Plumbing bathrooms and kitchen, UPC

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Following are some pictures of how I plan to plumb two bathrooms and a kitchen sink. Any advice will be appreciated.

Here is a picture of the bathroom drains and vents with the framing. Cinder block foundation not shown. Vents green, drains red. As you can see, the house was not framed with plumbing in mind. One of the things I am wondering about are the vent offsets. I am in a UPC area. Is it OK to offset vents at less than 6 inches above fixture flood rims if the offsets are at least 45 degrees?


Here is a close up of the underfloor plumbing for the bathrooms. I plan to hang the under-house drains under the floor joists, in a crawl space that is about 2 1/2 feet high. Would it be a good idea to take the left cleanout outside the house?

The vent for the downstairs toilet is at less than a 45 degree angle (hence the 60 degree Ell). I don't see a simple way to avoid that. Is this acceptable when it cannot be avoided? That vent runs up next to a closet on the second floor - does it make sense to put a cleanout up there with an access panel in the closet in case the low angle causes problems?


Here is a closer view of the underfloor fittings for the toilets. The question mark is on the vent that that is less than 45 degrees.

To the back and on the right is the kitchen sink's drain dumping into the main drain. I show a Wye on the main drain, with a street 45 and a 22 1/2 degree fitting on the kitchen sink's drain, is that acceptable?


Here is a shot of the upstairs bathroom plumbing. The offset with the question mark is one of the ones I am wondering about. I could raise this offset, but that would put the glue joint for the inverted san tee right in a stud. Seems a bad glue joint would be more likely if I move the offset up than a clogged vent if I don't.


Below is the plumbing for the kitchen sink. Can I run the drain at a 45 as shown? The air admittance valve is needed as there are windows above the roof where the vent would come up (the kitchen is one story), is there a reason this wouldn't work? I show the AAV in the wall, but I know it needs to be accessible.


Thank you all for the great forum! Please let fly if you see something wrong.



The Plumbing Wizard
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Bothell, Washington
It's okay on the kitchen to go sidewise under the window and then go up. Just use waste fitting below the flood level.
Much better then an AAV.
An AAV needs to have constant air to it, and be accessible.

The drawing looks nice.
I like to use more 45's in my layouts, but what you have will work too.

California may let you wet vent the upstairs lav over the upstairs toilet too.
And wet vent the downstairs lav over the downstairs shower vent.

But the way you have it drawn will pass inspection anywhere.
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Master Plumber
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Cave Creek, Arizona
Cleanouts in the crawl space are almost useless. If you do not have one in the wall, then I will use the fixture connection to unplug the drain. I DO NOT go into crawl spaces to snake drains.
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