Moving toilet location and venting

[K9mlxj]

Hi there,

I have 2 bathrooms where the two toilets in both bathrooms sitting back to back, with the main vent located in the wall between the two toilets in the two bathrooms on each side of the wall.

Now I want to move the toilet in one bathroom about 20 inches to the left -- away from the main vent.

My question is,

do I need to add a new vent line where the toilet's new trap location joins the drain line -- that would run upward -- and join the continuous vent line that runs across the wall to the main vent?

If I do, it would be a 2" vent?

Or I don't really need a new vent line from the new toilet location?

The house was built in 1955, so it has cast iron drain pipe.

 

[hj]

we could answer your question IF we knew how you were going to run the pipe to the newe location.

 

[Sponsor]

 

[K9mlxj]

The main drain pipe runs along and right under the wall (in the crawl space) between the two bathrooms.


So to move the new toilet location 20 inches to the left away from the main vent (in Bathroom B),

I'd need to make a cut on the main drain pipe at a spot under and behind the new toilet location, then run a new waste line (black line) right from the the cut out to the toilet's roughin spot.

Top view:

Also there is a support beam next to the new toilet location. What's the min. required spacing (code) between the new waste line for the toilet and the support beam?


The new location is near where the bathroom sink was. Essentially, I'm swapping the locations of the bathroom sink and the toilet.

 

[K9mlxj]

Any expert advice?

 

[K9mlxj]

I've added a couple of pictures see if that would help.

I am expanding the shower so it's wider shower. Because of this, I cannot use the same spot where the bath sink is now for the new toilet location.


Also, there is a support beam right next under the sink, so I need to have the new toilet location 4" further over to the right, where the red circle is.

This is how it looks in the crawl space (picture is taken from the view from the other bathroom):

This shows the two current toilet drain pipes and the main vent in the middle. The toilet drain w/ a red cross mark is the one to be removed.

New toilet location:

solid red circle = new toilet locaiton
hollow red circle = add new vent (up) -- if I do need to add a new vent for the new toilet location.

Note the new toilet location will be sitting next to left of the support beam.

Main thing is if I need to add a new vent.

If I do,
it'd be right at the hot water line location of the existing vanity faucet (meaning I need to move that pipe out...).

Notice the support beam to the right of the hot water pipe... .

This is a view from the other bathroom (I opened up the wall), where you'd see where the existing hot water pipe comes up.

You'd see a stud to the left of the hot water pipe, and the support beam to the right of the hot water pipe.

There's about only 2 1/2" space between the stud and the support beam -- barely enough space if I need to push a vent up between the stud and the support beam.

This means the new vent line would go right between the stud the support beam with little spacing.

Would that be a violation of code?

Do I need to add a vent for the new toilet location?

If I dont't it'd save some work to redo the hot water piping. Plus the space where the hot water pipe comes up is very tight, barely fits the 2" vent I need for the new toilet location.

 

[Terry]

The arm for the toilet can be up to six feet long.
All you need to do is to extend the line 20" farther. You're golden.

 

[K9mlxj]

The arm for the toilet can be up to six feet long.
All you need to do is to extend the line 20" farther. You're golden.

Hallelujah! So no need to add another vent line -- just replace the toilet drain line with a new drain line to point at an angle -- to the new toilet location instead--!!

That saves me a LOT of work!


Thx Terry!

 

[K9mlxj]

One last question:

To comply with code, does the toilet arm need to be a little away from the support beam -- like 2 inch spacing?

Thx.

 

[Terry]

The toilet arm can touch the beam.

I see some pipe threaded into drop ear 90's. While it is open, it's a good time to replace galvanized if that is what they are.

 

[K9mlxj]

Thx. Yea I plan to replace anything involved to ABS in this project.

 

[Terry]

Thx. Yea I plan to replace anything involved to ABS in this project.

I was thinking of the copper water lines and the threaded nipple there.

 

[K9mlxj]

I think it's brass (I think I changed out the nipples coming out from the walls to all brass a couple of years back -- before the price jumped... ) -- but I'll double check.


BTW, I didn't quite measure it,

I want to see that I can use a stack configuration like this so the two 4" sanitary tee's to both toilet trap arms can share the main vent -- not sure if there's enough vertical space for the two 4" sanitary tee's.


Let me know if my thinking is correct.


Or I'd need to make a cut on the main drain pipe for the new toilet trap arm to connect to like I thought before.

 

[Terry]

3" works fine for the two toilets.
Sometimes I install these at a 45 degree angle if I don't have much vertical space.
Or you could wet vent the second toilet with a lav.

A basic drawing. I like to use wyes and 45's on the horizontal.

