Adding Shower to existing toilet drain

[wwhitney]

So a dry vent takeoff has to be vertical (at most 45 degrees off plumb) and stay vertical until at least 6" above the flood rim. You'd take off the dry vent directly into the wall, and if you need to move the dry vent across to the other side of the window, do that in the wall at least 6" above the shower flood rim (the curb).

Also, unfortunately, while a shower only requires a 1-1/2" vent, a WC requires a 2" vent, and since you'd be tying the shower drain into the WC before the WC hits the stack, the shower drain has to wet vent the WC, rather than relying on the stack to dry vent the WC. In which case the dry vent on the shower needs to be 2", not 1-1/2".

But if the stack you are tying into has no drainage from above (or if the only drainage is a lav from this bathroom), then how about using a san-tee with side entry, a 3x3x3x2? That would let you tie the shower and the WC into the stack at the same elevation, so it should allow both drain lines to fit within the floor system. And then the stack can vent both fixtures. [Tying them in with shower directly above the WC would also work venting-wise, but take up more height, so probably wouldn't fit.]

If the stack you are tying into has drainage from a story above, or from a non-bathroom fixture above these fixtures, then it can't be used as a vent at all. In which case dry venting the shower and using it to wet vent the WC is the way to go.

Cheers, Wayne

 

[Jeff H Young]

latest drawing with what apears to be a 1 1/2 dry vent below the floor cant be dry or 1 1/2 if serving the w/c needs 2 inch

 

[Sponsor]

 

[DeRanger]

Guys's,
I swear I am not trying argue. I appreciate your patience as I present the challenges I see with your recommendations. I assure you I am thankful for your expertise and I am only pressing for solutions.

In which case the dry vent on the shower needs to be 2", not 1-1/2".

I wonder if that is a California requirement. King County states the following:

"Note: The diameter of an individual vent must not be less than 1-1/4 inches nor less than 1/2 the diameter of the drain to which it is connected." (https://kingcounty.gov/so-so/dept/d...llations/drainage-venting-fixture-unit-values). If the WC is 3" wouldn't that be 1-1/2" vent?

and if you need to move the dry vent across to the other side of the window,

Two hesitations with this 1.) It seems like there has to be an easier way to tie the vent into the 3" stack that would be within 14" poking out the roof. I already have two abandoned vent pipes extending through the roof within 10'. 2.) I am swapping and moving the 36" window to the left, 12" from the wall with the vent stack (the window is to scale on the drawing provided.). That means that a king stud, a jack stud and now I have 8" to try and pull the vent back behind where the p-trap drain opening is going.

If the stack you are tying into has drainage from a story above, or from a non-bathroom fixture above these fixtures, then it can't be used as a vent at all. In which case dry venting the shower and using it to wet vent the WC is the way to go.

This is the top floor, the 3" vent stack is straight through roof.

But if the stack you are tying into has no drainage from above (or if the only drainage is a lav from this bathroom), then how about using a san-tee with side entry, a 3x3x3x2? That would let you tie the shower and the WC into the stack at the same elevation, so it should allow both drain lines to fit within the floor system. And then the stack can vent both fixtures.

I like this idea! The challenge is that I have about 2" between the floor joist and the wall. Cutting out the 3x3x3 sani-tee without destroying the 3' pipe below it would be the caution. I might have to figure out how to make this happen if you have no other recommendations?

 

[DeRanger]

latest drawing with what apears to be a 1 1/2 dry vent below the floor cant be dry or 1 1/2 if serving the w/c needs 2 inch

As mentioned, King County states "Note: The diameter of an individual vent must not be less than 1-1/4 inches nor less than 1/2 the diameter of the drain to which it is connected." (https://kingcounty.gov/so-so/dept/d...llations/drainage-venting-fixture-unit-values).

If the WC drain is 3" I can go to 1-1/2", yes?

 

[wwhitney]

I wonder if that is a California requirement. King County states the following:

Nope, see UPC Table 703.2 footnote 3, which is appended to the 1-1/2" vent entry of the table, and means a 1-1/2" vent can't be used for a WC.

Chapter 7 Sanitary Drainage: Sanitary Drainage, Washington Plumbing Code 2021 | UpCodes

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Cheers, Wayne

 

[DeRanger]

Ok, how about this. A 3x3x2x2 Sani-wye. 2nd 2" comes off and goes up wall and then runs increasing horizontal to tie in with 3" vent stack?

I am attaching pictures from previous version only so you can see the tight run from the shower p-trap and what moving the window would look like. Also so you can see the limited space I have to cut out the 3x3x3 sani-tee behind the double joists.

 

[wwhitney]

Ok, how about this. A 3x3x2x2 Sani-wye. 2nd 2" comes off and goes up wall and then runs increasing horizontal to tie in with 3" vent stack?

