Bath DWV for 2nd floor bath

[RobblePlumbing]

Any suggestions or comments are greatly appreciated! I attached images of the original configuration in case it was useful and a potential new plan.

While renovating a second floor bathroom I am going to be swapping the location of the sink and stand up shower (and replacing the stand up shower with a bathtub).

I am not sure how to route the new sink drain line since there's a galvanized steel (or cast iron) vent pipe on the way to the 3" drain pipe. The bathroom below on the 1st floor is already wet venting its sink so I can't tie the second floor sink into it.

I have the room to route a drain line from the sink over to the bathtub run, but I'll have to make a 180 degree turn into it. Is this acceptable? I have the room within the floor to do since the first floor has an empty soffit there.

There's a 3" sanitary tee with a double inlet online, but it doesn't look like it's sold locally so I'm assuming it's not up to code, but I don't know.

Another option is to run a drain pipe from the sink straight down to the basement and then tie into my 3" drain down there.

Is there something that I should be doing differently or a preference on how to solve this?

Thank you!

 

[wwhitney]

Your diagrams are hard to follow, for me at least, because of mixing horizontal and vertical segments. How about a diagram that is just in plan view (all dimensions horizontal), where a vertical segment just shows up as its projected circular cross section? Perhaps with some annotations about any critical vertical connectivity that is thereby obscured.

Cheers, Wayne

 

[Sponsor]

 

[RobblePlumbing]

Your diagrams are hard to follow, for me at least, because of mixing horizontal and vertical segments. How about a diagram that is just in plan view (all dimensions horizontal), where a vertical segment just shows up as its projected circular cross section? Perhaps with some annotations about any critical vertical connectivity that is thereby obscured.

Cheers, Wayne

Wayne,

Below I added a picture of what I think you are looking for and also a picture of the actual room.

 

[wwhitney]

Looks like you have a fair amount of subfloor to patch. It's important to separate the stud bays from the floor joist bays, that's a fireblocking requirement. So after all the rough work and patching the subfloor and wall plate, use fireblocking foam around all the penetrations in the wall plate.

As to your question, the simple option would be to pass a 1-1/4" or 1-1/2" sink trap arm across the front (or behind) the galvanized vent, to hit a san-tee on the copper DWV. But that would require you to fur out the wall framing to maybe 4.5" thick, which I assume you don't want to do.

One option would be to jog the 2" vent pipe to the right down low in the wall, until it is maybe 12" past the near edge of your sink cabinet. That way the sink trap arm could enter the wall to the left of the vent pipe and reach a san-tee in copper DWV. The 2" vent would jog back to the left higher up in the wall.

A completely different approach would be to use the lavatory drain for horizontal wet venting the WC and shower. For that, you'd have a san-tee in the wall behind your sink, with the vent rising to at least 6" above the sink flood rim before joining up with the galvanized vent. The drain would enter the floor system, and the sink, shower and WC drains would join up before the combined drain turns down with an elbow at the location of the current cast copper 3x2x3 (?) san-tee. The vent connection currently from the top of the san-tee to the galvanized would no longer be required.

For horizontal wet venting, the sink drain (wet vent) has to join either the WC or shower individually, and then the combined drain can joint the other fixture (shower or WC, respectively).

Cheers, Wayne

 

[RobblePlumbing]

Looks like you have a fair amount of subfloor to patch. It's important to separate the stud bays from the floor joist bays, that's a fireblocking requirement. So after all the rough work and patching the subfloor and wall plate, use fireblocking foam around all the penetrations in the wall plate.

As to your question, the simple option would be to pass a 1-1/4" or 1-1/2" sink trap arm across the front (or behind) the galvanized vent, to hit a san-tee on the copper DWV. But that would require you to fur out the wall framing to maybe 4.5" thick, which I assume you don't want to do.

One option would be to jog the 2" vent pipe to the right down low in the wall, until it is maybe 12" past the near edge of your sink cabinet. That way the sink trap arm could enter the wall to the left of the vent pipe and reach a san-tee in copper DWV. The 2" vent would jog back to the left higher up in the wall.

A completely different approach would be to use the lavatory drain for horizontal wet venting the WC and shower. For that, you'd have a san-tee in the wall behind your sink, with the vent rising to at least 6" above the sink flood rim before joining up with the galvanized vent. The drain would enter the floor system, and the sink, shower and WC drains would join up before the combined drain turns down with an elbow at the location of the current cast copper 3x2x3 (?) san-tee. The vent connection currently from the top of the san-tee to the galvanized would no longer be required.

For horizontal wet venting, the sink drain (wet vent) has to join either the WC or shower individually, and then the combined drain can joint the other fixture (shower or WC, respectively).

Cheers, Wayne

Yes, I found there were a few extra holes in the floor after I took off the second layer of subfloor. The footer for that wall is not laying on a joist so I'm assuming I would still need some kind of fire block up to the next joist which runs parallel with the wall.

Firing out the wall is not desirable because I see this causing issues later down the line even though it's only another inch.

I like the idea of jogging the vent pipe over to the right. I would also have to be careful with running the new waterlines so they don't interfere. What would be the maximum angle that I can add a turn like that? 45 degrees to the right and then 45 degrees back to the left?

