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Dryer Vent Leaking | Reasons & Solutions

Dryers are supposed to dry things, not leave puddles on your floor for you to wade through. Water that stands on your flooring is a nuisance. It’s also a slipping hazard and can damage and stain the floor surface.

You are not the first to have a problem with a leaking vent, and there are several possible reasons why your dryer vent is leaking. I have compiled this list to help you figure out what the issue is and to solve the problem as quickly as possible. So, say goodbye to cleaning up puddle after puddle!

Dryer vents can leak if there is insufficient insulation, improper ducting, or blocked ductwork. A vent can also leak if there is a problem with the backdraft damper. Adding insulation, correcting or clearing out the ductwork, or repairing or replacing the damper should solve the issue.

No Ductwork Insulation

A lack of or insufficient insulation for the dryer vent ducting can cause leaking from your dryer vent. This is due to the condensation that can form inside or outside the ductwork without insulation. Both of which will result in water dripping from the vent.

A dryer channels hot air (which has good water retention) into the drum, where it soaks up the moisture in your clothing. Dryer vents are intended to remove this hot and humid air from the appliance and exhaust it outside.

The problem is that condensation occurs when that hot air meets the cooler outside air and can no longer hold the same quantity of water as it cools. This is especially problematic for the very humid air that is exhausted from a dryer or the bathroom.

When the air loses its capacity for water content, droplets form, and you are going to have a leaking vent.

Process of condensation inside the vent dryer

If you’re interested in a more scientific explanation of how this happens, you will find it in my article on why bathroom fans drip.

So, you need to protect the vent and keep the air of differing temperatures separate until it reaches the outside and can mingle and condense without creating trouble for you. This is why it pays to ensure that you install the ductwork with proper insulation.


If your insulation is the problem, then fixing the leak is as simple as adding or replacing insulation on the dryer duct.

Insufficient insulation can be a result of too little or old insulation. Of course, you will experience condensation issues if there is no insulation at all.

You need to make sure you have good quality and the right kind of insulation that is well-fitted on the ducting so that it can properly function.

You may choose to call an expert in for this job, as it is not as easy as it may sound to get the insulation to sit snuggly around the ductwork, and they will be able to make sure everything is correct.

Improper Ducting

Insulation is not the only thing that can be wrong with the ductwork; the leaking can also be a result of a problem with the ducting itself. There are several areas to look at when it comes to ductwork. Its length, straightness, and inner surface all play a part in preventing or causing leaking.

If the ductwork is too long, has too many bends, or has a ridged inner surface, then it interferes with the flow of air to the outside.

Man tightening the lock for the ducting of the vent dryer

When ducting has features such as these, some moist air will remain in the ducts for too long and will cool. This will inevitably result in condensation as the air cannot hold all the humidity. The condensed water will run back down the dryer duct and out the vent when it cools.

Excessive bends or a textured surface in the ductwork will also encourage lint to build up in the ductwork, which will cause blockages that can result in leaking. A duct that is too long and bows will also promote blockages.

Aside from the above causes, leaking could also result from cracks or holes in the ducting. These interfere with the airflow. It is also allowing condensation to leak out at those sites.

Too many bends, a ridged inner surface, and an excessively long ducting path all contravene the International Residential Code requirements for venting dryers.


You should consult the manufacturer’s recommended duct length for the dryer. It is possible to shorten the ducting for the appliance by cutting it or purchasing a shorter piece of ducting, but I would suggest you consult with a professional for advice if you are unsure.

You will have to replace the ducting with a more suitable material that has a smooth inner surface or if the ducting has become damaged or warped and is no longer straight.

If the vent is leaking water because the duct is cracked or has a hole, you will need to replace the duct to fix the problem properly. Any other solution to a hole or crack in your vent is only temporary and will likely require repeated sealing.

It is worth considering that you might need to hire a professional to make modifications to the ducting for the purpose of appliance warranties.

Blockages in the Duct

Even if the ductwork has been laid properly, blockages can occur. If your clothes have started coming out still damp, this is a good indication (along with standing water) that your dryer vent is clogged.

In a dryer vent, the most common culprit is dryer lint. Lint is the fine fabric fibers that come off your clothes when you dry them. It can easily build up in the vent and at the exits. Dust can also be deposited in the vent in the form of gunk.  

