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compiler

Why does a pipe vent need to go out of roof?

compiler
12 years ago

A pipe vent goes out of my house roof. {{gwi:1434459}}

Apparently, the pipe vent collects rain and dew water. One of the pipe connector is loose, that cause leaking on my ceiling. Can you explain why the pipe vent should go out of the roof to collect the rain and dew water? What will it happen if there is no pipe vent out of the roof?

Comments (66)

  • compiler
    Original Author
    12 years ago

    Thanks for all your replies. I am learning. I took another {{gwi:1434462}} to show two stuffs on my roof. The left one seems for the air flow. It does not connect any pipe. The right one is a pipe that I am talking about. It goes down and connects to my house drainpipe. Yes, I did see the built-in flashing. But the leak does not happen in that part, the black thing around the pipe. Rather, it happens in the lower part of the pipe where it has a

    . The U connector is loosing. So water leaks. Thus, I am thinking where the water flows from through the pipe.

    Since the pipe goes down to the sewer under the ground and the water does not flow upwards, I then check the pipe from the other end that is through the roof. I am waiting for the rain coming because I do not know whether the rain will go into the pipe opening on the roof.

    I guess the rain probably goes into the pipe opening on the roof. So the leak happens on the loosing U connector. Though I can seal the U connector, I think why I can't add a cover to cove the pipe opening on the roof if that is the root cause? If no water flows down through the pipe opening on the roof, the leak will never happen even the U connector is loosing again. Is it correct or I misunderstand something? Again, I am learning.

  • renovator8
    12 years ago

    The water could be running along the outside of the PVC pipe from the roof flashing boot until it hits the elbow fitting.

    If you are sure the elbow fitting is leaking, cut it out and replace it. From the photo it appears that the elbow might not have been glued.

    It would be foolish to go out on the roof to install a cover when you could make the repair from inside for less cost, time and risk.

    Fix what's broken and stay off of roofs.

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  • brickeyee
    12 years ago

    "From the photo it appears that the elbow might not have been glued."

    Look very carefully at the elbow.
    At the very least it appears no purple primer was used, and possibly it is not even cemented.

    While PVC joints can be pretty tight without cement, they are NOT water tight for any length of time without cement.

    If you can pull the pipes out of the elbow it would mean they are not cemented.

  • klabio
    12 years ago

    coody,

    After reading your thread I am getting the impression you don't have a lot of Do It Yourself skills. That is not meant to put you down but in your case it might be a good idea to call a plumber and tell him you are getting water on your ceiling from a problem with your plumbing stack. It could be as easy as gluing the joint but it could be the boot.

    From the pictures you look to have a very steep roof. It will be very hard to get up there safely and if the flashing is leaking around the pipe your idea of capping the pipe won't stop the leak and it will cause smells in your house. The stack is there for a reason and a plumber will be able to stop your problem. It will cost you more than fixing it yourself but I don't believe that you have the experience to pull it off.

    The members on this board have put it in fairly simple terms but if you don't have the basics your best bet is to bring in a professional. Especially if you ever plan to sell that house.

  • renovator8
    12 years ago

    This project is rapidly turning into a candidate for the site linked below.

    Here is a link that might be useful: awards

  • compiler
    Original Author
    12 years ago

    There was thunderstorm last night. I did not see water flowed down through the pipe. So, the pipe opening on the roof is actually water proof. I still have no clue why the elbow ever leaked. Where did the water come from? I am not going to investigate it but will seal the loosing elbow joint and patch the back side of the ceiling board.
    I have pulled the pipe out of the elbow. See the picture. The back side of the ceiling board paper under the elbow joint has been black because of the leak. I am going to the Home Depot this weekend and buy the necessary material to repair the loosing elbow joint and patch the back side of the ceiling board. I hope the elbow joint will be leak proof but not permanently sealed in case I need to pull the pipe out of the joint without cut the pipe. The pipe right end goes to the roof and the left end goes down to share the washing machine drainpipe on the first floor. Could you experts tell me what material I should buy to tight the loosing elbow joint and patch the back side of the ceiling board? See the elbow joint and back side of the

    . Can you see what type of the ceiling board? The white stuff is insulation material covered on the back side of the ceiling board in the attic. Thank you for your help.

