Moving toilet location in concrete slab.

Piperca · Sep 21, 2009

Okay, I know I'm not the brightest bulb in the shop when it comes to plumbing, so I do apologize for, what you might find to be, stupid questions ... but here's another ... LOL!

What is the minimum height a sink drain can be cut into the 3"" stack?

I have decided to cut out the conglomeration of sanitary tees, shown in the last photograph above, and start from scratch.

I researched and found that the vent must extend 6" above the overflow (or rim) of a sink, but I couldn't find anything that says it must remain there. Would it be possible to do what is depicted in the following sketch? If so, that would allow me to keep the plumbing chase low, depending on what the minimum might be for the sink drain.

The sketch shows the vent line extending up and looping back down to the plumbing chase level, then back up to meet the existing vent/stack ... similar to how an island vent system would work ... would this meet code?

Terry · Sep 21, 2009

A true island vent is drained.

You pictured loop would not drain.
A vent can be flat, but not dipped.

A lav trap arm can be up to 42" long.

Sponsor · 2022-01-29T12:20:58-0800

Piperca · Sep 21, 2009

Terry said:
A lav trap arm can be up to 42" long.

So, I can not have the sink eleven feet from the 3" stack? Am I understanding you correctly ... or 42" without a vent? Also, If I was to connect the vent and drain at the dip, would that work to drain the vent?

Piperca · Sep 21, 2009

Okay, maybe if someone takes a look at what I am doing, then you'll be able to better advise me. How would I go about adding this new vanity/sink area?

Frenchie · Sep 22, 2009

piperca said:
Okay, I know I'm not the brightest bulb in the shop when it comes to plumbing, so I do apologize for, what you might find to be, stupid questions ... but here's another ... LOL!

What is the minimum height a sink drain can be cut into the 3"" stack?

I have decided to cut out the conglomeration of sanitary tees, shown in the last photograph above, and start from scratch.

I researched and found that the vent must extend 6" above the overflow (or rim) of a sink, but I couldn't find anything that says it must remain there. Would it be possible to do what is depicted in the following sketch? If so, that would allow me to keep the plumbing chase low, depending on what the minimum might be for the sink drain.

Terry said:
A true island vent is drained.

You pictured loop would not drain.
A vent can be flat, but not dipped.

A lav trap arm can be up to 42" long.

Like this:

Piperca · Sep 22, 2009

Okay, I looked into it and found that loop venting is ONLY allowable in an island application ... looks like I'll have to plumb a vent up into the attic and over to the stack.

So, other than the vent, is there anything else I need to worry about? How about the water lines (hot and cold); should I run these through the attic or would running them with the drain in the plumbing chase be acceptable?

I wish there was a chat function on this site, it would make this a little easier ... LOL!

I won't be getting around to finishing up the plumbing until next week anyway. I leave for Chicago on Thursday to see my son graduate from Navy boot camp ... good boy!

hj · Sep 23, 2009

plumbing

From your postings I get the impression you are going to have a kludge by the time you get done. If the chase is going behind the shower will it not have to be as high as the shower or all the way to the ceiling? The vent should be 42" above the floor to be in compliance with most codes, since they specify, "6 inches above the sink, OR 42 inches above the floor, whichever is HIGHER."

Piperca · Sep 23, 2009

hj said:
From your postings I get the impression you are going to have a kludge by the time you get done."

Too funny, but I agree that is how it is looking.

The problem is that I've vaulted the ceiling in the bathroom on that side and I'd have to drill through three 2x4s on flat and two 2x6s on edge to run the vent pipe into the attic. As I said before, my wife wanted a ledge built into the shower for shampoo/conditioner bottles, etc, so I thought incorporating the chase into where I put the ledge was killing two birds with one stone.

42" is fine, I can do that. I had intended on running the hot/cold lines and the drain in there anyway, so raising the chase to accommodate the vent will be fine.

Can you see any other issues, before I stumble blindly into the swamp!

Piperca · Oct 3, 2009

Okay, my son graduated from Navy boot camp, so I'm back at the project!

How does this look ... okay?

