2nd Floor Bath & Laundry

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NC remodels

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North Carolina
Hey all,
On to the 2nd floor plumbing. Attached is the plan and isometric. The laundry and bath share the plumbing wall. Please let me know what you think. Also a few questions..

-I may not do the floor drain for the washer and just add a washer tray with a 1" drain line to the exterior (no trap and no invasive work to the 100 year old hardwood floor). Is this fine for any potential flood problems with the 2nd floor washer or would you advise the floor drain? If so, what size? The washer pan would be the simplest and least invasive. I also plan to add an emergency cut off at the supplies.

-Is this 3" waste enough for the bath and laundry? It is only for the 2nd floor. It will tie into the 4" that drains the first floor bathrooms. I'm guessing its only about 12 DFU's total so I think I'm fine

-The 3" through the roof vent is venting everything here plus the downstairs bath and 1/2 bath. This is about 25 total DFU's so I think I'm ok

-I plan on putting the cast iron back for the main stack to help reduce noise. I may even do the Quiet House idea https://www.charlottepipe.com/quiet_house.aspx. It uses CI of all drains and PVC for vents

-My hybrid DWV plan is to use CI for all drains that I don't want to hear noise, solid core PVC for all drains that are more isolated and foam core PVC for all venting. I ran this by inspections and they were OK.

Thanks again!!


In the Trades
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Berkeley, CA
Some comments, then on to your questions:

- Assuming all trap arm length limits are complied with, looks OK to me as is.

- NC has amended the IPC wet venting rules to provide more flexibility, they are not limited to bathroom groups. So you could use the laundry sink/standpipe wall to wet vent the floor drain. Likewise you could arrange things to have only one vent takeoff in that wall.


- The WC doesn't have to be the last fixture on a horizontal wet vent under the IPC. So you could send the bath drain to the 3" line directly, and join the lav to the 3" line closer to the WC, if desired.

- Some of the 2" pipes could be made 1-1/2", I can elaborate if that interests you.

Your questions, in order (numbering can make responding easier):

- I'm curious what others think. I might be inclined to do a 1-1/2" drain out the sidewall if I could include some sort of damper to block the air flow. [There are mechanical trap replacements that could be used for this.] The only second floor laundry room I did, I have no floor drain, but I have washing machine supplies default off, and you need to start a timer to turn them on for a limited time period.

- Yes

- See table 906.1 and/or table 906.2. If I'm reading it correctly, 906.1 says a 3" vent on a 4" stack can handle 43 DFUs and be up to 250' long.


- On the last house (of two ever) I plumbed, I used a mixture of plastic and cast iron. All the plumbing in the crawl space was plastic, as was the plumbing directly behind each sink and immediately at each tub; I switched over to cast iron for any other drains above the first story floor elevation.

Cheers, Wayne
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