DWV

CD

"I have a cape style home where the bathroom and two bedrooms are on the main floor. I have one bedroom on the second floor and no bathrooms. I would like to install a bathroom directly above the bathroom on the main floor and wondered if I could tie the new lines to the existing lines without touching the existing vents or drainage for the bathroom on the main floor. I had two plumber look at the job and they came up with two different solutions. One claims that I need a new stack line and the other claims that he can cut into the existing stack, venting the new fixtures above the existing fixtures as if they were not there. Space in this house is very limited and getting a new stack will be hard.
Which one of these plumbers in correct according to code?

chuck shaw

Codes vary from state to state

However I can not believe that anyone would allow you to just add to the stack. Having said that, there is also the the horizontal branch off a vertical stack approach, that is seperatly vented. The first floor would have to be the horizontal branch, with a seperate vent run 6 inches above the flood level rim, of the highest fixture on the second floor. More than likley, this would mean, replumbing the whole first floor as well. Having said that,I would opt for the plumber who is recomending a full stack be run into the basement. If I was looking at the job, that is the way I would do it.

Chuck Shaw

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HeavyP

Bathroom

By my local code, you can not tie the waste from the new bathroom into the existing stack vent from the first floor bathroom. Where the stack comes up past the second floor is the vent for the existing bathroom. It would probably "work" but is not code. The plumber that told you you need a new stack is correct. Chris

bigugh_4

2nd story fixtures

can and will present positive pressure problems to the traps of the first floor fixtures, if they are connected to the system incorrectly. I have seen trap contents placed on the cieling of bathrooms. (not nice). your plumber should understand this and also the inspector. good luck!
bigugh

HeavyP

I have seen that too!...(nm)

.

Mad Dog

The legit guy is right

run a new stack Mad Dog

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ScottMP

new stack

Scott

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chuck shaw

a drawing

I dont know if this will help or confuse the issue. I have attached a drawing, not having seen your plumbing system, these drawings are represenitive of typical plumbing systems. The one in the upper left, is a single bathroom. The one in the upper right is one method that was proposed to you, which is incorrect. The two on the bottom are both correct, according to my local codes. The one on the bottom right is the other option that was proposed to you. I added a "jumper" to show that pipes were not attached, it is not a running trap. Also, to keep the drawing simple, I did not add the necessary clean outs, or put sizing on the pipes.

Chuck

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Mike T., Swampeast MO

If you can run the existing vent lines from the sink/tub/etc. ABOVE the level of connection of the HIGHEST drain you should be fine by [most] codes. (as shown in low-left drawing).

If everything on the 1st-floor bath is wet vented already it gets really "grey."

To the best of my knowledge stacked toilets are always allowed on a soil stack without individual venting for each as long as they are within some VERY short distance of the stack (18" I think but am too lazy to get out NPC book).

The KEY is getting the re-vents ABOVE the highest drain connection to the soil stack (where it becomes the stack vent). I believe you can tie the 2nd floor vents into the re-vent from the 1st floor as well if it "works out" better that way.

Jackchips

Drawings

sure add to the topic, Chuck. Nice job.

As an inspector, I agree with your evaluation.

CD

The drawings...

depicted the problem and a solution perfectly. Thank you very much for all your help.

CD