I am so pleased that I’m not the only one who is suspicious of these kits. They sound too good to be true—retaining the benefits of a vented dryer without having to cut holes in your house or lay ductwork? What a dream!
Here’s the rub—it’s just a dream. Indoor dryer vent kits are little better than simply letting your dryer exhaust unobstructed into the room. Let’s look at what different countries have to say about indoor venting of dryers.
Indoor dryer vent kits filter lint but release hot, moist air indoors. In the USA and Canada, venting dryer exhaust indoors is against the code. Codes in the UK, Europe, and Australia, don’t mention indoor dryer venting. But venting indoors goes against manufacturer instructions and is unsafe and unhealthy.
Although indoor dryer vent kits are openly sold in stores, it’s mandatory for dryers to exhaust their air to the exterior of the home. But who says so? Well, this is actually a regulation in the International Residential Code (IRC).
Section 1501.1 of the IRC states:
“The air removed by every mechanical exhaust system shall be discharged to the outdoors in accordance with Section M1504.3. Air shall not be exhausted into an attic, soffit, ridge vent or crawl space.”
“Every mechanical exhaust system” includes dryers and the necessity of outdoor termination of the exhaust is further solidified in Section M1502.3, which talks about dryers specifically and states:
“Exhausts ducts shall terminate on the outside of the building.”
Simply put, indoor dryer vent kits are not up to code in the USA, where the IRC is applicable.
The hot, humid air expelled from a dryer’s exhaust can lead to structural damage and lower the air quality in your home. Also, the exhaust carries excess lint that can mold and when dried out, present a fire hazard.
Similar to the building codes in the United States, indoor dryer vent kits are not allowed in Canada. Section 18.104.22.168. (19) of The Ontario Building Code states:
“Exhaust ducts or vents connected to laundry-drying equipment shall discharge directly to the outdoors.”
There are no exceptions to this code. Any dryer not venting to the exterior is in violation of the building code.
While violators of this code aren’t going to receive severe punishment like being arrested, it is illegal to break building codes. There are fines and other punishments associated with doing so.
Code violations aside, a dryer venting indoors presents potential problems that can adversely affect your health and the structural integrity of your home.
At best, indoor drying vent kits will serve as a lint catcher, still allowing the hot, humid air to build up. Hot and humid air can seep into the walls and structure of the home slowly breaking it down. Pests are also very attracted to the warm and moist environment.
UK and Europe
Unfortunately, I was unable to locate/access the building codes that specifically regulate vented dryers in the UK and Europe. This is most likely due to the fact that the use of vented dryers in European countries is far less common. Most people tend to have ventless models.
This is not to say that vented dryers are not used at all, only that it’s less common and, therefore, the building code is broadened in order to keep it less dense and uncomplicated. The regulation of venting a vented dryer will fall to the manufacturer.
Then there are some countries, like Switzerland, which have essentially banned the use of vented dryers due to their high consumption of energy. The introduction of minimum energy performance standards has encouraged consumers to spring for a “greener” model such as those powered by heat pump technology.
Much like the case for the UK and Europe, I am unable to access the building codes in full that would (or would not) specify regulations regarding venting dryers.
However, there is information that hints that while it is not a legal requirement, dryers should be vented to the outdoors
I’ve seen many product and supplier sites that highly recommend that dryers be vented outside. For example, Pacific Air Industries says this:
“Whilst not legally required in Australia, we strongly recommend venting out your vented dryer to enjoy a number of benefits. Each time you use your dryer, you are putting several kilograms of moist air into (what is usually) a small room. This has a number of implication unless the air is vented externally.”
It should also be noted that some governments have certain safety regulations that require the instructions of manufacturers to be followed. The Queensland government is an example of this.
This requirement by the Queensland government inadvertently requires dryers to be vented outside as most dryer manufacturers recommend this to their consumers.
Aside from the guidelines of manufacturers, Australia does require laundry rooms themselves to be ventilated. This is due to the large amounts of humidity produced by a vented dryer.
Although it would be better to vent the dryer outdoors, as long as 40 L can be extracted from the room and the manufacturer has no rule against it, indoor venting, and by extension, indoor dryer vent kits, are allowed.
Why Indoor Dryer Vent Kits Are Not up to Code
Indoor dryer vent kits, in most instances, are not up to code or at least discouraged for a variety of reasons.
One of the primary reasons they are not allowed is because of the humidity produced. For the most part, dryers are located in smaller rooms allowing for less natural ventilation and more build-up of humidity. This humidity can leave serious structural damage.
Exhaust from dryers also contains lint—a lot of it. Some of it is caught by the indoor vent kit, but not all. While the lint is still moist can lead to mold, which can cause health issues and ruin the structural integrity of a home as well as the insulation. When the lint dries out, it gets carried around in the air of your house. If dry lint builds up, you’ve got a fire hazard on your hands.
Depending on the location of your laundry room, you may even have a pest issue. Warm places with plenty of moisture are a perfect environment for critters.
Some critters, like mice, become a serious problem when they get their teeth into wires, support beams, and insulation. Termites are another type of pest you don’t want to invite into your home because they’ll only make the rotting wood decay faster.
Anybody using a gas dryer should never vent inside their home. Adding an indoor dryer vent kit into the mix makes zero difference to this.
Gas dryers are burning propane or natural gas to generate heat, which gives off carbon monoxide. Over time this could lead to serious respiratory problems as breathing carbon monoxide can be lethal.
For more information on the health and safety risks associated with these indoor dryer vent kits, you can read my article: Are Indoor Dryer Vent Kits Safe?
Prohibited Even if the Dryer Is Electric
While an electric dryer doesn’t burn natural gas or propane, it still is not safe to vent indoors, even with the indoor vent kit attachment. Just like a gas-burning dryer venting indoors can lead to health problems, so can an electric one.
It doesn’t give off carbon monoxide gas but an electric dryer still gives off a ton of humidity and lint in its exhaust. This combination leads to mold which, left unchecked, leads to contaminated, moldy air particles floating around your house.
What If the Dryer is in the Middle of the House?
Sometimes, the location of a laundry room becomes an issue for properly venting a dryer. Laundry rooms located more centrally in the house make it difficult to install a ventilation system that is up to code. Although it’s difficult, it’s still possible.
There are ways to utilize adjacent rooms and run vents through the bulkheads to vent a dryer in the middle of the house. However, this takes time and money that not every consumer is willing to spend.
An alternative is to consider a ventless dryer. This will eliminate the installation process of snaking ducts through and around rooms. They may cost more than a vented model, but the costs tend to even out once you see how much you’ll be paying in addition to a vented model.