Adding 1st Half Bath. Need Help With Drain Line (Photos and Drawings Attached)

[Joe D]

Hi Guys,

I'm looking to add a 1/2 bath on the 1st floor. I'm thinking about doing the plumbing work myself but need some advice from the plumbing pros. I have included pictures and layouts on how I am thinking about running my drain lines. I plan on running the drains under the floor joists since I have heating and cooling duct work in between the joists. The other thing is I have a 8" thick brick wall that I am really trying to avoid drilling through (this is why I plan on running through the old window slot (see drawing). I plan on using ABS piping since that is the material of

Questions I have.
1. Does my drain plan look ok to an experienced plumber?
2. I plan on venting the toilet with the sink vent through the roof. Is this correct? Can I use an air admittance valve instead of going through the roof?
3. My toilet is going to be approx 15' from the main stack. Is this too far? All lines will slope 1/4" per 12" except when I get to the final connection in the main stack. The final connection will have a large slope on it. My main drain will not be in a straight line. It will need to go back through the wall opening to reach my main stack. This is to avoid drilling a 3" hole through my 8" brick wall.
4. My sink drain and sink vent is going to be 2" connecting into the 3" toilet drain.
5. Should I add any cleanouts? If so, where?
6. I have approx 11" vertical drop right after the toilet flange before it reaches the 1st 90. This is to avoid hitting my ducts. Is that ok?
7. Any suggestions on fittings, layout, venting? Anything, I'm all ears. Thanks in advance.

 

[MicEd69]

1. Does my drain plan look ok to an experienced plumber?

I'm an engineer not a plumber, but my answer is almost. See comments below.

2. I plan on venting the toilet with the sink vent through the roof. Is this correct?

Yes.

Can I use an air admittance valve instead of going through the roof?

Not advisable.

3. My toilet is going to be approx 15' from the main stack. Is this too far?

No.

All lines will slope 1/4" per 12" except when I get to the final connection in the main stack. The final connection will have a large slope on it.

Your one sketch looks like this is a 445 degree slope. If it is, this should be OK. But slopes more than 1/4" per foot and less than say a 45 degree slope, the water will flow out fast and not carry all the solids with it. That can result in sewer line blockage, so keep/make that a 45 degree slope.

My main drain will not be in a straight line. It will need to go back through the wall opening to reach my main stack. This is to avoid drilling a 3" hole through my 8" brick wall.

4. My sink drain and sink vent is going to be 2" connecting into the 3" toilet drain.

This is acceptable; however, you call the connecting fitting a Sanitary Wye. There isn't such a fitting, rather it is a reducing wye. And that wye needs to enter the 3" line vertically or no more than 45 degrees off vertical. That might be an issue for you with this layout.

5. Should I add any cleanouts? If so, where?

You might want on in the vertical line from the sink P-trap. And in the 3" line, the first 90 after the sink connection maybe should be a tee to act as a cleanout.

6. I have approx 11" vertical drop right after the toilet flange before it reaches the 1st 90. This is to avoid hitting my ducts. Is that ok?

Yes, and while it isn;t required, I would suggest a long radius 90 at that location.

7. Any suggestions on fittings, layout, venting? Anything, I'm all ears. Thanks in advance.

 

[Joe D]

1. Does my drain plan look ok to an experienced plumber?

I'm an engineer not a plumber, but my answer is almost. See comments below.

2. I plan on venting the toilet with the sink vent through the roof. Is this correct?

Yes.

Can I use an air admittance valve instead of going through the roof?

Not advisable.

3. My toilet is going to be approx 15' from the main stack. Is this too far?

No.

All lines will slope 1/4" per 12" except when I get to the final connection in the main stack. The final connection will have a large slope on it.

Your one sketch looks like this is a 445 degree slope. If it is, this should be OK. But slopes more than 1/4" per foot and less than say a 45 degree slope, the water will flow out fast and not carry all the solids with it. That can result in sewer line blockage, so keep/make that a 45 degree slope.

My main drain will not be in a straight line. It will need to go back through the wall opening to reach my main stack. This is to avoid drilling a 3" hole through my 8" brick wall.