Your last recommendation was something I considered, but when dry fitting the toilet pieces I found it pushed my toilet rough in too far from the wall. I was using a double sanitary tee laid horizontally (3x3x2x2) between the closet bend and the 3" copper drain. I may revisit this if I decide to change that 3" drain pipe all to PVC. Part of the problem was that I have to shift the toilet over and the extra pieces to make the turn were also adding to my toilet distance from the wall. I was also reading about how it could be difficult to get the horizontal double sanitary tee perfectly level to tie in drains from both sides at the right pitch.

After seeing my picture and new drawing, did you have any thoughts on running my sink drain through the floor over to the bath drain and connecting with a sanitary tee or a long sweep wye? I have room in the floor to run behind the galvanized pipe and the 3" copper pipe because there's an empty soffit on the 1st floor. Here's a drawing looking down at the plumbing. I'm pretty sure I would also need to connect the vent pipe from the sink drain with a sanitary tee at the sink. Is this kind of a turn acceptable? The wye would not lay perfectly horizontal like shown in the picture because I would need to keep the slope from the sink over to the 2" drain.

 

[wwhitney]

I like the idea of jogging the vent pipe over to the right. I would also have to be careful with running the new waterlines so they don't interfere. What would be the maximum angle that I can add a turn like that? 45 degrees to the right and then 45 degrees back to the left?

The answer depends on the height of the bends in the vent pipe, relative to the flood rim level of the fixtures it serves. 45 degrees is still considered vertical, so you can do that at any height. But if the vent is at least 6" above the flood rim of all fixtures it serves, you can use 90 degree bends to go horizontal. Thus if that galvanized vent is only for downstairs fixtures, you can use 90 degree bends. Which I would recommend so you can drill straight through the studs.

Also, you mention horizontal san-tees a few times. If you have a drainage fitting with 3 openings, and all 3 are drains (2 in, 1 out), and any two of the openings are horizontal, it's not allowed to be a san-tee. It should be a wye or a combo.

Your drawing where the sink drain does 270 degrees of turning in plan is likely allowed, and may trigger some cleanout requirements, but I would think other options would be better than having so many bends.

Cheers, Wayne

 

[RobblePlumbing]

The answer depends on the height of the bends in the vent pipe, relative to the flood rim level of the fixtures it serves. 45 degrees is still considered vertical, so you can do that at any height. But if the vent is at least 6" above the flood rim of all fixtures it serves, you can use 90 degree bends to go horizontal. Thus if that galvanized vent is only for downstairs fixtures, you can use 90 degree bends. Which I would recommend so you can drill straight through the studs.

Also, you mention horizontal san-tees a few times. If you have a drainage fitting with 3 openings, and all 3 are drains (2 in, 1 out), and any two of the openings are horizontal, it's not allowed to be a san-tee. It should be a wye or a combo.

Your drawing where the sink drain does 270 degrees of turning in plan is likely allowed, and may trigger some cleanout requirements, but I would think other options would be better than having so many bends.

Cheers, Wayne

I'm leaning towards jogging out the vent pipe as you suggested. I have another drawing below that shows a 2-D view from the side so I can show each floor of the house. From what I can tell, the 1st floor bath and toilet looks like it relies on the 2" vent that goes up to the roof for venting, but it's connected at the main sewer line before leaving the house. Everything is open in the basement, the second floor, the attic and I snaked a camera where I don't have the walls open on the first floor to confirm my drawing. There has never been any issues with the first floor bathroom so it seems to work.

How does this look?

 

[wwhitney]

Everything below the line separating 1st floor and basement, is that arrangement vertical as your drawings suggests (A), or is everything horizontal (B)?

(A) As drawn, the 1st floor tub and WC are not vented. The top of the "main waste line to sewer" should have a vent coming off that reconnects to the 2" galvanized vent line no lower than 6" above the flood rim of all the 1st floor fixtures.

(B) That's almost a good horizontal wet vent for the 1st floor bathroom, but the order of connection to the "main waste line to the sewer" should be, going downstream, sink meets tub or WC; then WC or tub, respectively; and finally the 3" drain line from the 2nd floor.

Cheers, Wayne

 

[RobblePlumbing]

Everything below the line separating 1st floor and basement, is that arrangement vertical as your drawings suggests (A), or is everything horizontal (B)?

(A) As drawn, the 1st floor tub and WC are not vented. The top of the "main waste line to sewer" should have a vent coming off that reconnects to the 2" galvanized vent line no lower than 6" above the flood rim of all the 1st floor fixtures.

(B) That's almost a good horizontal wet vent for the 1st floor bathroom, but the order of connection to the "main waste line to the sewer" should be, going downstream, sink meets tub or WC; then WC or tub, respectively; and finally the 3" drain line from the 2nd floor.

Cheers, Wayne

Ah, I see your point. I didn't give good detail for the basement connections, but I was only trying to get across that everything connects in the basement in some fashion to the main waste line. The picture was to show everything on the 1st and 2nd floor from a side view as if you were standing outside the house looking in.

The 1st floor bathtub p-trap is located in the basement and the "main waste line to sewer" does have the 2" galvanized pipe 6" above the p-trap. The first floor toilet must also be utilizing that as the vent pipe. Everything on the first floor has been working great for years, so I'm going to assume it's a non-issue (for now).

As far as the second floor goes that I'm renovating, do you see any issues with the new DWV configuration?

Thank you for all your feedback and suggestions! I greatly appreciate it

 

[wwhitney]

Second floor drawing matches what we've been discussing, I don't see any issues there.

Cheers, Wayne