Help on wastewater piping design??

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Old 08-10-16, 09:19 PM
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Help on wastewater piping design??

Wondering if anyone can help me on the rough in of a plumbing system. I keep reading and reading but its hard to find the answers that I need...

First off the structure is a single story 1000sqft home, that will have the bathroom(toilet, sink, tube), laundry hookup and kitchen sink.

The sewer main comes from the street and is 4in pipe, it takes a turn behind the home and then a turn into the crawl space. It was never designed correctly as the system was never vented but the stack will come up right at the head of the tub.

I want to extend a 4in pipe under the wall that the toilet, sink and tub will be installed on and tee all the drains into the 4in pipe. I then want to run a 2in pipe to the future laundry room. I was also going to tee 2in off the stack to run to the future kitchen sink.

Here is a rough sketch..

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Layout of fixtures..

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I am thinking I am over designing the system in my head, wanting to install vents/aav, over sizing pipes and clean outs...

Also we have no codes in this area, very rural and no need for permits...

If anyone can help, toss out some pointers, etc...Would be fantastic!
 
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Old 08-10-16, 09:55 PM
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Three things in your post jump out at me. In reverse order:
Also we have no codes in this area, very rural and no need for permits.
Are you SURE about not needing any permits? Your city/town/village may not have any requirements but the county may. Often it will be the county Health Department that oversees drainage permits. Even if the county has no requirements there may indeed be State requirements that must be met. Sadly, it is incumbent upon the builder (you) to make certain there are no governmental requirements to be met. Failure to follow the rules/laws could mean fines and also tearing out what you have added.

I was also going to tee 2in off the stack to run to the future kitchen sink.
You cannot do that. That connection would constitute a "wet" vent. Also, you need to use a wye connector, not a tee. By using a wye and properly venting at the sink it is acceptable.

I am thinking I am over designing the system in my head, wanting to install vents/aav, over sizing pipes and clean outs.
Do not use AAVs if you can run a proper gravity vent. Do NOT oversize any drainage piping as doing so is an invitation to clogging. When you increase the inside diameter of the drain you lessen how high the water will rise inside the pipe. This leads to crap and corruption "growing" on the walls of the pipe because there is seldom, or never, enough water flow to scour the pipe sidewalls.
 
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Old 08-10-16, 11:07 PM
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This area is very strange, I am from Cali originally and I am use to needing a permit for EVERYTHING including painting your house. Here I go into city hall and they just look at me funny.

The city is responsible for electric and they give a squat about what is up to code, it is very scary! The house I am working, was actually wired to the main supply to the original fuse box on the church and ROMEX wiring connecting the two buildings together.

Plumbing is another odd one, the church had new plumbing done in say 2000 and it is a joke! The main is oh 8ft down, the toilets/sinks are in the basement which is 7ft! I was wondering why the in floor drain wouldn't work and the toilets wouldn't flush...Turns out there is a buried weeping system somewhere tied into a back flow preventor and the line gets overwhelmed and closes....thus causing things to not work...

You don't know how many times, I look at these structures and WISH they need permits for work from someone...Maybe just once a license contractor would have been used and permits pulled...

Ah your right, that would be a wet vent.

The issues with running proper venting, is the walls are supporting and the few that aren't all have double 2x8's under the walls thus it is near impossible to stuff plumbing into the walls. Here is a photo, looking into the crawl space, showing where they knocked threw to install a bathroom in the 60's...Don't mind the pitch pipe...another nightmare!

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Thanks for the terminology clear up! I have installed many irrigation systems but this is my first plumbing experience so I get parts confused.

Do you think, that if(room permitting) I install a Wye connector going from the 4in stack to a horizontal 4in pipe and ran the proper Wye connectors off that to the toilet, bathroom sink, kitchen sink, laundry and tub with the proper venting. I am thinking vent at the laundry, kitchen sink and bathroom sink..Of course the main stack will also be vented..That would work?

I do have the chart, with the correct pipe sizes per fixture somewhere...
 
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Old 08-11-16, 11:16 AM
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I'd lay it out with a 3" main. Wye off for the tub (1.5"), toilet (3"), and sink (1.5"). Also for the kitchen sink (2") and further up for the laundry (2"). At the end of the 3" pipe, add a cleanout.

The tub and toilet don't need their own vent. They will use the main stack as their vent (since it's only a 1-floor house).

You'll need a vent up to the attic for the bathroom sink, kitchen sink, and laundry. If you have enough room in the attic, it's best to connect them all together (back vent) and go up through the roof with a single 2" pipe. Fewer holes in the roof.

Hope the brief description helps!
 
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Old 08-11-16, 12:32 PM
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Thanks! Yes that description helps!

My "rough" sketch up for the shopping list...

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With everything I am doing this project in a phase, right now I want to get the main stack completed and then later on add the branches to the bathroom sink, laundry, and tub. Toilet and kitchen sink are the mandatory at the moment...The gift of a hotwater heater will bless me with a shower/tub lol

Whats your thoughts on running the stack into the crawl space? Should I elbow off the outside line into the crawl space, elbow up and add in a wye for the vent/stack? Or should I just angle the stack from the outside elbow and then just tee for the vent? Here is a sketch for a visual...

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Old 08-15-16, 11:14 AM
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I like your plan. Once you're in the crawlspace, you might as well do most of the work, then just cap off whatever you're not using temporarily using rubber fernco caps. Open then up and continue when you're ready. Though it's always easier to do the main part of the plumbing before you start using it. The pipe will be ... umm... cleaner

For the vertical view, I like your second option better. Fewer elbows mean fewer places for things to get stuffed up. But either are code-compliant. But use a wye in either case. You can't use a tee on it's back like that.

(code-wise, you might be able to since it's just a vent - but I've always learned never to use a tee on it's back, so safer to use a combo wye for the main vent).

Also, don't forget about venting your 2 sinks and washer!
 
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Old 08-15-16, 11:44 AM
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Sweet!

I hear you about getting the main part setup, I had thought about that...I was like okay how can I get this done in two parts but not have to deal with the nasty part of sewer....

Think your right on the wye! I think if I use that, the angle of the pipe will make the vent vertical and not at an odd angle.

Won't forget the venting! I will have this to come back to for reference.

Now I just need to dig up, far enough to find a good section the the orangeburg piping to splice into. I am praying that it will hold up for a few more years, before I have to hire a back hoe operator to dig down 18ft! Though I also hope the line is connected to the sewer main, my neighbor told me her sewer line just runs out to a ditch in her neighbors back yard....
 
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