  • robin0919
    12 years ago

    The guys at HD should be able to tell you what you need to do. Take the pics with you.

  • sue36
    12 years ago

    If the look of the white pipe bothers you paint it the color of the roof. We did that and ours basically disappeared (ours is in the back, but a white pipe on a dark roof does stand out).

  • compiler
    Original Author
    12 years ago

    I am sorry I should say the right end of the pipe goes down to the first floor and the left end of the pipe goes to the roof.

  • bus_driver
    12 years ago

    All those pipe fittings should have been properly cemented and permanently joined at time of installation. Some plumbing codes require the protection of PVC from ultraviolet degrade. Painting with latex paint is an approved method. Paint (with latex) the exterior exposed pipe any color you choose.

  • renovator8
    12 years ago

    It would be silly to seal the pipe in the fitting with a temporary sealant. After the fitting has been properly sealed with primer and cement there should be no reason to ever disturb the pipe again.

    How you repair the gypsum board damage depends on the degree to which the board is damaged on the bottom side.

    Don't make simple problems complicated.

    Here is a link that might be useful: primer and cement for PVC pipe

  • renovator8
    12 years ago

    The drywall damage is beginning to look more like it was caused by mice rather than water.

  • brickeyee
    12 years ago

    "I still have no clue why the elbow ever leaked. Where did the water come from?"

    It leaked because it was NOT cemented.
    If it had been cemented you never could have gotten it apart, the pipe has to be cut apart.
    The water very likely may have come from rain or condensation inside the pipe.

    "I am not going to investigate it but will seal the loosing elbow joint and patch the back side of the ceiling board."

    You seal the pipe by correctly cementing the joint.
    Any hardware store should have the required primer and cement.
    Watch out, the purple primer permanently stains anything you drip it on.

    The back of the ceiling is the least of your worries, the show side is what needs to look nice.

  • compiler
    Original Author
    12 years ago

    I probably have found where the water came from. The leak happens when the first floor washing machine running. You are right. The pipe goes down to the first floor and shares the washing machine drainpipe and bath room pipes. The leak is due to the water evaporation and condensation passing through the inside pipe from the first floor. The rain does not go into the pipe on the roof. My question is why there should have a pipe on the roof to evaporate the water inside the pipe into the air? It seems unnecessary to evaporate the water inside the pipe into the air but just drain out all water into the sewer, right?

  • bus_driver
    12 years ago

    Explanations about the pipe through the roof have proved fruitless thus far. Will it resolve matters if we agree that the LAW says the pipe must go through the roof? Now the things remaining are to make the pipe itself leakproof by permanently cementing it with approved (by the LAW) materials and insure that rain is not entering around the EXTERIOR of the pipe.

  • renovator8
    12 years ago

    It is certainly possible that moisture laden air rising in the pipe condenses when it reaches the colder pipe in the attic and that the condensate water leaks out of the pipe as it runs downward past the loose joint. But that would only happen in the winter.

    Obviously, the rain does go into the pipe on the roof when it rains but just like condensate water it simply runs down into the sewer.

    As you should know from the repeated explanations on this forum, the pipe on the roof serves only to avoid siphoning of fixture traps and to vent sewer gasses to the open air and has nothing to do with evaporation. You are either not reading the explanations carefully or you are a leg puller.

    You should glue the pipe joint and move on.

  • brickeyee
    12 years ago

    :It seems unnecessary to evaporate the water inside the pipe into the air but just drain out all water into the sewer, right?"

    The pipe has nothing to do with evaporating water.

    It is designed to deal with sewer gas and trap siphoning.

    Try to actually read and understand the answers that you have been given.

  • aidan_m
    12 years ago

    Could you post a picture of yourself?

  • billkinca
    12 years ago

    "If the roof was not slope, I would really want to climb onto the roof and cover the pipe to see what would affect the house drainage."

    That might be a fun experiment to try, but you will want to invest in a mop and a gas mask first. No sense in not being prepared.

