80 year old bath remodel

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Rich_Davison

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Bath remodel on 80 year old house. Southwest Michigan
This house was apparently built before public utilities and the bath added when public water and sewer arrived. It essentially unchanged since then. I have included sketches which I hope show clearly my intentions. Basically new fixture locations and all new DWV. Intention is use a wet vent from the lav to serve the toilet and shower with kitchen sink drain downstream with it's own vent. Primary obstacles include shallow crawl space and the depth of the bath.


Questions/points as follows:
1. Main drain collecting the lav, shower, and toilet in that order and the closeness of the wye's to each other.


2. Intend to hold the drain up next to the bottom of the joists.

3. Drain will empty into the original C.I. sewer by dropping straight down about 3ft.. Connection using a Donut by Fernco. Also intend to use a Fernco coupling in the PVC downpipe to allow insertion of the last piece into the C.I.

4. The lav drain will have to go through the floor since the wall is the original house exterior and has two joists under the plate.

5. 2" drains from the lav and shower will enter 3" main by wye's rotated to the flat/0 deg. position. Length of runs marked on sketch. I intend to use long sweeps everywhere except possibly at the last downturn into the sewer.(any opinion?)

6. There will be a kitchen drain between the toilet and the downturn to the sewer. Are there any particular cautions to how I add this? I intend to take a second vent up alongside the lav vent and connect them in the attic and then outside.

Thank you in advance for any and all help.
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wwhitney

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Michigan is on the IPC, per up.codes. Your drawings are very neat and clear, and I see no problems.

1) IPC doesn't require that the WC be last, FWIW. No code problems with the closeness of the wyes/combos. The lav drain can be 1-1/2" up until it hits the 3" section, if desired.

2) You can start the lav drain near the bottom of the joists, but with the required 2% slope you'll be a little lower at the end. I.e. if the center line of the lav is 1-1/2" below the joists at the beginning, it looks to be 10' of run or so to the final turn from horizontal to vertical, so you'd be at center line 4" below the joists by then.

3) You could in theory do it without the Fernco coupling, by building the DWV starting at the existing CI. But there's no reason to make it hard on yourself, the Fernco coupling will probably be some useful flexibility. The type of coupling required depends on whether it is above or below grade: above grade is a ~2" long coupling with a shield; below grade is an ~4" long coupling with or without a shield.

4) If you have a vanity, you can still put most of the piping in the wall if you want, and just kick out of the wall with a 45 into the vanity toe kick space to avoid the double joist, entering the floor system at a 45.

5) For horizontal to vertical either medium or long turn quarter bends are allowed. When you have the space for either, not sure if there is a reason to prefer one or the other.

6) Both vents can be 1-1/2". I don't see anything about your layout that would give rise to specific concerns about your kitchen sink.

No washing machine standpipe?

Cheers, Wayne
 

Tuttles Revenge

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IPC doesn't require a 2" vent for that horizontal wet vent system? I'll defer to Waynes knowledge in that dept..

When we have rim joists that we need to work around, we run the sink drain in the wall, notch the plate and go thru the floor at a 45deg that stays under the toe kick of the cabinet so that in the end you cant see it.

You would save $2 by using a medium sweep 90 over a long sweep and lose 1.5" in height to the vertical pipe. But it sounds like you have feet of room to play with in a crawler, so I don't think it matters at all.
 

Rich_Davison

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IPC doesn't require a 2" vent for that horizontal wet vent system? I'll defer to Waynes knowledge in that dept..

When we have rim joists that we need to work around, we run the sink drain in the wall, notch the plate and go thru the floor at a 45deg that stays under the toe kick of the cabinet so that in the end you cant see it.

You would save $2 by using a medium sweep 90 over a long sweep and lose 1.5" in height to the vertical pipe. But it sounds like you have feet of room to play with in a crawler, so I don't think it matters at all.
Michigan is on the IPC, per up.codes. Your drawings are very neat and clear, and I see no problems.

1) IPC doesn't require that the WC be last, FWIW. No code problems with the closeness of the wyes/combos. The lav drain can be 1-1/2" up until it hits the 3" section, if desired.

2) You can start the lav drain near the bottom of the joists, but with the required 2% slope you'll be a little lower at the end. I.e. if the center line of the lav is 1-1/2" below the joists at the beginning, it looks to be 10' of run or so to the final turn from horizontal to vertical, so you'd be at center line 4" below the joists by then.

3) You could in theory do it without the Fernco coupling, by building the DWV starting at the existing CI. But there's no reason to make it hard on yourself, the Fernco coupling will probably be some useful flexibility. The type of coupling required depends on whether it is above or below grade: above grade is a ~2" long coupling with a shield; below grade is an ~4" long coupling with or without a shield.

4) If you have a vanity, you can still put most of the piping in the wall if you want, and just kick out of the wall with a 45 into the vanity toe kick space to avoid the double joist, entering the floor system at a 45.

5) For horizontal to vertical either medium or long turn quarter bends are allowed. When you have the space for either, not sure if there is a reason to prefer one or the other.

6) Both vents can be 1-1/2". I don't see anything about your layout that would give rise to specific concerns about your kitchen sink.

No washing machine standpipe?

Cheers, Wayne
 

Rich_Davison

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Thanks for the feedback. My daughter just got the house a couple months ago and the cleanup has occupied us primarily. I found the dish washer standpipe. It is a piece of PVC coming out of the concrete floor in the "cellar/basement". All I can tell is that there is a newer color concrete trail leading to the area of the main drain. No evidence of a trap and definitely no vent. I attached a sketch. This will have to wait for the primary bath work to get done and it may only need to be sealed off if she doesn't need it.
The only thing I can think that would prepare for adding the standpipe would be providing for a future vent into the basement while a wall is open.

