Learn What Plumbing Vent Pipes On Roof Are For (2023 Guide)
The pipes that penetrate the roof are plumbing vents. The plumbing vent, also known as a vent stack, helps regulate the air pressure in your plumbing system. Just as drain pipes remove water and waste from your home, the plumbing vent pipe – also known as a plumbing air vent – removes gas and odors. The vent stack is the pipe leading to the main roof vent.
I recently inspected a home in Miami, FL where this was a discussion. This was a beautiful home with 3 bedrooms, 3 bathrooms, and lots of remodeled areas in the home such as the flooring, kitchen, roof, electrical, and HVAC systems. This home had a slab foundation, so much of the plumbing was concealed but there were some things that didn’t quite function as expected which prompted me to recommend a sewer scope inspection be performed such as:
- Old piping observed in use for the shower stall – cast iron
- slow drainage one of the bathrooms
- slow drainage in the kitchen sink
- incorrect drainage for piping in the laundry room for appliances
Those were some examples of things that were called out for plumbing to the buyer, buyer’s realtor, and the selling agent who was the owner as well. Everyone was working together well. Communication is key in any real estate transaction and sometimes not valued enough. Shot out to those that put communication as a priority.
So what did the plumber find when they inspected the property?
Looking at the first item “Vent Kitchen Sink”, the plumber found while performing their sewer scope inspection that the kitchen is draining into the mainline with no vent. This is something a home inspector can not see in most cases, it’s assumed that during the original construction of the home that all plumbing lines connect to a vent pipe to allow air into the system and gases to be removed.
This home was a flip and the kitchen sink was moved from the original installation that was properly vented. When the kitchen was remodeled the sink was moved to the exterior wall and was no longer vented. Neither was the dishwasher that was attached to the sink. Could have been a stinky situation if not resolved. How do you think the new homeowner would have felt about their inspection if that had happened. Probably not too good.
Good thing the repair is not expensive, you can add an air admittance valve to the pipe after the P-Trap as noted that will allow air into the system so it can properly drain.
FAQ: Plumbing Vent Stack
How do I know if my plumbing vent is clogged?
- Gurgling and bubbling sounds, you will have these sounds when you have water flowing down the drain.
- In the event that you have a slow drain, you could be having a blocked drain.
- Do you have an odor from your toilet or drain that smells like sewage?
How to unclog plumbing vent without getting on roof?
If you need to learn how to unclog vent pipe on roof, there are several methods that can help.
The first is to use an auger or a plumbing snake. You can rent one from your local hardware store or buy one if you plan to use it more than once. Insert the auger into the vent opening, and start pushing it in. If the clog is close to the opening, you should be able to break it up with the auger. Keep pushing until you reach the clog and then continue turning in a clockwise direction until the blockage is cleared.
Another option is to use a shop vac to suction out the clog. Attach the shop vac hose to the vent opening and turn it on. The vacuum should draw out the clog, allowing you to clear the obstruction without ever having to get on the roof.
You can also use a combination of water pressure and air pressure to push out any debris blocking the vent pipe. Connect a garden hose to a pressure washer, and then use the pressure washer to direct water up into the vent pipe. As you do this, blow compressed air from an air compressor down the same pipe. This will push out any debris that may be blocking the passage.
Finally, if all else fails, you can call in a professional.
Should roof vent pipe be covered?
The answer to this question depends on the type and location of your roof vent pipe. Generally, if the vent pipe is in a place that is exposed to outside elements, it should be covered with flashing or some sort of weatherproof material. This will help protect it from the elements and keep moisture out of the attic space.
How many vent pipes can be installed?
There can multiple vent pipes on roof. It will vary by the home and or building plumbing system needs.
How should vent pipe be installed? Here is an example of a toilet fixture being vented.
Click here or watch below.
The horizontal vent pipe runs right next to the closet bend. If the vent wall is parallel to the drainpipe, install a 45-degree reducing Y and a street elbow to point toward the wall. You might need another elbow (of any degree) to position the vertical vent where you want it. The International Plumbing Code (IPC), requires plumbing vent pipes to extend vertically at least 152 mm (6 in.) above a roof, per Section 905.5, “Vent Connections and Grades.” Additionally, vent pipes must be at least 305 mm (12 in.) away from a vertical surface.
I hope this information has been helpful in explaining the purpose of our plumbing vents and how they work. If you have additional questions and want to get in contact with GGR Home Inspections please send us a note, text, or call.
Pingback: How To Fix A Ceiling Crack Forever (2023 Guide)
Pingback: Do Cast Iron Pipes Fail 4 Point Inspections? - GGR Home Inspections
Pingback: Vent Stack vs Stack Vent; Learn What They Are (2023 Guide) – GGR Home Inspections
Pingback: Don't Flush Your Money Away: The Value of a Sewer Scope Inspection - GGR Home Inspections