Learn how to clear a clogged vent without risking life and limb
Drains that gurgle and take forever to empty, foul sewer odors in the house, and toilet tanks that mysteriously run dry all point to one culprit–a clogged plumbing vent. This integral part of your home’s plumbing system, sometimes called a plumbing vent stack, is responsible for regulating the airflow, keeping the water flowing through drains while venting foul sewer smells. While a plumbing vent often needs little to no maintenance, sometimes they can become clogged with debris, leaves, and even curious wildlife. You can risk life and limb and climb on the roof to fix the problem, or you can follow one of these less risky methods to unclog a plumbing vent without getting on your roof.
While the only way to clear a clogged vent may be to climb on the roof, doing so is dangerous, especially if you need to haul equipment up with you. Before getting a ladder out, try these alternatives first.
All of the drains in your home lead to a large drain called the main stack. This large drain pipe not only carries wastewater to the curb and the city sewer or your septic system (if you’re not on city sewer), it also functions as a vent for the plumbing system. The main stack extends from under your house up through each floor of the home, including the attic, before venting through the roof. You can access that vent pipe by heading to the attic.
Once you find the vent in the attic, cut a piece out of it using a hacksaw. You don’t need to make a large cut, as the hole only needs to be big enough to allow you to thread a plumbing auger into it. Insert the auger into the vent so it heads downward until you feel it push up against the clog. Crank the handle on the auger to chew the clog out. Once you’ve cleared the clog, you’ll need to repair the pipe using PVC coupling.
When clogged vents cause problems in the winter, snow and ice often collect over the roof vent opening, preventing proper airflow. Don’t attempt to climb on a snow-covered roof to clear the vent. A safer alternative is to melt the snow from the inside out.
There are several ways you can accomplish this:
Hot water: Running hot water creates steam and heat that rises through your vent pipe. Turn on a faucet on the uppermost floor of your home and allow it to run hot water for a while. The heat the water creates may be enough to melt any snow or ice that’s clogging the vent.
Hair dryer: Head to the attic with a hair dryer. Use it to direct warm air on the vent pipe as close to the attic ceiling as possible. The hair dryer will transfer enough heat to the pipe to melt the snow without causing damage to it or creating a fire hazard.
Heat tape: Despite its name, heat tape isn’t tape at all. It’s actually an electrical cable that creates a small amount of heat. While it’s mainly used to keep water supply lines from freezing in the wintertime, you can also wrap it around a plumbing vent pump in the attic to warm it and thaw any ice or snow that’s clogging it from the roof.
Though climbing on the roof is dangerous, it’s the most direct way to clear a clog and your only alternative if the above methods fail. Remember that climbing on the roof involves risk. If you have a roof with a steep slope or simply don’t feel comfortable doing it, the risk isn’t worth the cost of hiring a licensed plumber to handle the job.
If you decide to attempt this repair yourself, take precautions by wearing footwear that will allow you to get good traction on the roof and have a helper on hand to assist you with the ladder.
You’ll need to bring a screwdriver in case the vent has a cap you need to pry off. Once up top, examine the vent to see if you can ascertain what’s causing the clog. It may be as simple as clearing debris or a bird's nest. If the clog isn’t visible and easily accessible, you’ll need to resort to other methods.
Water: Bring a garden hose with an adjustable nozzle onto the roof. Set the nozzle to a narrow high pressure spray. Direct the spray down into the vent to clear away any clogs. If the water backs up and comes out of the pipe, you’ll need to take more drastic measures to clear the clog.
Plumber’s snake: Bring a plumbing snake or auger onto the roof. Run it down the vent until you reach the obstruction. Turn the crank on the plumbing auger to cut through and remove the clog.
It’s easy to misdiagnose a clogged vent as a clogged drain. Luckily, there are a number of ways to tell if it is indeed the plumbing vent without having to scale a ladder.
Slow drains: When debris is clogging the plumbing vent, it won’t allow air inside to help push water out of the drains. As a result, it will take longer for all the sinks and tubs to drain. A clogged plumbing vent is likely the culprit if you have multiple slow drains in your home.
Gurgling noises: If your toilet makes an odd gurgling noise when you flush it? Do the sink drains make a glugging noise as the sink empties? These sounds are signs that air can’t escape your plumbing system because the vent is clogged.
Sewer odors: A plumbing vent allows sewer smells to escape your home. Those gases can build up and eventually leak into living spaces when its clogged. Sewer gases can be more than just unpleasant; they can also be toxic, so don’t delay if you detect these sewer odors.
The best way to deal with a clogged plumbing vent pipe is to prevent it from getting clogged in the first place.
Screen: Install a screen or filter over the top of the vent pipe to prevent debris from falling in the vent or animals from crawling inside.
Pipe insulation: Wrapping the pipe in foam insulation can help it retain heat, preventing snow and ice from forming on top of it.
While clearing a clogged plumbing vent isn’t complicated, it can be potentially dangerous depending on the lengths you must take to fix the problem. The best approach when dealing with this issue is to try easy fixes first by attempting to clear the clog from the attic. If this fails, determine how risky it is to attempt to move the clog from the roof yourself.
Consider the pitch of the roof, how high it is off the ground, and how difficult it will be to haul equipment such as a garden hose or plumbing auger up to the vent. If the job is too dangerous, hire a pro to take care of it.
If you decide to hire a licensed plumber near you to handle the fix, you can expect to pay between $150 and $200 for this service, although it could be more depending on the severity of the problem.
To unclog a plumbing vent, you first need to locate it. Look at your home's roofline. The plumbing vent will be a vertical pipe sticking straight up from the roof. Since this pipe runs all the way to the main drain underneath your house, you should also be able to find it in the attic.
Yes, you can snake a roof vent. This is one of the best ways to clear a problematic clog in a plumbing vent. You can either snake the vent by climbing on the roof and sending the plumber’s snake or auger directly down the vent opening, or you can cut a hole in the vent from inside the attic and snake it from there.
Pouring drain cleaner down a vent pipe isn’t recommended. First of all, unlike a clog in a sink or bath caused by such material as soap scum build-up, toothpaste, and hair, clogs in a vent pipe are likely the result of debris from trees or even an animal stuck in the pipe. Drain cleaners won’t be able to eat through this kind of material. The cleaner will only become clogged in the vent with the debris, causing even more problems.
To keep your plumbing vents from freezing, start by insulating your pipes with foam or fiberglass sleeves to help maintain their temperature. For an extra layer of security, use heat tape, which acts as a personal heater to keep your pipes warm even when temperatures drop. Additionally, you should regularly check your vent cap to make sure it’s free from leaves and debris that can block the airflow. A clean, unobstructed vent cap is crucial for maintaining proper ventilation that will keep your plumbing vents from freezing and the plumbing system running smoothly.
