Why You Need a Well-Maintained Plumbing Roof Vent on Your Home

Brick house with a white garage door and grey shingled roof. The top of the house has a small plumbing roof vent.

A plumbing roof vent is an incredibly important part of your home’s plumbing system. However, few of us have probably thought much about them. In fact, I did not even know such a thing existed until I had an unfortunate plumbing disaster of my own doing at home. Long story short, I redid my plumbing and made an amateur mistake; I did not put a roof vent on. The result was not good. My bathroom smelled like someone died in it and my plumbing kept clogging. I called a professional and, to his credit, he tried really hard not to laugh at me.

Aside from the plumbing problems that are caused if you do not have a plumbing roof vent, an old, degraded one can also cause some serious roof problems. These roof leaks are very common but left unchecked they can cause serious structural damage to your home.

So, why are these vents so important? How would you even fix issues that arise? A small amount of information can save you from experiencing a plumbing disaster like me.

What is a Plumping Vent?

A plumbing roof vent, also known as a vent stack, removes gas and smells from your house. The system, which has two parts, also helps regulate the air pressure in your plumbing system. The roof vent and drainage work hand in hand, keeping your plumbing healthy.

For instance, when you flush your toilet, fresh air that has entered your plumbing pipes from the plumbing roof vent will help move water through your system. This pushes the waste into the drainage pipes which then carries it to your septic tank your city sewer. When this system gets messed up the plumbing stops functioning.

If this happens you will notice that your toilet is not flushing no matter how many times you use your plunger. You may also see wastewater start bubbling up into your sinks and tub. When this starts to happen, your house will start to smell really bad as well. If that happens, call a professional plumber. They may get on top of your house and insert a snake into your plumbing roof vent to unclog the vent stack and drainage lines to get it working again.

As mentioned, the plumbing roof vent works to regulate the smells and gases produces by waste. Interestingly, since the beginning of indoor plumbing, these plumbing roof vents have been used. The following photo is a plumbing vent diagram from the early 1900s:

Basic diagram of a 1903 plumbing roof vent system.
Image Public domain, by Internet Archive Book Images, via Wikimedia

Even the earliest plumbers knew the importance of the plumbing roof vent.

Roof Leaks and Your Plumbing Roof Vent

Photo of a plumbing roof vent. It is a white PVC pipe that comes through the roof of the home.
Image screenshot via YouTube

As mentioned above, the plumbing roof vent can also damage your roof. So, on top of your roof is the plumbing roof vent. According to the plumbing vent code, the pipe extends out of the roof. At the bottom of the pipe, sitting on the roof is a vent flashing. This flashing has a rubber collar that works as a seal to keep water from getting into your home.

Over time, the rubber collar on the plumbing air vent degrades. It is exposed to all of the weather elements and the sun so it begins to crack. When it cracks, water is able to seep in between the plumbing vent pipe and the roof. This, of course, can cause damage to your ceiling and even cause mold growth. In some homes, you will have more than one plumbing roof vent and if they start leaking, each one can cause thousands of dollars in damages.

To prevent this, you want to make sure you check the flashing when you inspect your roof periodically. If you do notice that it is degrading, replace it immediately.

How to Replace Plumbing Flashing

Replacing the plumbing roof vent flashing and collar is actually pretty straightforward. If you don’t want to spend a lot of money on a roofer, you can do it yourself. Just be careful when you are on a roof. Also, remember that the pressure of someone walking across the roof may damage some of the tiles.

The first step in replacing the flashing is removing the old roofing materials around the plumbing roof vent. You can use a crowbar to remove the shingles, vent flashing, and roofing nails.

Once you remove the roofing nails, use roofing tar to seal the holes. Next, you will need to cut a hole in the water and ice membrane that’s a little larger than the diameter of the plumbing vent pipe. Slide this membrane over the plumbing vent pipe.

Further, you will need to replace half of the tiles that you removed. Place them halfway across the area that you plan to cover with the flashing. Slide the new flashing over the pipe and secure it to your roof.

Finally, you need to seal everything with caulk. Put the caulk around the pipe, where the rubber membrane is. Also, caulk the bottom of the flashing. If you used more nails to secure the flashing to the roof, caulk those nails and install the rest of the shingles.

Watch this video to see more:

Don’t Ignore Your Plumbing Roof Vent

Again, we cannot stress to you enough how important it is that you have a plumbing roof vent. If it were not for this simple invention, your plumbing would not work. Take it from me, it will be very bad. Your house will smell like death. Clogs will appear in the lines of your toilets and sinks. You will spend a lot of money on plumbing bills.

Equally as important, you need to make sure that you are properly inspecting it. Roof leaks are maddening. When your roof leaks it can cause a staggering amount of damage to the inside of your home. Yes, even a small, slow leak like one that would result from a plumbing roof vent. The good news is, however, that you can replace them with minimal effort and the right supplies.


Featured image CC0, by ArtisticOperations, via Pixabay


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