If you are the type to forget items in your pockets, you may need to inspect your dryer vent for the misplaced gum wrappers, paper, and bits of tissue can also clog up the vent.

Hair is also a potential, both yours and your pets’. I have a fluffy dog, and his fine hair gets everywhere and on everything.


You can remedy a blockage issue by clearing out the dryer vent. It may end up being a little mucky, but you should be puddle-free.

In order to prevent lint from building up and blocking the vent, you should regularly clean out the vent and the dryer’s lint trap. The lint trap is supposed to catch as much lint as possible, which will help prevent too much from entering the vent. However, this function is impaired when the trap is overly full.

Man holding a lint trap full of lint from the dryer

Cleaning out lint from the dryer vent also helps decrease the risk of fires starting as it manages the amount of lint in your house’s environment by lowering the amount of lint that can blow back into your home through the vent.

Broken Ducts

Broken ducts allow air to escape into other spaces, reducing the pressure in the ducts. This affects velocity pressure, which is what moves the air along the ducts. Thus, a broken duct can result in air remaining inside the duct longer than it should.

Then longer the air spends in the ducting, the more time it has to cool down. Moisture is condensed out and is free to drip back down to the dryer.

There are also a number of dangers linked to broken ducts, like rot, mold, carbon monoxide poisoning, and lint fires.


The solution to a broken duct is to replace the broken section (patching is not an effective method). You can do this yourself, particularly if the issue is with the transition duct, or you can hire a professional. Good options include a general contractor, an HVAC specialist, or even a roofing specialist.

Faulty Backdraft Damper

A backdraft damper is like a one-way valve, allowing air to flow from ductwork to the outside, but sealing against air entering the ducting from the outdoors.

The backdraft damper on the dryer vent is, like insulation, essential in keeping the outside air and air from the dryer separate while it is in the ducting. If your backdraft damper is faulty, this can result in condensation in the ducting and leads to the dryer vent leaking.

A backdraft damper can be faulty due to several reasons:

  • It is the incorrect size for the vent.
  • It is incorrectly installed.
  • Parts of the damper have become damaged, worn, or blocked.
  • It is a manufacturing fault.

All of these reasons can impact the airtightness of the damper, meaning that it isn’t functioning as intended and is affecting airflow out of the vent or allowing cooler air into the vent. Both scenarios will, of course, result in condensation and leaking from the dryer vent.

You may also notice a cold draft or a noise coming from your dryer if there is an issue with the backdraft damper.

This is often a bigger issue with dryers that are vented through the roof because rain and snow are more likely to enter the vent.


If it is a manufacturing fault, you have likely installed a new backdraft damper recently and can return the product for a replacement or refund. So, let’s look at the other issues.

It should be easy to diagnose an incorrectly sized damper as whoever installed it would have made some modifications to connect the vent output to the damper. Tape, excessive silicone sealing, and the noticeable mismatch between damper and vent are all signs that you should be replacing your damper with one that fits.

If your damper’s flappers open inward, it has been incorrectly installed. This is often a simple matter of cutting out the silicone seal, cleaning the damper and the vent, and resealing the damper back into the vent in the correct direction.

Seals are the only damaged parts of the damper that can be removed and redone. Mold on the seals or a lint buildup can block the flappers from functioning correctly. Replacing the seal with a mold-resistant caulk will help, and regularly clearing the lint will prevent future troubles.

Gorilla Waterproof Caulk & Seal 100% Silicone Sealant, 10oz Cartridge, Clear (Pack of 1)
  • INDOOR/OUTDOOR: All Weather

Last update on 2023-06-10 / Affiliate links / Images from Amazon Product Advertising API

Any of the mechanical parts, like the flappers or electrics, are likely going to require a new damper. You can call out a professional to see if repairs and replacements are possible, but this is not guaranteed.

AC Infinity 4" Backdraft Damper, One-Way Airflow Ducting Insert with Spring-Loaded Folding Blades for 4” Ducting in Range Hoods and Bathrooms Fans
  • An antidraft duct insert designed for use with range hoods, bathroom fans and other home HVAC applications.
  • Features outer rubber gaskets that create an airtight seal and grip between the damper and ducts.
  • Mounts horizontally or vertically to prevent backflow and debris from entering ducting.
  • Galvanized steel body with spring-loaded aluminum damper blades that open with minimal airflow.

Last update on 2023-06-10 / Affiliate links / Images from Amazon Product Advertising API


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