I am moving a vanity and installing a double vanity. I have access from the basement, so can I come straight up into the vanity with the drain and water supply or should I still come up inside the wall. Either way can be done. If I come up inside the wall is there a rough in height(34 1/2" cabinets)from the floor. Thanks shulta44

Sorry should had asked both questions at the same time. I am also moving the toilet over. How much room should I leave on the side between the 3" pipe and the floor joist. I am trying to keep it centered as much as possible so the closer to the joist the better. I would cut out the joist and install a double header but unfortunetly that is not a option.
Thanks
Shulta44

Whichever is easiest, and the height isn't a concern. Low enough to not get in the way of the drain and trap and high enough to put valves on, about 6-8" above the floor of the cabinet. The drain will tie into the stack a few inches below the sink bottom. You can put it on the stack first and adjust the drain pipe under the sink but you should still measure and maybe do a mock setting.
The vent needs to rise above the trap connection and the (I assume) angle up and over to the existing stack, and that has to be the number of feet straight up and then away that is required by your local code, but in the average bathroom it's probably OK.

I'm nost sure what you mean by wanting to center it but also keep it as close to a joist as possible? Why does it have to be close to a joist?

I hate to bust Joys chops but it is important. If you come up through the floor you will be building a illegal "S" trap. To stay legal come up it the wall with 2" and install a 2X1 1/2" sanitary tee 18" to center off the floor for a 1 1/2" stubout. From the top of the tee run up to the attic where you may revent back to a existing roof vent. You may come off the stubout one of two ways.
1. With a wye and connect a trap for each basis, **OR**
2. Connect the basins with a continuous waste an d connect back to a single trap. Good luck, Tom

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I am also moving the toilet over. How much room should I leave on the side between the 3" pipe and the floor joist. I am trying to keep it centered as much as possible so the closer to the joist the better. I would cut out the joist and install a double header but unfortunetly that is not a option.

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I'm not sure I understand your question. Are you crossing a joist? Running with a joist? What's your concern? Is there a Joist that you have to cut? What? Back to you, Tom

Tom how is through the floor making an S trap? I just put my kitchen drain through the floor because its' on an outside wall.

Hi Joypulv...

I think Tom was thinking you were suggesting not venting the drain, but in reading your post, I can see that you did suggest the vent and that would NOT make an STRAP... ;)

However, you did say that height didn't matter.. when in fact there is a STANDARD ROUGH IN for sinks which is 18" to center of drain off the finish floor. I'm pretty sure the Shulta would want those numbers... wouldn't you if you asked the question?

You can also install a drain pipe in an outside wall... no issues here whatsoever. Here, you can't install a PTRAP (holds water), but you can run drain pipes in outside walls even in the very coldest climates, so there is usually no reason to come up inside the cabinet.

Anyway, you do seem to have some good general knowledge about things, but I got to tell you I really don't understand why you even answer these questions when you know there are like 5-6 plumbing experts on the page that answer questions religiously every day? *shrugs*

I know you are just trying to be helpful, but you almost never provide quite enough information and we just end up coming in here and reposting everything you did PLUS all the other needed info... and YES, sometimes we even need to correct you.

I'm sure you won't like this, but in my opinion, you really should leave plumbing questions to the real experts... ;)

Just my opinion!

Mark

OK, I defer to the experts.

OK Mark, Here's my rebutta.
The OP said;

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I have access from the basement, so can I come straight up into the vanity with the drain

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Connecting direct to the basement spells "S" trap to me. No mention of a vent here and Joy replied;

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Whichever is easiest, and the height isn't a concern

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Both wrong answers. I then advised the OP to come up in the wall, stub out and continue on up with a vent. So you don't think the OP was building a "S" trap? Please tell me where I went wrong. Until then I stick with my original post. Regards, Tom

And now I see where I was wrong (so I guess my kitchen isn't code, or at least I'm not sure, since the vent always was 4' off to one side, and in fact goes up the chimney shared by the FIREPLACE, and I know that's not allowed either, even though this all passed inspection in 1967).

The local interpretation of a P trap considers a horizontal run after the trap and before going back down. In my log home, in wall plumbing is not possible. They do not allow any S trap but did allow me to use 2" PVC and install a 4" horizontal run after the P trap before going back down through the floor. In reality, this is no different than piping from a p trap into a wall connection that then goes down the wall.

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he vent always was 4' off to one side, and in fact goes up the chimney shared by the FIREPLACE,

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Hey Joy, You have a fireplace in your kitchen that the kitchen sink vent runs out the roof through the chimney?
And it passed inspection? What a novel way to vent a fixture. I don't want hurt feelings over this but our answers have to be "bang on" and yours wasn't. WE can't allow confliction answers,
If you will go back on the experts answers you'll find that we all pretty much agree. And if we disagree we always give a reason and explanation. Nothing personal here. Hugs?


Hi Ma0641,

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The local interpretation of a P trap considers a horizontal run after the trap and before going back down.

