New drain line routing in half bath?

Pghsebring · Feb 27, 2011

I have a small half bath, 3' x 5' that we're redoing. Here is the current floorplan:

Now, the "west" wall had a toilet, the "north" wall had a sink. The "east" wall is an exterior wall. What i wanted to do was to move the sink on the "north" wall into the "northeast" corner, so, about 2' to the right. Here's what the "north" wall looks like now:

And here is what i want it to look like:

Here is a picture underneath it all looking EAST:

My joists are 2x10, and currently the sink drain goes "over" the ibeam and then meets up with the toilet. Because i want to put it in the corner, it will be close to that brick wall - so how do i make the sink drain meet with the toilet drain? What would you do here? There is only the one vent, btw. I plan on cutting that 3" stack and making everything pvc from the basement floor all the way up to the current galv vent.

Yes, i can rip up that wood floor and drywall out of the ceiling below, but always want to keep extra work to a minimum.

Thanks in advance for any help.

Shacko · Feb 27, 2011

If I understand what you want to do all I would do is extend the existing lav line to the right, add a vent and run it back to the existing vent and tie it in all on the same wall.

Keep in mind if you remove the existing cast iron you have to make sure that the galv. is supported before you cut anything or it may come crashing down.

Sponsor · 2022-01-29T12:20:58-0800

Pghsebring · Feb 27, 2011

I understand what you're saying - but two problems - one, the closet flange is broken off, everything leaks, etc - i want to replace the whole thing with pvc...

...that said, i should just use the same routing, just replace it in pvc, right? Extend the sink drain over the the right, leave the vent in the same place, etc? Makes a lot more sense than what i was going to do i think...will that new drain be close enough to the vent? Looks to be about 2 ft. And is the current installation legal, with an elbow that the p trap ties into? Everything i've ever done has a santee there.

I already replumbed the kitchen and was fine on the galv, i'll make sure this one doesn't come down either.

Dlarrivee · Feb 27, 2011

I think you should be able to redo all of that in PVC and simply move the drain into the next stud cavity... You'll end up using a santee in your repipe, I'm sure.

Pghsebring · Feb 27, 2011

One more question - is that 90 at the top of the stack in the last picture, near the wall, legal? Thanks.

hj · Feb 28, 2011

What is NOT legal is the combination Y-1/8 bend used to connect the sink drain to the vertical stack. And it becomes even "less legal" the farther the elbow is moved from the stack.

Pghsebring · Feb 28, 2011

hj said:
What is NOT legal is the combination Y-1/8 bend used to connect the sink drain to the vertical stack. And it becomes even "less legal" the farther the elbow is moved from the stack.

Right, i know i have to use a santee there.

My question is, is that elbow on top of the 3" stack in the last picture legal? The one close to the wall? Do i just throw a long sweep on there and call it a day? Right now the stack comes straight up from the basement floor, and right before it hits the basement ceiling, it makes a 90 towards the toilet - is that fine?

PM5K · Feb 28, 2011

I'm no expert so I don't know if it's legal but either way knowing what little I know about plumbing I probably wouldn't want to use it even if it was legal.

So you want to move the drain but not the supply lines? I assume that's going to work with your sink, but I'm wondering how? Is it a pedestal, or a corner type?

Pghsebring · Feb 28, 2011

No, i'm gonna move the supply lines too, but that's a lot easier than moving the drain lines...drains rely on gravity, etc...the supply lines are under pressure, so the water will get there one way or another...

The supply lines just need to be extending a couple feet below, make a 90 right, and a 90 up. And if i run into problems, i'll be back on here asking...

As for the 90 on top of the stack, i can't think of anything else to do to get rid of it...i'm open to suggestions...but i have to keep that stack against the wall because of the cars that park below this bathroom.

Pghsebring · Mar 1, 2011

Alright, this is what i'm planning, any last words?

And which is better, a closet flange that is a 4"/3" where you put the 3" pipe inside it, or one that is 3" that the pipe goes outside of it? I know the second is slightly more narrow, but the lip of the pipe is on the inside of the 4"/3" universal one...i plan on getting a closet flange with a stainless ring either way...right? So which one would you choose for your house? Yes, it has to be 3".

PS. I realize "horizontal" is actually pitched a quarter inch per foot...

Pghsebring · Mar 7, 2011

Alright, so this is where we're at:

Few things i learned. First, i'm gonna have to use an offset closet flange because of that heating duct. Second, the old toilet drain leaked so much now i have to do a repair to the rust hole in the galvanized heating duct.

