House has no vent system at all, trying to add one

[rorythom]

Hello,
My husband and I bought an old house last year. We have a very small budget with which we have been repairing it. Along the way we have discovered that there is no venting system at all for the plumbing. This was a foreclosed home that I purchased through auction direct from bank/gov so the inspection process was a little different. I never actually used the old toilet because it was taped shut with a sign that said it "appeared to be malfunctioning". Apparently from what I have heard from neighbors, the previous owners had problems with back-ups in the system (which makes perfect sense seeing that there are no vents.)

We are moving the kitchen onto the back of the bathroom wall, so all plumbing will be located on one wall on one floor. There is a basement below where the main 3" drain runs horizontally to an outside 4" main sewer pipe that goes vertically into the ground. From diagrams that I have seen, I would think that this main drain might have a vent above it, however it does not.

I am attaching a diagram of the existing plumbing and a floor plan of how things will be laid out. I am trying to figure out the best place to put in a vent to serve the fixtures that we have. I was hoping because they are all on one wall that it would make solving the problem easier, however the wall is old and thin and isn't even the width of a 2x4. I am thinking of furring out the wall or perhaps just running the vent pipe on the outside of the wall and boxing that part of the wall out.

But I cannot figure out what size vent pipe to use and where to put it in the line. I would like to add on beyond the toilet and put the vent pipe straight up behind the kitchen sink, but I have read that the toilet should be add the end of the drain. The toilet sits directly above the 3" horizontal drain and is connected by a sanitary tee. Originally it had a cleanout at the end of the line, but that's now where I would like to plumb in the kitchen sink and add a vertical vent up through the roof. Would that work? Could the tub and toilet wet vent through that? I could vent the washer and bathroom lav up and tie-in to the proposed main vent in the attic.

Perhaps I am over my head here. What is really throwing me is the placement of drains into the line, particularily which order they should be in. There are some other branches off the main 3" line that you will see in the diagram that I am trying to figure out how to utilize. I don't think the 1 1/2" line is viable anymore. We had to fix the slope of the 3" pipe (it was not properly supported and was actually sloping away from the sewer), so now the 1 1/2" is up between the joists. Besides it is coming straight out the top, which seems to be frowned upon.

Any thoughts would be very welcome. I'm going round and round inside my head trying to work it all out. Thanks! ps. We are in California

[Gary Swart]

Every fixture needs a vent. That does not mean all of them have to go through the roof, they can be joined. It really seems to me you are into something that is beyond a DIY job. I realize you are on a very limited budget, but you really need professional on site help on this one.

[hj]

Every fixture needs a vent, but that does not mean every fixture needs its own vent. They can be combined and/or shared when possible. A toilet, and most plumbing, does NOT need a vent to drain. In fact a vent is usually installed to "limit" how well it drains. If the toilet did not, or does not, flush properly, you have some problem other than a missing vent, usually an obstructed drain line.

[rorythom]

Every fixture needs a vent, but that does not mean every fixture needs its own vent. They can be combined and/or shared when possible. A toilet, and most plumbing, does NOT need a vent to drain. In fact a vent is usually installed to "limit" how well it drains. If the toilet did not, or does not, flush properly, you have some problem other than a missing vent, usually an obstructed drain line.

The main horizontal drain was sloping away from the vertical sewer stack quite significantly, maybe caused an issue. We looked down the pipe as far as we could with a flashlight and it was surprisingly clean and open. Of course that doesn't tell us about the rest of the line, but it is a 4" pipe. Seems pretty hard to clog that up, but maybe!

Yes, I do think we need professional assistance. I'm looking in to that. In the meantime, I keep thinking about it, because once I start a puzzle, I always want to solve it!

[leejosepho]

A toilet, and most plumbing, does NOT need a vent to drain... If the toilet did not, or does not, flush properly, you have some problem other than a missing vent, usually an obstructed drain line.

In my own case, that turned out to be a poorly-made toilet that could not flush well even while sitting on blocks in my driveway to test it after the vent I had installed had made no difference at all.

...once I start a puzzle, I always want to solve it!

Since you are moving the kitchen and all plumbing will eventually be consolidated, I would likely make that thin (shared) wall into a thick one and run a 3" vent for everything up through there somewhere.

[rorythom]

Since you are moving the kitchen and all plumbing will eventually be consolidated, I would likely make that thin (shared) wall into a thick one and run a 3" vent for everything up through there somewhere.

I agree, that was my thought too. One problem we set up for ourselves was finishing the whole bathroom, including drywall, paint and tile before discovering the lack of venting. So now we are looking at adding to the wall instead of replacing it entirely. Thinking of putting up a new wall on the exposed kitchen side for the pipes to run through. This has been a HUGE learning experience as far which order to do things in. We were too eager to see a whole room finished (ie: the bathroom, oops.)

[rorythom]

The one aspect that I am really hung up on is whether the toilet should be at the end of the line. In the plumbing code it states that "The water closet fixture drain or trap arm connection to the wet vent shall be downstream of any fixture drain or trap arm connections." This statement leads me to believe that the lavatory and tub should be upstream from the toilet and that it should NOT be at the end of the line. Can someone clarify for me? Thank you.

[hj]

quote; One problem we set up for ourselves was finishing the whole bathroom, including drywall, paint and tile before discovering the lack of venting.