The original pipe had 3/4" fall per foot, so I kept the same with the new pipe ... is that okay? The only issue I see is that the closet flange is off the level, but I hope I can finagle that when I'm attaching it to the pipe and floor ... any suggestions on this?

Next will be the drain and vent, but I'd like to get the okay before moving on ... thanks!

hj · Oct 4, 2009

bend

Put a "spacer" around the toilet riser before you pour the concrete, so you can use an "outside/over the pipe" flange. But you are wrong about the loop/yoke vent ONLY being for islands. I use them anytime I do not have a route from the sink to the roof, such as a sink with all windows over it and lally columns or posts at either end of the windows.

Piperca · Oct 4, 2009

Unfortunately, I can't get an over the pipe flange to work. The closet elbow is so close to the level of the floor that, when I use a coupler, I only have approximately 1 1/4" of pipe to connect to. I guess I could cut the flange shorter to make it fit ... is that allowable?

So you're saying a loop vent would work fine for my sink? If so, what size should the vent pipe be? I'm also putting a second sink on the same line, which will be within 12" of the main stack; will this be a problem?

Piperca · Oct 4, 2009

I poured the concrete. I used that quick drying stuff and it's pretty dry when mixed to the manufacturers specs ... didn't like it! Anyway, it's done! I left a space for an over the pipe closet flange ... just in case.

Also, I replaced the fittings on the stack to delete the washer trap and turned the sanitary tee to run the drain. It's 1-1/2", so I hope that'll be sufficient for the drain.

Piperca · Oct 4, 2009

Okay, someone please give me their opinion on this, so I can glue it together and be done with my dilemma ... thanks!

This is the stub out for the second sink trap that's next to the stack ... is this okay? I'm trying to keep the stub out as low as possible, since the line is already at 19" on center.

The only thing that I am concerned about is the 2" vent that I cut into. It services the sink, toilet and shower in the adjoining bathroom and also the kitchen sink. I have run a 1-1/2" vent from the new sink to the 2" existing. I have read that 2" can service 8 fixtures; is my layout okay?

Lakee911 · Oct 5, 2009

Should that 2" (maybe 1.5") pipe into the 4" stack be connected with a wye and not a tee?

Jason

Piperca · Oct 5, 2009

I don't know; I replaced exactly what was there and it was a sanitary tee. If you go to post #19, you'll see the original fitting; all I did was replace it with the same and turn it around. Other than that, will this suffice?

Iminaquagmire · Oct 5, 2009

It should be a sanitary tee. Does anything drain into the stack from above? That will tell you if your vent is OK or not.

Piperca · Oct 5, 2009

iminaquagmire said:
It should be a sanitary tee. Does anything drain into the stack from above? That will tell you if your vent is OK or not.

Nothing drains from above; it's a single story residence.

Iminaquagmire · Oct 5, 2009

http://i275.photobucket.com/albums/jj316/piperca/SDC11165.jpg?t=1254703371

This is okay except for the first drain off the stack. It doesn't have to turn up like that. Doing so will make it an s trap. I'm not sure what you mean about cutting into a 2" vent though.

Piperca · Oct 5, 2009

Let me explain. The attached picture shows the existing 2" vent highlighted in red, the new 1-1/2" vent in blue and the new 1-1/2" drain in green. The house is single story. The stack is 3". There is an adjoining bathroom to the right, which you can see in the photograph. The adjoining bathroom has a toilet, sink and bath. In that bathroom, there is a short stack (3" vent) that rises from behind that toilet for approximately 3', which terminates at the top with some type of cap that the 2" vent pipe runs to (the one highlighted in red). That 3" vent has the toilet, sink, bathtub and kitchen sink draining into it. Since this 3" vent does not go through the ceiling, the 2" vent (highlighted in red) connects it to the main stack in the bathroom I am remodeling. Does this make sense? If so, will what I've done work?

Also, I can drop the sanitary tee down a bit to lower the drain line. At the new sink location, it is sitting at 22" on center; is this too high?

So, what you're saying is I can terminate that first drain horizontally, too?

Iminaquagmire · Oct 5, 2009

Terminate the first drain horizontally. Your venting is fine.

Moving toilet location in concrete slab.

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