Now, i want to move the water lines. Currently they were installed flat against the bottom of the joists, and then a layer of drywall/hardcoat was put on the ceiling so as to fully cover them up. You can kind of see the water lines in this picture:

Now, what i want to do is move them to the wall on the right side of the picture. I want to know, can i just put a 90 off of them where they turn vertical, then reroute them like this:

Anyone have a better idea? Worst part is trying to drill into those joists, i'm gonna have to use a coupler for each copper line at some point in there... Is this plan fine? Or could you describe a better one?

Thanks in advance.

Jadnashua · Mar 8, 2011

Pex might be easier to run, then only one connector at each end. Not all offset toilet flanges are created equal. Do not use the type that has essentially a shelf, get one that goes down at an angle and you have a chance it won't get clogged frequently. Could you change that section of ductwork to rectangular verses the square? That might give you the room you need to use a conventional flange.

Pghsebring · Mar 8, 2011

jadnashua said:
Pex might be easier to run, then only one connector at each end. Not all offset toilet flanges are created equal. Do not use the type that has essentially a shelf, get one that goes down at an angle and you have a chance it won't get clogged frequently. Could you change that section of ductwork to rectangular verses the square? That might give you the room you need to use a conventional flange.

None of the ductwork in this house is standard, i can't find anything that'll fit in the local box stores. I try not to mess with it anymore, even though it was poorly planned/installed. If it wasn't so damn expensive, i'd rip it all out and replace all of it.

The other choice is to leave an inch behind the toilet like they did before...

I've never run pex before, and just stuck with copper because that's what was here when i started...how do i transition to pex? Does it work better than copper, last as long, not leak any more easily, etc? Do i need more tools? If i was plumbing a new house i'd think about using it - you don't have to run it on the bottom of joists, etc - but i'm just not sure about using it here and in the other bathroom i'm redoing...

Jadnashua · Mar 8, 2011

To do pex, at the minimum, you'd need a crimping tool. Solder on a barbed fitting on the copper, slide the pex over it, crimp and that connection is done. Now, my preference is the expansion system, but the tool is a lot more expensive. You can get a pex crimp tool pretty inexpensive, the expansion tool (used on Uphonor pex) is more expensive.

Pghsebring · Mar 9, 2011

But it's not illegal (codewise) to get out my torch (that i already own) and solder some 90s on there and route the plumbing like i diagrammed? I know its kind of convoluted...but if not illegal, that would be most cost effective for me...

...or do i have to cut back further in the copper line and start from there?

And what's the standard rough in height for the water supply? I don't have a sink picked out yet...

How much pipe do you put above the T to prevent water hammer?

Jadnashua · Mar 9, 2011

There's no code issue with the copper. The more connections, the greater the possibility of a leak, but if done properly, not an issue. When penetrating structural members, there are some code issues, and nail plates, etc. may be required, depending on where it is run to help prevent fastener damage.

There is no real standard for either a toilet or a sink supply location. Some of it depends on the fixtures you choose so that you can get the supply hoses fit, and, depending on what you intend, whether they can be hidden (critical on a pedestal sink). Some toilets require things in certain places, but you may or may not choose one of those toilets. Best to decide on the fixtures, then put the supplies in the right place, rather than having to move it, or have less than optimal positioning later.

Pghsebring · Mar 15, 2011

Ok, the supply lines are in.

A question about the drain lines - there is a 90 attached to the bottom of the closet flange, and then the 3" drain goes horizontal for a while. I want to hang the new drywall on the basement ceilling before i put the drain lines in - because it will be easier to finish the drywall later. That said, what is the best way to support a horizontal run of 3" pvc just beneath a drywall ceiling? Do i cut a couple slits in the drywall near the joists and use plastic hanger tape (i can nail from above into sides of joists, floor is removed)? What is the code here for type/spacing of hangers? I have a 4 ft or so run of 3".

Pghsebring · Mar 16, 2011

Bump for answers.

Cacher_Chick · Mar 16, 2011

A 4' run only needs one hangar, but I would use two depending on the layout.

I would frame and drywall AROUND the pipe, not leave it exposed below a finished ceiling.

Pghsebring · Mar 18, 2011

The ceiling is only finished because its a garage ceiling, code for fire i believe.

And do you mean those J hangers, or can i use plastic hanger tape?

Newest question: where can i cut this vent stack legally to replace everything below it with pvc, then tie in with shielded fernco? How many inches above the floor? Or is it just above the sink rim, or ?

New drain line routing in half bath?

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