent

Yes, you can. Flexible foil ducts are the go-to dryer vent material for immediately behind the dryer. Their flexible nature is essential for connecting the variable dryer outflow location to the built-in vent location in your home.

However, flexible ducting is not advisable for long straight runs in basements or crawl spaces. Flexible ducts will sag. These sags are choke points that will build up dryer lint which can cause your dryer to work less effectively, and they are also potential fire hazards.

Can You Put A Dryer Vent Behind Drywall?

It is possible to put the dryer vent behind the drywall. In general, this will not break any code regulations. However, the dryer duct needs to be quite thick, which means it might not fit in a standard wall.

Further, it is wise to check with your local building department about whether this unusual configuration is allowed.

In Closing

Removing lint from the dryer vent

In this post, we covered how to insulate a dryer vent. These step-by-step directions are all you need to accomplish this task. To conclude, we answered a few questions related to this post. Good luck!

To learn more about dryers and insulation, read these articles:

Dryer Won’t Start But Has Power – What To Do?

Kenmore Elite Dryer Won’t Start – What To Do?

How To Insulate A Garage Ceiling

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