  • renovator8
    12 years ago

    Will his thread never die?

  • billkinca
    12 years ago

    "The drywall damage is beginning to look more like it was caused by mice rather than water."

    Might be cheaper to invest in a cat...

  • davidro1
    12 years ago


    1/.
    I understand that this thread died "naturally" earlier this year.

    I sense that a new generation of legpullers has been invented or created.
    This year I've seen a number of other similar patterns in other forums.

    So, beware! Professional exasperators have been released to the world. It's worse than Pandora's box. It might get so bad that one day it ends up killing all forum spirit.


    2/.
    Sewer gas is flammable, can be poisonous, and usually stinks.
    It can also be both odorless and lethal.

  • dgmarie
    12 years ago

    I do not think English is Coody's first language.

  • Jeannie B
    8 years ago

    We just had our house inspected and the inspector found the sewer vent too close to the window. How can this be remedied? What are our risks ? The vent comes from the laundry room....the window is that of the master bedroom. Also, should it be capped so leaves/debris/critters dint get in. Thanks!


  • renovator8
    8 years ago

    All of your questions were answered in the old thread you have for some reason reactivated.

  • Vith
    8 years ago
    last modified: 8 years ago

    Funny thread honestly. No one mentioned that the pipe should not terminate in the attic because of excess vapor from the pipe. (which is why they freeze over in very cold weather) Need to terminate to the exterior, and take freezing into account if you live in a cold climate.

  • renovator8
    8 years ago
    last modified: 8 years ago

    The vent in question did not terminate in the attic. The OP wanted to cap it inside. The problem was a leak associated with a normal vent which was shown in the photos 4 years ago.

  • Vith
    8 years ago

    I know, but he asked multiple times why it had to go to the roof and no one really answered that. The title of the thread asks that exact question. Some people could (in a round-a-bout thought process) get the idea to not penetrate the roof and terminate it in the attic because it would be easier and they wouldnt have to worry about the vent flashing going bad. Google searchers may come across this thread at some point and should know it has to go to the exterior.

  • renovator8
    8 years ago
    last modified: 8 years ago

    There was a leak in the vent pipe just under the roof. The photos showed a poorly designed and installed pipe with water damage to the adjacent framing and at least one joint appeared to not be glued (no purple primer). To solve the problem he wanted to cap the pipe in the attic. He didn't ask about leaving the pipe open in the attic so there was no reason to discuss it.

    The responses on the original Garden Web were meant to help other members with a problem rather than produce a searchable construction reference. The Houzz forum may be more ambitious.

    The practice of adding to a long old post is annoying. The member should start a new thread and reference the old one not that it would have been of any relevance in this case. The mew question was about how far a vent terminal had to be from a window.

  • Vith
    8 years ago
    last modified: 8 years ago

    Calm man, it was already bumped, I did not revive the zombie thread. Nor did I comment on the person that bumped it because I saw they made their own thread. I did read that the OP had a leak in the vent due to an improper connection and the problem was found out. However, I felt that a question that was asked multiple times was never answered.

    BTW, you dont control who reads these, they are fully accessible to anyone who comes across it.

  • renovator8
    8 years ago

    I was part of the original discussion and the question you raise was never asked nor was it relevant. Give it a rest.

  • Vith
    8 years ago

    Read the title of the thread. "Why does a pipe vent need to go out of roof?"

    Sigh..

  • renovator8
    8 years ago
    last modified: 8 years ago

    You didn't read the entire thread. The OP was questioning the need for a vent not where it should terminate.

    It is true that the vent could be terminated under the roof with an air admittance valve if that device is allowed in the OP's jurisdictions but I would never suggest that solution and the vent was already through the roof and would require patching the existing hole.