No, a dry vent takeoff may not be on the horizontal, it needs to be on the vertical and come off the upper half of the cross-section. Also, the 3x3x2x2 fitting you show is called a double wye and isn't to be used on the horizontal like that. [Well, it's possible but tricky with some extra considerations I don't want to get into now.]

Where is the lav drain going to be? Can you reroute it, upsize it and its vent to 2", and use it to wet vent the shower and the WC? In WA state, the WC is not required to be last on a wet vent (an amendment to the UPC), so you could make your original WC/shower geometry work from post #14 simply by joining the 2" dry vented 2" lav drain to the WC before the shower joins it.

Lastly, you could pull a 2" dry vent off the shower directly under the wall and rise up to the left of the window if you can get around the corner higher up in the wall or in the ceiling framing or attic to reconnect to 3" stack.

Cheers, Wayne

 

[DeRanger]

No, a dry vent takeoff may not be on the horizontal, it needs to be on the vertical and come off the upper half of the cross-section. Also, the 3x3x2x2 fitting you show is called a double wye and isn't to be used on the horizontal like that. [Well, it's possible but tricky with some extra considerations I don't want to get into now.]

Where is the lav drain going to be? Can you reroute it, upsize it and its vent to 2", and use it to wet vent the shower and the WC? In WA state, the WC is not required to be last on a wet vent (an amendment to the UPC), so you could make your original WC/shower geometry work from post #14 simply by joining the 2" dry vented 2" lav drain to the WC before the shower joins it.

Again, the Lav drain takes it completely separate route and completely away from this corner of the bathroom. If you think this situation is tricky, the Lav drain would be impossible.

I am aware that a dry vent takeoff can not be on the horizontal. I am looking to use this as a wet vent application.

Also, the 3x3x2x2 fitting you show is called a double wye and isn't to be used on the horizontal like that....

...In WA state, the WC is not required to be last on a wet vent (an amendment to the UPC), so you could make your original WC/shower geometry work from post #14 simply by joining the 2" dry vented 2" lav drain to the WC before the shower joins it.

I cant get the youtube video link to work but the title is "Toilet And Shower Wet Venting For Plumbing Drain Pipes In Floor Framing - Project #1" and posted by homebuildingandrepairs
Take a look at minute mark 2:27 of this video. I don't have a lav as is shown in the video, but if I can take the vent off the double wye (thank you for correcting me) and tie it in with the stack 4 feet up, wouldn't that be the same application as the video and what you are suggesting above?

 

[wwhitney]

I am aware that a dry vent takeoff can not be on the horizontal. I am looking to use this as a wet vent application.

A wet vent is a drain that also acts as a vent. So without another dry-vented fixture draining in, you can't have a wet vent. That's why I mentioned the lav, it could be the dry-vented fixture whose drain acts as a wet vent.

I don't have a lav as is shown in the video,

And therefore you can't do a wet vent as shown in the video. [I didn't watch the video.]

Cheers, Wayne

 

[Tuttles Revenge]

Is there a lavatory sink in this bathroom? Is it just on the opposite side of the toilet from the shower? If you used that fixture as your dry vent, and connected it to the existing toilet stack you could complete your HWV system. You would need to upsize the existing sinks vent to 2" in order to accommodate the toilet.

*edit*
just read the "impossible" word for the sink.. nothing is impossible.. difficult maybe.

 

[DeRanger]

Guys,
About the Lav drain.

just read the "impossible" word for the sink.. nothing is impossible.. difficult maybe.

The double Lav joins together 7 feet to the left of this pic and drops down under this wall and runs horizontal under that visible wall, sandwiched between the hot and cold 1/2" copper lines (hot on the front side and cold on the back side, I swear...Weirdest thing I have ever seen). It goes to the right and drops down 6 inches before the drain stack, and it drops down right on top of the wall directly below the wall that is visible in this picture. Literally sitting on the top plate of the lower floor wall. Meaning..., the grade is BELOW the 3" WC trap by about 3 inches. The Lav vent does rise at the double sani-tee and above 42" and runs to the right and ties in with the vent stack. That is where I think I could tie the vent in at the 3x3x2x2 double wye in the last version.

This is all underneath the visible wall. There are double floor joists running parallel to the walls within 2 inches. The floor below this is a kitchen with hanging cabinets. There is no way to cut into the ceiling and reach any of the drain or water lines without tearing the kitchen out. Hence, I say it is IMPOSSIBLE. If someone can explain how to make that just a difficult task, I am all ears.

 

[wwhitney]

If someone can explain how to make that just a difficult task, I am all ears.

So assuming it is OK to drill the double joist (would not be any worse than that 3" line going through it, I would just suggest confirming the joist is doubled because of that penetration and not doubled for some other reason, with some other reinforcement made for the hole for the 3" line):

You've already removed some of the bottom plate of the wall in a couple of your photos. That should let you access the existing lav line to cut it off and cap it.

