Bath reno existing plumbing not to code

[Renodread]

Hi all, I am in the middle of a bath renovation in Connecticut and have been diving deep into building code, but have some questions I was hoping you all could help me with. The attached image is more or less how the original 1978 plumbing was done (note that the ferncos are temporary to keep the upper bath running while this reno is being done)

https://imgur.com/37XfQdB

A is a 2x2x1-1/2 tee - my understanding is that a horizontal tee here is not to code and I should replace with a combination wye?

B is a 3x3x2 low heel elbow - this should be replaced with normal elbow and i should tie the upper shower in with a wye between B and C?

C is a 3x3x1/2 tee - this should be replaced with a combination wye?

Here is an updated image with my changes in mind. Thanks, I appreciate you all.

https://imgur.com/qql0HAn

 

[wwhitney]

A few comments:

- Yes, each of the fittings labeled A, B, C have the wrong curvature. They have the curvature of a quarter bend, and they should have the curvature of a LT90, as the outlet is horizontal. Meaning the san-tees should be replaced with combos. [In your proposed drawing, you show a horizontal wye at B. If it fits, you could change B to a combo on its back instead of using a horizontal wye.]

- If I understand your labeling correctly, the wet venting for the shower and WC in this bathroom are wrong. You have the 1-1/2" drain coming across the joists labeled "upper sink and bath". You can't use a drain from another floor as a wet vent, only drains from the bathroom group(s) on this floor.

- Why is the 1-1/2" stack on the right labeled "wet vent" above the san-tee? I assume that san-tee is for the lavatory connection, and the stack above it should be a dry vent, no drainage from the floor above. If it does carry drainage from the floor above, it can't function as a dry vent for this bathroom.

Cheers, Wayne

 

[Sponsor]

 

[Renodread]

In your proposed drawing, you show a horizontal wye at B. If it fits, you could change B to a combo on its back instead of using a horizontal wye.

Good call.

Why is the 1-1/2" stack on the right labeled "wet vent" above the san-tee? I assume that san-tee is for the lavatory connection, and the stack above it should be a dry vent, no drainage from the floor above. If it does carry drainage from the floor above, it can't function as a dry vent for this bathroom.

Just a misuse of the term.

If I understand your labeling correctly, the wet venting for the shower and WC in this bathroom are wrong. You have the 1-1/2" drain coming across the joists labeled "upper sink and bath". You can't use a drain from another floor as a wet vent, only drains from the bathroom group(s) on this floor.

Would adding the yellow vent solve the issue?

Thank you!

https://imgur.com/or1Ceko

 

[wwhitney]

Would adding the yellow vent solve the issue?

Partially, you'd also have to get rid of the connection called A in the OP and move it to downstream of where the shower joins the WC. That is required for this dry vented shower to wet vent the WC, no outside fixtures on the wet vent.

For the yellow dry vent, it would need to be vertical (at least 45 degrees above horizontal) until 6" above the shower flood rim. So you'd have to route the shower trap arm through an additional joist, and then take off the vent close enough to the wall that the yellow vent could enter into the footprint of the wall before it rises above the subfloor. And then route it back through the joist to hit the WC drain to wet vent it.

As an alternative to dry venting the shower, you could eliminate the connection called C in the OP, and instead bring the lav drain by itself into the floor system, and connect it to the shower trap arm. I.e. it would run to the left to get past the WC, then LT90 to go through the joist, then hit a combo to join the shower drain. That would let the lav wet vent both the shower and the WC.

In other words, you need to do both the first paragraph above, plus either the second or third paragraph.

Cheers, Wayne

 

[Renodread]

If I am understand your alternative correctly, something like this?

https://imgur.com/BEM8eb1

My only concern is clearance through the sole plate and past the 3"

 

[wwhitney]

If I am understand your alternative correctly, something like this?

Yes, that works, assuming you can maneuver the lav drain as it enters the floor system around the 3" line carrying the upstairs WC and shower. You could 45 the lav drain low to the sole plate so it protrudes into the backside of the wall board; or if there is a lav cabinet going to the floor, you could even have it protrude out of the wall into the cabinet toekick space. The sole plate is not really structural, so between studs you can notch it as much as necessary. Depending on where the next joist is, you might also be able to offset the 3" line away from the camera.

