new bathrooom rough in questions

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Old 12-20-18, 05:50 AM
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new bathrooom rough in questions

Currently, I am working on roughing in the plumbing for a renovation / new bathroom. So far, some of the rough plumbing has been started, however, there are a few questions that I have in order to finish the rough-in.

There has been a new 2" sewer stack added specifically for this room. The toilet is within 4' of the new stack. The main drain, which will tie into existing is 3".

1. The stand-up shower drain is a 2". This drain will dump into the 3" main drain within 1' of the new vent stack. Does the shower drain need a branch vent?

2. The new sink/vanity will be located on the opposite wall of the new main drain run. The drain run for the sink will be roughly 6'-7' from the sewer stack. Does the sink need a branch vent?

3. The room where the bathroom is being added is a single story addition to a 1 1/2 story house. One thing I noticed is that the new stack vent comes out of the roof near a window. The stack is not directly in front of the window, but plumbing code reads that if a vent is located within 10' horizontally of a window that it could be an issue. In my case, the vent is off to the side of the window. Could this be a possible issue?

4. There has been some debate regarding the choice of a pedestal sink or vanity for this install. However, in this case (due to the foundation), the plumbing for the sink has to come up through the floor. Does anyone know of a way to install a pedestal sink with plumbing coming up through the floor? Upon researching this topic, S traps were suggested, but I have also read that they are illegal. Thoughts on this?

Advice and insight are greatly appreciated.

Thanks.
 
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Old 12-20-18, 11:31 AM
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Here is the drainage layout for clarity.

 
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Old 12-29-18, 05:50 PM
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All looks reasonable. I assume the 2" stack is actually a 3" drain, with a 2" vent, right?

Whether you use a pedestal or vanity, it should be a p-trap. S traps are no longer allowed. Is there a reason you can't come up through the wall, tee-out to the sink, and continue up through the wall to vent it?

If there's no way to vent, you may be able to use an AAV in a vanity, though many towns disallow AAVs.
 
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Old 12-31-18, 08:59 AM
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Thanks for the info. You are correct in the assumption that there is a 3" drain with a 2" vent. I did go ahead, and tee off of the sink location, and tied back to the main vent stack. Since the drain had to come up through the floor, I just did a 45 to get the pipe back into the wall, so that I could put the vent in.

As for the outside stack, are there any minimum requirements? I put a 2" out the roof, that should be sufficient, correct?
 
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Old 12-31-18, 02:04 PM
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Most areas are fine with a 2" vent through the roof (with appropriate boot, roof sealing, etc).

Some areas with high snowfall require the vent to be increased to 3" through the roof to reduce the probability of freezing inside the pipe. I don't know if SD would fall into that requirement or not.
 
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Old 12-31-18, 02:40 PM
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Thanks for the info. I will have to look into the plumbing code to double check. I spoke with one local plumber, who only suggested a 3" through the roof would be better to keep the pipe from freezing up.

However, he never made any mention of it being a code requirement to have a 3" through the roof. He simply said that the 2" was fine, but 3" would be better.

In the event, that I did decide to change to a 3" stack out the roof, does that 2" to 3" adapter have to be inside the building, or can it be at the roof?

Where the pipe goes out through the roof is rather limited on clearance.
 
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Old 01-01-19, 06:45 AM
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In the event, that I did decide to change to a 3" stack out the roof, does that 2" to 3" adapter have to be inside the building, or can it be at the roof?
It does need to be inside the house (attic) to be effective. The most likely place for the pipe to freeze up is at the roofline. I've never seen a vent increased after it
 
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