At your lav san-tee location, remove the bottom plate as required for access. Drill a 2-1/2" hole through the double joist within the limits of 2" clear from each edge and at the correct elevation to meet up with the rest of the bathroom plumbing. Bring a 2" lav drain down through the bottom plate to a LT90 that turns it through your hole in the double joist, to a LT90 that turns the drain to run parallel to the joist. Have the 2" lav drain hit a 3x3x2 or 3x2x3 wye to join the WC drain and wet vent it, then the combined drain hits a similar wye to receive the shower drain and wet vent it. Then the 3" drain connects to the existing 3" san-tee in your stack. The geometry near the stack can be the mock up in the photo in your first post.

The lav san-tee is 2x2x1-1/2 and gets a 2" dry vent that has to rise up in the wall and connect to the stack at least 6" above the lav flood rim. That could be in the attic, in the ceiling framing, or in the wall itself. If you have to drill 2-1/2" holes in 2x4 studs, that's perfectly fine in a non-bearing wall if you use HSS2-SDS1.5 stud shoes. Possibly OK in a bearing wall as well, but I'd want to know more about what it bears.

Cheers, Wayne

 

[wwhitney]

So I think you've got 3 viable solutions, you can figure out which is the least trouble for you:

1) replace the 3" san-tee on the stack with a 3x3x3x2 san-tee with sanitary side entry, bring the shower drain to that side entry (requires drilling the double joist for the 2" shower drain)
2) pull a 2" dry vent off the shower drain so it can wet vent the WC; the 2" dry vent rises to the left of the window and then needs to reconnect to the stack (somewhat annoying as that wall is an exterior wall).
3) redo the lav drain and vent as in the previous post (requires drilling the double joist for the 2" lav drain)

Cheers, Wayne

 

[DeRanger]

I would just suggest confirming the joist is doubled because of that penetration and not doubled for some other reason

I believe they are double up because of how the sub floor is laid out. The Sub floor are 2' x 8' sheets, with the ends staggered. I think it was done for nailing the ends of the sub floor. As I mentioned, this is top floor and the wall is parallel to joists and rafters. I am positive it's not load bearing.

and at the correct elevation to meet up with the rest of the bathroom plumbing.

This is the key to this option. Looking at an 1-3/4" rise to tie in with the rest of the bathroom plumbing. Maybe.

HSS2-SDS1.5 stud shoes

First time I have heard this. Thank you for the new learning!

I think you've got 3 viable solutions, you can figure out which is the least trouble for you:

Agreed, Thank you! I believe I can make one of these work.

 

[DeRanger]

So I think you've got 3 viable solutions, you can figure out which is the least trouble for you:

1) replace the 3" san-tee on the stack with a 3x3x3x2 san-tee with sanitary side entry, bring the shower drain to that side entry (requires drilling the double joist for the 2" shower drain)
...
3) redo the lav drain and vent as in the previous post (requires drilling the double joist for the 2" lav drain)

Cheers, Wayne

Well I decided to do a combination of #1 & #3. Completely redid the lav and vent with 2" (ignore the vertical length, I will cut that and add a cleanout when I get the 3" drain/vent in place. Because the existing 3x3x3 was sitting too high to get correct slope and also to get to that 1-1/2" previous lav drain, I cut the 3x3x3 out and re-ran the whole thing.

Before I glue this up. Just want to make sure I did it right, If you guys wouldn't mind?

 

[DeRanger]

Hello? Wayne, Tuttles Revenge, Bueller...?

 

[wwhitney]

Before I glue this up. Just want to make sure I did it right, If you guys wouldn't mind?

The arrangement is compliant with the UPC.

Function-wise, it would be nice to avoid the two LT90s on the shower trap arm and avoid drilling that joist twice. The 3x3x2 wye for the shower could be a street fitting directly into the 3" san-tee on the stack, and then maybe you could avoid one LT90 by turning the trap outlet? Or at least change one LT90 to a 45 by turning the trap outlet?

Cheers, Wayne

 

[DeRanger]

The arrangement is compliant with the UPC.

Thank you for confirming!!.

3x3x2 wye for the shower could be a street fitting directly into the 3" san-tee on the stack,

I didn't try a street union (?) but I can. Just seemed like with the double joists right up against the 3x3x3 stack and trying to get my 1/4 turn with gluing, I didn't have enough bay space to fit the 3x3x2 with a 45, street 45, 90 or street 90. But I will give it a shot.

Mucho thanks!

 

[wwhitney]

I didn't try a street union (?)

I was suggesting a street 3x3x2 wye, a fitting whose outlet is a spigot instead of a hub, so it can go directly into the 3" santee. That would move the 2" inlet closer to the edge of the joist bay, maximizing the space you have for a (street) LT90 within the same joist bay. But that might move the wye too much towards the exterior wall so it wouldn't fit within the existing hole in the joist.

Cheers, Wayne