Also, you'd have to check that the fall works out: the highest the lav drain can be as it enters the floor system is with the top of the pipe up against the subfloor [which could be hard to achieve], and it has to fall at least 1/4" per foot as it traverses around, so that gives you a maximum height for the lav at the shower/lav drain connection. While if the shower trap isn't going to extend below the floor joists, that gives you a minimum height for the shower drain at that connection. I think if that works out, you wouldn't have any height issue at the WC/shower connection, but that should also be verified.

BTW, nice drawings on top of the photo, has made discussing this straightforward.

Cheers, Wayne

 

[Renodread]

Thanks. I think there is enough room to clear the 3" coming off the sole plate with a short turn 90. Let's assume the fall does not work out over that distance, would this layout work? Thanks again, I appreciate your time.

https://imgur.com/0XkuOvY

 

[wwhitney]

Thanks. I think there is enough room to clear the 3" coming off the sole plate with a short turn 90.

But when drainage turns to horizontal (from either horizontal or vertical), you need a long turn 90. When turning to vertical, you can use a quarter bend.

Let's assume the fall does not work out over that distance, would this layout work?

Two correctable issues with that:

(1) The lav needs to join either the WC or the shower (under the IPC, doesn't matter which order) before they jointly join the third fixture. So if it's a single layer (no crossings over) and the WC is closer to the wall than the shower in the joist bay, you'd join the lav to the WC, and the shower would join the WC downstream of that. Most compact would be 3x3x1-1/2 street wye for the lav entry directly into 3x3x2 wye for the shower entry.

(2) The shower trap arm needs to join the drain that is wet venting it within 2" of fall from the trap outlet. So the total run to that wye plus street 45 when the shower joins the now WC plus lav drain is at most 8', which you can get if you achieve the perfect minimum fall of 1/4" per foot.

Note that if (2) is close, you have the option to jog the lav drain towards the shower within the wall before it enters the floor. At least as far as you can without running into the 3" stack or the combo where it joins the 3" horizontal line.

Cheers, Wayne

 

[Renodread]

But when drainage turns to horizontal (from either horizontal or vertical), you need a long turn 90. When turning to vertical, you can use a quarter bend.

Got it - I think a long turn could still fit if I glue the joint within the sole plate.

(2) The shower trap arm needs to join the drain that is wet venting it within 2" of fall from the trap outlet. So the total run to that wye plus street 45 when the shower joins the now WC plus lav drain is at most 8', which you can get if you achieve the perfect minimum fall of 1/4" per foot.

The run from shower trap to wye entry would be about 6'. So based on my understanding of what you're saying, this diagram should be to code.

https://imgur.com/hUWTHov

 

[wwhitney]

Got it - I think a long turn could still fit if I glue the joint within the sole plate.

Another thing that may be useful would be to use two 45s or a 45 and a street 45. Just to give slightly different geometries.

The run from shower trap to wye entry would be about 6'. So based on my understanding of what you're saying, this diagram should be to code.

Yes, as long as the total drop from the 2" shower trap outlet to the crotch of the 3x3x2 wye where the shower joins the 3" line (which is the wet vent) is at most 2".

Cheers, Wayne

 

[Renodread]

Thanks

 

[Jeff H Young]

upstairs water closet dosent require vent or the wet vent connection dosent need to be on the same floor level as the fixture ?

 

[Renodread]

One last question - does the wet vent from the lav need to be 2" since it's venting a WC and shower?

 

[wwhitney]

One last question - does the wet vent from the lav need to be 2" since it's venting a WC and shower?

The size of a wet vent (any pipe that is both a drain for upstream fixtures and a vent for downstream fixtures) is the greater of the minimum size based on its role as a vent, and the minimum size based on the drainage it is carrying.

The IPC permits a 1-1/2" drain to be a wet vent if it is only carrying 1 DFU (e.g. one lavatory). And it permits a 1-1/2" vent for a WC plus a shower. So 1-1/2" suffices for the portion of the wet vent carrying only the lavatory.

Cheers, Wayne