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You have just described a "S" rap. You were OK until you said:

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After the trap and before going back down through the floor.

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Excuse me but doesn't a "P" require a vent?

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In reality, this is no different than piping from a p trap into a wall connection that then goes down the wall.

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Say What? I keep looking for the word "vent" in your post but haven't found it yet.

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They do not allow any S trap but did allow me to use 2" PVC and install a 4" horizontal run after the P trap before going back down through the floor.

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Once more you've described a trap without a vent. That's a "S" trap in my code book.
What country do you live in? Or if you live in the States what Plumbing Code do you fall under? I'm not trying to heavy up on you. Simply attempting to understand you a little better. Peace, Tom

I'm in a custom house built in 1967 and a lot isn't code. I don't know if it was then or not.
I have a friend who was a builder in VT his whole life and he has done a lot of work here and I haven't pulled a permit.
My first house was a 1918 two family and I filled it with butylene in the 80s. I wonder what the present owners have done with that.
I'm just a DIYer and will stop answering these questions!
I think I'm being misinterpreted partially anyway.

Sorry guys should had provided more info. Off my 3" waste line for the toilet, I am teeing off to the other side of the room with a 2" pipe.The T is 4' from the toilet. Once to the other side (6')I will T to the right and left. 2x1 1/2 for the sinks and the tub. The 2" will continue straight up inside the wall and out the roof for venting. If a s trap is illegal in this case I will put everything in the wall and use a p trap. Just thought it would be easier to drill everything once when the vanity was in place. Thanks.

Granted, a "S" trap would be easier to install but to remain legal you're going to hafta run a vent on your vanity. Good luck, Tom

Hi Shulta

You CANNOT use Tee fittings on the horizontal piping to pick up fixtures, OK... WYES ONLY!

Also, how is the toilet being vented... individual vent or are you using the sink drain as a WET VENT for the toilet? If individual vent then a 2" vent is appropriate by code. If you will be wet venting the toilet using the lavatory drain then the lavatory drain and vent need to be 2" all the way until you can connect into a 2" or larger vent, OK?

If this doesn't make much sense, draw up a layout for your bathroom fixtures and post it here and we'll see if we can draw up the waste and vent as required by code. Oh yeah, what plumbing code prevails in your area...let us know that, too, OK?

Finally, if you are trying to center the toilet as best as possible, then I might suggest going up as ytight to the joist as possible and if the joist is large enough you may be able to OFFSET the drain using an offset closet flange... requires a little height here, however, but glad to discuss more if you want... ;)

Back to you...

Mark

Tom, live in Atlanta, Georgia with a weekend log home in the mountains. Maybe we're mincing words here. Lets say I have a standard under sink 1 1/2" P trap that goes into a 2"wall connected drain pipe that then goes down, inside the wall into a wet vented drain. Acceptable? That's what I have in my Atlanta house. Now, instead of going into the wall cavity, the same p trap connects to 2" horizontal pipe for 4", turn it down through the floor and connect it to a wet vented drain, same as above. What's the difference between going 4" into a wall connection going down vs. 4" along the wall and then going down. Consider that there is a log wall. They did not require an AAV.

Thanks Tom and Mark( and everyone else). Mark sorry for the incorrect terminology and yes it will be a wet vent. As far as the toilet I was trying to center it on the wall, but I am going to leave the joist alone and just get the closet flange as close as possible. I just did not know if I had to leave a gap between the flange and joist. Thanks
shulta44
Ps I will try and draw something up and post. Thanks for everything.

Ma0641,

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I have a standard under sink 1 1/2" P trap that goes into a 2"wall connected drain pipe that then goes down, inside the wall into a wet vented drain.

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Unless that pipe goes up to a vent you have just described a illegal "S" trap.

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the same p trap connects to 2" horizontal pipe for 4", turn it down through the floor and connect it to a wet vented drain, same as above. What's the difference between going 4" into a wall connection going down vs. 4" along the wall and then going down.

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The operating word in both cases is "DOWN" If you come off a "P" trap and go down instead of up to a vent you have just converted your "P" trap into a "S" trap. No two ways about it. Will they work and drain? BYes! Are they legal? No they aren't. But, whatever works for you.
Good luck Tom.

Not sure if this picture helps. I am no artist. Sorry. shulta44

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I have a standard under sink 1 1/2" P trap that goes into a 2"wall connected drain pipe that then goes down, inside the wall into a wet vented drain.

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Unless you have a pipe that goes up to a vent you have just described a illegal "S" trap. Does you sink have a roof vent? Regards, Tom

So on the wet vent, the 2" pipe going to the roof for venting between the tub and sinks is not good enough. I should come off the top of the sink drains and tie back into the 2" vent pipe again. Sorry that 2" vent pipe that looks like it is bending to the left actually runs straight up between and to the roof. I certainly have no problem tieing into that above the sinks.
Thanks for all the input. It has been eye opening.