  • Jeannie B
    8 years ago
    Renovator8, can I contact you privately? I have a few questions and you seem so knowledgeable. I hate to keep bothering everyone on this site about the vent business. Thank u!
  • Ivan Martin
    8 years ago

    Question - I recently had a plumbing repair done, and as part of that repair had the vent stack pipe replaced. The top end of the pipe is open to the sky. There is a "screen" of sorts on it, but the spaces in the screen are large enough for a Hot Wheel car to pass through. Part of my old problem was that the pipe had become clogged with debris from a nearby tree that has very small leaves (a Locust tree). Is there some kind of cap I can put on the vent stack pipe that will still allow the air to flow in and out, but prevent the tree leaves, twigs and other debris from getting into the pipe and creating a new blockage? The vent stack pipe had previously had a cap of some kind, that had openings that were angled downward, but a roofer doing a roof repair a few years ago cut off the cap (and most of the pipe), leaving the uphill edge of the pipe about 1 inch above the surface of the roof. The new vent stack pipe now extends about 1 foot above the roof, but is still under the Locust tree, so will likely soon have very small leaves falling around it and into it.


  • bry911
    8 years ago
    last modified: 8 years ago

    Ivan - You can get a cap for it. Do a search for "vent stack cap" or "vent stack filter".

  • brandon_ruppe
    8 years ago

    So the apartment I moved into has a vent pipe that terminates in the attic. Unfortunately the heat system and air return are also in the attic. So when it started getting cold outside and I turned on the heat, my apartment began to smell like sewage. Quite an unpleasant surprise. Anyway, just wanted to thank Vith for confirming that the pipe does not belong in the attic seeing as he seemed to be the only person that took the question in the context that I took it.

  • arokitka
    8 years ago

    I saw a squirrel go down the pipe that stick out of my roof. Should I keep the squirrel?

  • Vith
    8 years ago
    last modified: 8 years ago

    Yes, they make a fine appetizer.

  • PRO
    Sombreuil
    8 years ago

    haha, I remember this thread.

    Casey

  • Chayce
    7 years ago

    So I'm interested in doing solar on my rooface. There are two vent pipes that prohibit having just one neat array of panels. Can I cut the vent pipe a little so the panels can sit above it a couple inches?

  • JDS
    7 years ago

    Not a good thread to drag up. Try posting an new one with a photo.

  • PRO
    Virgil Carter Fine Art
    7 years ago

    A 6-year old thread. But the answer remains the same. "Why does a pipe vent need to go out of roof?" So that it vents to the outside and not in the attic, with the ensuing problems of moisture, condensation, mold, fungus, and rot. Did I mention odors...?

  • JDS
    7 years ago
    last modified: 7 years ago

    Chayce's question is unrelated to the original thread and forces the unwary to read that ridiculous thread and possibly miss the new question. The question about the height of a vent above the roof under a solar panel should be in its own thread so this one can go away again.

    And include the slope of the roof, the height of the existing vent, the location and slope of the panels, the distance to any windows and the climate.

  • Susan Hadley
    2 years ago

    Bought my home 6 years ago...keep smelling dank odors coming up from the basement, discovered the drainage from the toilet to the septic was never vented through the floor/walls to the roof. There is a short 5-6inch stack just below the floor, leaving me with only 2 inches there. How to I vent this properly without having a pipe running through an upstairs room or hallway. Looks like no matter where we vent this to our roof, the pipe from the toilet to the septic isn't under any walls or closets to hide it. I wanted to be able to put a vent free propane heater down there if the furnace isn't working in emergencies, and I realized an open flame down there could be dangerous because of the gases coming from the septic and this pipe. How did this pass inspection?! How can I vent this damn pipe out horizontally, safely?


  • res2architect
    2 years ago
    last modified: 2 years ago

    This thread is 10 years old and not directly related to your question. Its best to start a new thread.

  • PRO
    Joseph Corlett, LLC
    2 years ago

    Dimensioned drawing please.

  • worthy
    2 years ago

    RES2 is right. But the answer is simple: Use an air admittance valve if it's legal in your jurisdiction.



  • HU-777285284
    last year

    It seems now a day vent pipe is not necesaary goes through the roof. the plumber just sealed it(without outlet). it only go downward into the drain system. is this way acceptable ?

  • PRO
    Joseph Corlett, LLC
    last year

    No. The laws of phyiscs have changed even less than the building code.

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