Redneck DWV

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Steve_P

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I have a 15 yr old ranch house with basement with a finished drywall ceiling and walls. The first floor sits on prefab 2x4 trusses and the plumbing, HVAC, electric runs thru in the truss area. I’m in TN and the county I live in did not have a building code or do any inspections until 2006. Yeah, I know this is crazy and it’s really burned me on various things. I had a minor plumbing leak (drips) in the master bath shower supply and when I tore out a portion of the basement ceiling to see what was going on I was shocked at what I saw when I started looking around. This led me to call the county to ask about building codes- none for this house, so what I saw now made more sense.

Bear with me for the description- it shouldn’t be hard to visualize. The house basically runs north to south for purposes of this mental image. On the first floor it has a master bath on the south east end and another full bath at about the middle of the house and also on the east side. There’s a third full bath in the basement with washer and dryer- it’s just north of the master bath and is on the west side of the house (so it's "between" the two first floor baths in the N to S direction). The house has two septic tanks- the basement bath goes to one and the first floor (basically) goes to the other. I know this because when it was being built I managed to see how the pipes were laid out before they poured the basement floor.

So, with the hole in the basement ceiling I started to snoop around and the entire house is wet vented thru the roof via the main 3” line that runs south to north- the septic tanks are north of the house. What’s even worse is that the basement bath is vented back into the main drain line for the first floor and connects in midway between the two first floor baths! It has a 3” PVC pipe that runs vertical up from the basement floor and then east to tie into the main drain line with a wye fitting (lying flat) that’s flipped to how it would normally be used if it was intended to direct flow.

Obviously this is all screwed up and is probably a record for doing things wrong. I can’t make it “right” but I would like to get rid of that wye which I know caused two drain clogs many yrs ago before we started being a bit more careful with flushes from the master bath. What I was thinking was to pull out that wye , replace it with a straight section, and instead vent the basement bath back upstream (south) of the toilet in the master bath.

Please resist the urge to tell me to rip out the entire house’s DWV system! I know it’s not right but we’ve really had no issues with clogs in ~10 yrs and the drains work fine.

The subdivision has another house just like it by the same builders and I’m sure it’s done the same!

The next time someone complains about codes they won’t feel so bad when they read this.

edit: the main drain line is 3" and not 4" as originally stated
 
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hj

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Y

Your description makes sense to you because you can see it while doing it. But we have difficulty, possibly because you tell us a lot more than we need to know. IF the "Y" you are referring to is the one where the lower bath's vent is being tied back into the stack, then it is likely NOT the cause of any stoppages, if it is causing any irregularities, and I do not know which direction it is facing, since it would depend on which way YOU are assuming the flow would be, but if it is "upward" then some water flowing down the pipe would be diverted into it and then it would become a drain instead of a vent for a few minutes, but again, that would not cause any problems.
 

FloridaOrange

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Your description makes sense to you because you can see it while doing it.

I would agree, I read the post several times last night trying to "build" the picture of the layout.

Steve,
Any way that you could put some sort of drawing together?
 

Steve_P

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Your description makes sense to you because you can see it while doing it. But we have difficulty, possibly because you tell us a lot more than we need to know. IF the "Y" you are referring to is the one where the lower bath's vent is being tied back into the stack, then it is likely NOT the cause of any stoppages, if it is causing any irregularities, and I do not know which direction it is facing, since it would depend on which way YOU are assuming the flow would be, but if it is "upward" then some water flowing down the pipe would be diverted into it and then it would become a drain instead of a vent for a few minutes, but again, that would not cause any problems.

Yeah, probably too much into but I figured too much was better to help you draw a picture.

The water flows south to north down the first floor's main drain line (I am 100% sure :)). Master bath is south of the Y and flows past it. the other
1st floor bath is north of the Y and doesn't flow past it. The Y that ties into the first floor main line at about midway down its length wet vents the downstairs bath. The Y is oriented so that water from the first floor drain line will mostly (all?) bypass the Y and not flow into the downstairs bath drain which is on the other septic tank.

The Y just seems like an invitation for a stoppage and I'm nearly positive that's where the two clogs were before because the master bath drain was NG (it is upstream of the Y) and the other first floor bathroom was fine and it is downstream of the Y. The clog was definitely not the toilet because it took quite a bit of snake to clear it.

Does that help any? I hope so :)

If not I can try and draw a pic but I don't know how to post it.

Thanks for the help
 

Steve_P

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DWV_01.jpg


Ok, that should do it. The layout in the master bath is pretty correct, the others two baths is a rough guess on how it ties in but that's what's there. The only vent is shown. All of the other drain lines less the mains are 1.5"
 
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Steve_P

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DWV_02.jpg


When I spoke of eliminating the Y fitting on the first floor DWV, this is what I had in mind. Would this be better? It seems like it would because it would both eliminate the Y and give the basement bath a direct shot at the vent stack. I assume they didn't do this because it was another $20 in PVC but I don't know.
 

hj

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Dwv

Right now you have a septic for the first floor, with an overflow to the septic for the basement, ANY TIME the line plugs up past the "Y". YES, it MUST be disconnected from the main line, but it MUST be tied to the vent riser at a point 42" above the floor on the first floor. As it is now, if the line to the first floor septic tank is plugged you would NEVER know it until the one to the basement tank also became plugged OR the tank filled up. Now, the "Y" connection COULD be the problem, under those circumstances, because at that point all the upstairs sewage would have to make a "U" turn to go to the downstairs system, which means a lot of solids could get caught there and eventually accumulate to finally stop the flow to the downstairs. At that point you WOULD know you have a problem.
 
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Steve_P

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Thanks HJ.

I never thought of what you said re the Y functioning as an "overflow" to the bsmt if there's a clog past it- but that's obviously the case.

Ok, so the verdict to be a little less redneck is tie the basement vent into the main stack at 42" above the first floor. I think this might be possible w/o too much trouble as the vent stack runs thru an interior wall in the closet- will have to look and see.

Does the bsmt vent line need to be 3" all the way until it ties into the main stack? I would assume so.

Also, where does the 42" come from? I'm sure it's a general code, but just curious on the logic (why not 36 or 48???) :) I understand you don't want a clog to force the flow down the other vent line like your example. But, if it was even a foot above the floor you'd still have nearly a foot of sewage in the tub as a warning :)
 

Nukeman

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The 42" comes from the fact that you need to connect in at least 6" above the flood rim of the highest fixture served by that vent. This would normally be a lav installed at 36" height (36 + 6 = 42").
 

Steve_P

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thanks. I realized that a few minutes later and was going to edit my post but you beat me to it!
 
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