4. My sink drain and sink vent is going to be 2" connecting into the 3" toilet drain.

This is acceptable; however, you call the connecting fitting a Sanitary Wye. There isn't such a fitting, rather it is a reducing wye. And that wye needs to enter the 3" line vertically or no more than 45 degrees off vertical. That might be an issue for you with this layout.

5. Should I add any cleanouts? If so, where?

You might want on in the vertical line from the sink P-trap. And in the 3" line, the first 90 after the sink connection maybe should be a tee to act as a cleanout.

6. I have approx 11" vertical drop right after the toilet flange before it reaches the 1st 90. This is to avoid hitting my ducts. Is that ok?

Yes, and while it isn;t required, I would suggest a long radius 90 at that location.

7. Any suggestions on fittings, layout, venting? Anything, I'm all ears. Thanks in advance.

MCED69,

Thank you so much for your response. I confirmed the slope going to the main stack is at 45 degrees. I also added the cleanouts where I think you told me to. I did add one under the toilet as well. Also, i plumbed the 2" sink drain/wet vent vertical to the 3" pipe run. I did have to lower the 3" line down a few more inches to get my 1/4" slope. I will have to duck a bit when walking through the door (bottom of pipe is approx 5'6" from the floor). I think I can live with that to have a half bath on the first floor. Thanks for your help and let me know if i screwed something up.

 

[Twowaxhack]

Don’t lay sanitary tees down on their backs that accept waste water and horizontal to horizontal drainage should be done with long sweep 90’s or equivalent if your making a 90.

 

[MicEd69]

You may have misread my original response. I said, "you call the connecting fitting a Sanitary Wye. There isn't such a fitting, rather it is a reducing wye."

From your sketch, it appears you are using Sanitary tees for the cleanouts in the 3" line as well as the connection from the sink instead of the reducing wye that I mentioned in my response. As Twowachack said, Sanitary tees are not the correct fitting for those locations. You should use a 3" combo fitting under the toilet and at the first 90.



For the 2" drain connection to the 3" line, you need to use a reducing wye.



Install this with the 2" branch angled towards your sink location and rotate it so the branch is 45 degrees off vertical. That will likely reduce how far you have to lower the 3" line to get the 1/4" slope required for your sink drain line, and this is the correct fitting to use for that connection.

 

[Pipe Dreams]

Hi Guys,

I'm looking to add a 1/2 bath on the 1st floor. I'm thinking about doing the plumbing work myself but need some advice from the plumbing pros. I have included pictures and layouts on how I am thinking about running my drain lines. I plan on running the drains under the floor joists since I have heating and cooling duct work in between the joists. The other thing is I have a 8" thick brick wall that I am really trying to avoid drilling through (this is why I plan on running through the old window slot (see drawing). I plan on using ABS piping since that is the material of

Questions I have.
1. Does my drain plan look ok to an experienced plumber?
2. I plan on venting the toilet with the sink vent through the roof. Is this correct? Can I use an air admittance valve instead of going through the roof?
3. My toilet is going to be approx 15' from the main stack. Is this too far? All lines will slope 1/4" per 12" except when I get to the final connection in the main stack. The final connection will have a large slope on it. My main drain will not be in a straight line. It will need to go back through the wall opening to reach my main stack. This is to avoid drilling a 3" hole through my 8" brick wall.
4. My sink drain and sink vent is going to be 2" connecting into the 3" toilet drain.
5. Should I add any cleanouts? If so, where?
6. I have approx 11" vertical drop right after the toilet flange before it reaches the 1st 90. This is to avoid hitting my ducts. Is that ok?
7. Any suggestions on fittings, layout, venting? Anything, I'm all ears. Thanks in advance.

1. looks fine by your drawings
2. yes, yes, but through the roof is better
3. no that does not matter
4. that is fine, no issue
5. not really, the toilet is one, and of course, are you going to run the sewer machine on a ladder? no.
6. yes, use a long sweep 90, will be better, but not needed. just a suggestion not a directive
7. Looks like a solid plan.