At that stage, before the drywall, any "lack of venting" should have been obvious. "Lack of venting" is NOT obvious after the walls are sealed, because other problems can mimic a lack of vent.

[rorythom]

quote; One problem we set up for ourselves was finishing the whole bathroom, including drywall, paint and tile before discovering the lack of venting.

At that stage, before the drywall, any "lack of venting" should have been obvious. "Lack of venting" is NOT obvious after the walls are sealed, because other problems can mimic a lack of vent.

We still have the other side of the wall open in the kitchen. So while your comment is valid, it doesn't apply to this situation. We didn't notice the lack of venting because we just plain didn't address the plumbing beforehand, which obviously having gained some experience, we would have done sooner. Hindsight. But I can tell you with 100% certainty as I stand in the basement looking at the sum total of the plumbing system that there in no vent whatsoever and the only thing protruding through the roof is a wood stove chimney.

One thing I have noticed on these forums, and I don't blame you because there are a lot of beginners in over their heads- like us-, is a willingness to criticize but not necessarily help and answer questions being directly asked. I am trying to learn. I am trying to understand. Because I am truly interested in understanding how things work. I wish the minute that you took to reply had been an answer to my question about the placement of the toilet in the wet vent group.

[leejosepho]

The one aspect that I am really hung up on is whether the toilet should be at the end of the line. In the plumbing code it states that "The water closet fixture drain or trap arm connection to the wet vent shall be downstream of any fixture drain or trap arm connections." This statement leads me to believe that the lavatory and tub should be upstream from the toilet and that it should NOT be at the end of the line. Can someone clarify for me? Thank you.

I believe that means your toilet and tub are in the wrong order since the discharge of the toilet should not flow past the discharge of any other fixture since that could (at least in theory) draw the downstream trap dry. So if or when you might re-do some things and add a vent, just be sure the toilet has the lowest connection at the stack.

[rorythom]

I believe that means your toilet and tub are in the wrong order since the discharge of the toilet should not flow past the discharge of any other fixture since that could (at least in theory) draw the downstream trap dry. So if or when you might re-do some things and add a vent, just be sure the toilet has the lowest connection at the stack.

Thanks! You're right, they used to be in the incorrect order, but technically they are not in any order yet. When we put in the new tub, we disconnected the line and have yet to hook it back up (I didn't know whether to connect downstream or upstream from the toilet.) But what you say makes sense and matches what the code says to my interpretation: connect the tub upstream from the toilet, as well as the lavatory which would be vented to serve the bathroom group. I would cap the old 1 1/2" line that used to go to the tub and use the other 2" pipes (downstream from toilet) to drain the kitchen sink and washer, both having their own vents (so no worry about their traps being drawn dry by discharge of the bathroom group.)

[jadnashua]

If each fixture is properly vented, it really doesn't matter. A bathroom group is allowed to 'wet vent' bits, then the order really matters (in a wet vented bathroom group, the only group that can be wet vented - you don't need to vent each thing if it is installed properly).

[hj]

Since the back side of the plumbing wall is open, how about a picture of the piping. A poorly designed system COULD be vented without a pipe through the roof. Telling someone how to fix a faucet is a lot different than trying to tell them how to install a complete plumbing system. The toilet can be ANYWHERE you want it to be if the venting is done properly. IF it is NOT done properly, then the order is also immaterial because it will probably not work the way it should anyway. Normally, you CANNOT stand in the basement and see any venting, good or bad.

[rorythom]

Since the back side of the plumbing wall is open, how about a picture of the piping. A poorly designed system COULD be vented without a pipe through the roof. Telling someone how to fix a faucet is a lot different than trying to tell them how to install a complete plumbing system. The toilet can be ANYWHERE you want it to be if the venting is done properly. IF it is NOT done properly, then the order is also immaterial because it will probably not work the way it should anyway. Normally, you CANNOT stand in the basement and see any venting, good or bad.

This is a very simple house with a very simple set-up but it's certainly not the norm. We severed all drains when we took out the old bathroom fixtures and there were no vents attached (perhaps that's why I didn't realize that they needed to be there.) The previous owners, it seems, attempted to vent the kitchen sink out the exterior wall with a small stubby pipe that extended maybe a foot above the drain level. Maybe it was somehow miraculously venting the entire system, but I doubt it as it was at the end of a long 30' run of 2" pipe that didn't directly connect to the horizontal 3" drain (see drawing.) It is immaterial now because we are moving that kitchen sink to the back side of the bathroom where there is no venting to tie in to. So as it is now, the system has no venting.

The thin wall has no drains of any kind thus far, so a photo would show nothing. I could take photos underneath and that might be helpful. The only thing attached is the toilet (which sits directly above the 3" horizontal drain) and I have been trying to determine (by reading forums and plumbing code) which fixtures to add on upstream from the toilet with new connections and which to connect downstream from the toilet to the existing 2" branches so that the toilet will be in the correct order relative to the venting, since there is mention of the order being relevant in the plumbing code. It seems the rest of the vented bathroom group should be upstream from the toilet and the kitchen sink downstream on a 2" branch with its own vent, then tie them together into one vent at attic level. I want to have only one vent going through the roof.

It seems to be a chicken and egg situation. I cannot determine where to run the vents until I decide which side of the toilet to put the drains on but you insist the order does not matter if it is properly vented. Riddle!

[MichaelBukay]

are you pulling permits for this job?