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Is it ok to vent a plumbing drain on the outside if the house was built without a plumbing vent?

Have you ever been to someone’s home and smelt a funny smell all around the house? Unfortunately for them, it could be because of the faulty vent for the plumbing drain or maybe because they do not even have one!

Usually, older structures from the 90s tend not to have a vent for the drain system. This can cause several issues in the house like the gurgling sound, unpleasant odor, and slow drainage. This article will help you decide what your next best step should be in case your house does not have a plumbing vent.

Everest Plumbing May 07, 2024
Is it ok to vent a plumbing drain on the outside if the house was built without a plumbing vent
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Can you vent the plumbing drain outside the house?

Different places have different rules and regulations regarding the plumbing drain vent outside the house. Vents for plumbing drains are extremely important to maintain atmospheric pressure in the drainage system

The vent for the drains is usually directed towards the roof of the house. But what happens when your home does not have an inbuilt plumbing drain vent? 

Some places have a building code that does not allow them to build the vent outside the house, but if you’re in Canada, the building code allows you to have a vent that runs outside the house. You just need to make sure that it is protected from frost.

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Where should a plumbing vent be located?

  • Vertically on the roof:

Most of the plumbing vents are usually located on the rooftop. The internal vents all connect and the air is exhausted from the vertical pipe on the roof.

  • Horizontally coming out of the external wall:

The horizontal length is limited, but it is not very unusual to have a vent that is horizontal and coming out of the external wall. It happens when the vent cannot be lined vertically because of some obstruction of the way.

  • Away from the window:

One of the major reasons for installing a plumbing vent is to keep the odor out of the house. If the opening of the vent is near your window, it goes against one of the main reasons why these vents are built. 

So, make sure to show your plumbers where the windows in the houses are located, just to be sure.

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What can be an alternative to having no plumbing drain?

If you do not have an inbuilt plumbing drain, you can get an Air Admittance Valve. What this valve does is that it equalizes air pressure in the plumbing system. However, you should note that this is not a long-term solution. 

Is building a vent outside the house as good as the inbuilt plumbing vent?

Exposure to external calamities

Vents outside the house are directly exposed to external calamities like extreme heat and storms. This makes them prone to damage from fallen branches or strong winds. In case of protection from natural calamities, indoor vents may be more lasting.

Exposure to frost

Extreme cold can cause some serious damage to the vent. The frost and snow around your external vent can complicate the vent system. So indoor vents have a longer life than outdoor vents.

Ease of maintenance

It is easiest to repair and maintain vents that are outdoors and exposed. This will save you both time and money. You won’t have to deconstruct your walls just for your routine maintenance.

Easy to spot the problem

The outdoor vents make it easier to spot the problem because, well, it is exposed. The indoor vents would require you to call in plumbers so that you know your vent is not acting the right way. But, when it comes to external vents, it is easier to figure out where the problem is.

Comparison between the outside vent and inbuilt plumbing vent.

Basis  Indoor vents Outdoor vents
Exposure to natural calamities They are not exposed to the external environment except for the  They are exposed to the external environment which makes them prone to more damage.
Exposure to frost Indoor vents won’t be as affected as outdoor vents by frost.  Outdoor vents can be affected by frost during extreme cold which can cause complications.
Maintenance It is difficult to repair and maintain indoor vents because they are usually concealed. Outdoor vents are easier to maintain and look after because you do not have to dismantle your home.
Easy to spot the problem It is a little difficult and a lengthy process to find the problem with indoor vents. It is easier to spot the problem with outdoor vents because of their exposed nature.

What happens if you do not vent your plumbing drain?

Bad odor

Vents for plumbing drains help tap the gases formed in the waste drainage system. It then directs these gases outside the house so that your home is odorless and smell-free.

No one wants their home to smell nasty, it is both unpleasant and embarrassing.

Slow drainage

Slow drainage is another sign of not having an airway for the plumbing system. A vent for your plumbing drain is required so that your bathroom and sinks drain smoothly.

If you do not have a vent, it is sure to increase the amount of time your shower takes to drain the water. The air trapped slows down the drainage which is when the vent comes in handy.

Gurgling sound

A proper drainage system is not supposed to make any sounds. If you do not vent your drainage pipe or if there is some problem in the vent system, you will hear a gurgling sound when you flush. 

This sound is produced when the air trapped in the drains cannot escape. Even if your toilet flushes smoothly but it produces this sound, you should call for professional help to see what is wrong.


It does not matter if you have a very old home, you should get your plumbing drain vent installed. As the saying goes ‘Stitch in time, saves nine’, getting a vent installed now, will save you a lot more in the future, both time-wise and cost-wise. 

It will give your home a balanced atmosphere making your home very welcoming and pleasant. If you know someone who could use a plumbing drain vent but is adamant about not getting one because ‘it is working just fine for them’ or their ‘home is too old and does not have one’, send this article to let them know about the benefits of vents.


What happens if there is no plumbing vent?

If there is no plumbing vent in your home, then you may hear a gurgling sound when flushing, slow drainage, and frequent clogs.

Do plumbing drains need vents?

Yes, plumbing drains need vents to ensure smooth drainage of the water.

What is one important rule about drain vents?

The vent must be as close as it can get to the fixture, preferably 5-6 feet away from the fixture.

Can you vent the plumbing outside the house?

Yes, you can vent the plumbing of the drains outside the house. If you’re talking about the vent built outside, you’ll have to check in with the building code of your area.

Are cheater vents legal in Canada?

No, they are not legal and they are not in the code as well.

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