 

[hj]

Cut the closet bend off, connect a 90 elbow to it and run to the new toilet location with a new closet bend. IT would take less space if you did it in cast iron.

 

[K9mlxj]

Thx for the two different ideas!

I'll definitely replace the cast iron with ABS as occasionally I still have occasional clogs perhaps the cast iron pipe inner lining isn't that smooth.


I have AS Cadet 3 toilets in both bathrooms now (one is a 1.28gpf in the other bathroom it is 1.6gpf).

 

[K9mlxj]

If I use double combo wye (two toilets) + wet vent (one lav) that would work? Or too congested for the two Cadet 3 (3" flush valve) toilets nowadays?

I think I'd use 4" x 4" x 3" x 3 " double combo wye to ensure there's plenty of room for draining both toilets (a reducer above the double wye). Is that overkill?

With this double combo wye, could water be still pushed out to the other side when flushing one toilet (3" flush valve)?

 

[K9mlxj]

I have a question on wet venting :

If I wet vent one toilet and one lav, the vertical space I need is about 25 3/4" ( 4"-3" Long Wye + 3" Long Wye + 90 deg elbow to toilet flange) + 1/4" for slope, i.e. 26" total vertical space.


The crawl space is about 24" height. So I'd need the main drain to be around 2" below dirt to allow for enough vertical space.

Right now the CI main drain is seated a bit below dirt. So it seems the vertical spacing available for the wet vent setup is pretty tight.

Is wet vent doable?

 

[Cool Blue Harley]

I believe HJ and Terry are telling you the same thing. Are you going to cut out the entire double fixture fitting? That's a lot of work. Cut the iron pipe on the arm of the double fixture fitting for your new proposed toilet one inch from the hub and spigot, lead and oakum joint. That one inch will allow you to install a CP 44, old iron to new iron, mission coupling. The 1/4 bend to the new location needs to be what we call a medium sweep because of the horizontal orientation. You will also need a 4x6x12 or 4x12x12 herco bend and a 4x2 insta-set closet flange. Secure the pipe to the beam with a four inch strap. Don't forget your 1/4 inch per foot grade. You could put a 4x3 NH coupling at the hub and spigot cut and run it in 3 inch. Might be easier. You could also convert to ABS with the same coupling, even easier yet again. Moving a toilet a little bit is challenging. Like Terry said, you have 6 feet from the flange to the inner edge of the vent on a toilet. Greater distances are less challenging.
Not sure about your wet vent question. It's called vertical wet venting. You could wet vent your lavatory drain into the four inch vertical stack if you cut in a 4x2 tee about 20 inches off the floor in your bathroom above. You then can go a maximum of 42 inches to your sink. (If 1&1/2 inch arm)

 

[K9mlxj]

For the wet vent I was referring to Terry's idea "Or you could wet vent the second toilet with a lav."

Although, the crawl space height was only 24" so spacing was tight. So right now I opt to go by Terry's layout of going horizontal for both toilets instead. This is a lot more space than trying to tie the toilet to the main stack in the crawl space.

I'd cut out the double fixture fitting. Looking at Terry's layout the spots where the toilet drains join the main drain are further away so that allow for more space to layout the pipes.


I took some pics of the layout.


For the relocated toilet (on the left side; the main stack to the right where the toilet was tied to before):

For the 2nd toilet (in the other bathroom, location unchanged).

A couple of things:

- I used 4" drain for the toilet
- I used 90 deg long elbow to reduce the chance of clog
- The top of the horizontal run of the toilet waste arm was about 16" above ground. There would be enough clearance to work with the 5 1/2"h x3 1/2" d beam in the 24" crawl space.
- I rotated the long-turn tee wye to the waste arm up a bit (see last pic) to assure there's no belly where it joined the main drain.
- I opened up a small hole into the bathroom wall and I noticed the main stack was a 2" cast iron pipe.
- the pics showed 3" main stack size. I guess it's ok to keep the 2" CI main stack?

Let me know if everything looks good.

 

[K9mlxj]

I didn't think about this when I rotated the long wye : a slope of a drain line must be either 1/4"/ft max or > 45 deg.


The distance from the center of the main drain to the center of the toilet flange is 12" rough-in + 1/2" trim + 1/2" (dry wall thickness) + (5 1/2" inner wall space)/2 = 15 3/4".

So I'd need to raise up one end of the long wye to 15 3/4" to get to 45 deg slope.

This makes it up close to the bottom of the beam.


Layout 2: So I'm looking into the simpler horizontal layout

Layout 3: If I split the 90 deg elbow to 2x45 deg elbows, would it drain faster/better because of the 45 deg slope?