Thanks again for the help. Richard
 

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wwhitney

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wwhitney

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washer standpipe. It is a piece of PVC coming out of the concrete floor in the "cellar/basement". All I can tell is that there is a newer color concrete trail leading to the area of the main drain. No evidence of a trap and definitely no vent.
IPC allows AAVs, so if the drainage side under the concrete is correct, and it's in the place you'd like, it's easy to make use of. Just put a san-tee on it at the correct height, and then an AAV on top. The side gets the usual 2" trap and standpipe. If you want to avoid an AAV, your idea of including a vent rough-in to the basement is foresightful.

Cheers, Wayne
 

Jeff H Young

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I double checked, and where the wet vent is draining only 1 DFU, then 1-1/2" is allowed. Go to 2 DFUs (double lav), and it needs to be 2". And unlike the UPC, the IPC allows a 1-1/2" vent for a 3" WC drain.

https://up.codes/viewer/michigan/mi-plumbing-code-2015/chapter/9/vents#912.3

Cheers, Wayne
Wayne isn't there a discharge of 3 fu into the wet vent? I'm seeing only 1 fu allowed? needing a 2 inch vent (912.3). I think the dry vent size is governed by discharge of fixtures into the wet vent
 

wwhitney

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I believe that's on a per section basis, there's no language saying the whole wet vent has to be the same size, like there is for circuit venting.

https://up.codes/viewer/michigan/mi-plumbing-code-2015/chapter/9/vents#914.3

So the section from the lav to the shower can be 1.5" (1 DFU), and the section from the shower to the WC can be 2" (3 DFUs). But the OP has a cleanout, at the end of the 3" run, so that's why I just suggested that up to that point it could be 1.5".

Cheers, Wayne
 

Jeff H Young

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I believe that's on a per section basis, there's no language saying the whole wet vent has to be the same size, like there is for circuit venting.

https://up.codes/viewer/michigan/mi-plumbing-code-2015/chapter/9/vents#914.3

So the section from the lav to the shower can be 1.5" (1 DFU), and the section from the shower to the WC can be 2" (3 DFUs). But the OP has a cleanout, at the end of the 3" run, so that's why I just suggested that up to that point it could be 1.5".

Cheers, Wayne
I thought the entire wet vent had to be sized for 3 fu and the dry vent needed to be the same size as that. but its not that easy to interpret . I'm just reading the 912.3 table at the top
 

wwhitney

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Well, if you contrast the language in 914.3 to the language in 912.3, the former makes it very clear that in a circuit vent, the entire circuit vent has to be the same size. Since that language is missing in 912.3, I take it to mean that a wet vent doesn't have that restriction, and that it can get progressively larger as more fixtures join it.

Cheers, Wayne
 

Jeff H Young

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Well, if you contrast the language in 914.3 to the language in 912.3, the former makes it very clear that in a circuit vent, the entire circuit vent has to be the same size. Since that language is missing in 912.3, I take it to mean that a wet vent doesn't have that restriction, and that it can get progressively larger as more fixtures join it.

Cheers, Wayne
Thanks Wayne I've read it(912.3) several times and I think your right on the dry vent . the wet vent I think needs be 2 inch in this case . If it was only a lav 1 1/2 wet vent would probably be good
 

wwhitney

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There's no question that after the shower hits the wet vent, the wet vent has to be a 2" minimum size, because it's a wet vent carrying 3 DFU of drainage. [If there were no wet venting, the IPC allows both the shower drain and the combined shower/lav branch to be 1-1/2". 3 DFU is the maximum allowed on a 1-1/2" horizontal branch under the IPC. This assumes the showerheads total less than 5.7 gpm.]

The question is whether that applies upstream of the shower/lav joint, where the wet vent is carrying only 1 DFU of drainage. While 912.3 by itself seems to be unclear on the topic, 914.3 on circuit vents has the notable language "The entire length of the vent section of the horizontal branch drain shall be sized for the total drainage discharge to the branch." The absence of that language in 912.3 on wet vents means to me that you can size the wet vent by section, it doesn't all have to be the same size, like it would with circuit venting.

[Sorry to repeat myself, but it's important to look at 914.3, not just 912.3.]

Cheers, Wayne
 

Jeff H Young

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There's no question that after the shower hits the wet vent, the wet vent has to be a 2" minimum size, because it's a wet vent carrying 3 DFU of drainage. [If there were no wet venting, the IPC allows both the shower drain and the combined shower/lav branch to be 1-1/2". 3 DFU is the maximum allowed on a 1-1/2" horizontal branch under the IPC. This assumes the showerheads total less than 5.7 gpm.]

The question is whether that applies upstream of the shower/lav joint, where the wet vent is carrying only 1 DFU of drainage. While 912.3 by itself seems to be unclear on the topic, 914.3 on circuit vents has the notable language "The entire length of the vent section of the horizontal branch drain shall be sized for the total drainage discharge to the branch." The absence of that language in 912.3 on wet vents means to me that you can size the wet vent by section, it doesn't all have to be the same size, like it would with circuit venting.

[Sorry to repeat myself, but it's important to look at 914.3, not just 912.3.]

Cheers, Wayne
Absolutly I follow you Wayne. its just that strong language on one code dosent change the words of another but it does cast some question .
 

wwhitney

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When the the two pieces of language are just two section away from each other, obviously I think it does. 914.3 shows you how the code writers put it when they want the whole thing the same size. And they didn't do that in 912.3.

Cheers, Wayne
 
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