Vent move for DIY bathroom

[ChrisNorthNJ]

First off - what a great forum this is, I'm lucky to have found it.

I imagine this is an easy question for some, but as I'm a DIY homeowner I want to make sure I get some advice. We're renovating a small square bathroom with a small walk in shower. There was a wall separating the side of the shower (where there was a fiberglass insert) and when I took it apart I learned there is a 1.5" vent pipe in that wall running up to the attic. The shower drain was running under that wall to meet up with the toilet drain then ultimately into a 3" pipe in the real wall. That vent pipe comes right off the drain line as it passes under that wall, so it's vertical all the way to the ceiling. I need to move the vent pipe into a real wall so that I can go with glass on 2 sides of the shower, but not sure the right way to route it. Can I go horizontal perpendicular to the drain line just to get the vent into a wall? Or do I need to reroute the drain line so that the vent can attach vertically to the drain line?

Thanks in advance!

 

[wwhitney]

New Jersey I understand follows the NSPC, so see section 12.6.2 and subsections here:

http://epubs.iapmo.org/NSPC/2018/mobile/index.html#p=192

Looks like if the current drain is low enough in the floor system, you could put a wye in rolled up 45 degrees, followed by a 60 degree bend to go horizontal perpendicular to the drain (assuming that's the right direction), then go to the wall you want and turn up with a long turn 90, then rise above the shower flood rim level, and then provide a cleanout.

If the above configuration would stick out of the floor, or if the cleanout is a problem, your best bet is to reroute the drain so it passes under a wall within the requisite distance from the shower trap. Which is also a better solution, in case rerouting is just as easy as the alternative procedure.

Cheers, Wayne

 

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[ChrisNorthNJ]

New Jersey I understand follows the NSPC, so see section 12.6.2 and subsections here:

http://epubs.iapmo.org/NSPC/2018/mobile/index.html#p=192

Looks like if the current drain is low enough in the floor system, you could put a wye in rolled up 45 degrees, followed by a 60 degree bend to go horizontal perpendicular to the drain (assuming that's the right direction), then go to the wall you want and turn up with a long turn 90, then rise above the shower flood rim level, and then provide a cleanout.

If the above configuration would stick out of the floor, or if the cleanout is a problem, your best bet is to reroute the drain so it passes under a wall within the requisite distance from the shower trap. Which is also a better solution, in case rerouting is just as easy as the alternative procedure.

Cheers, Wayne

Thanks Wayne! It looks like the drain line is pretty close to the subfloor already so I might not have room. Knowing that I have to eventually get back to the toilet to meet with the drain, would your second option mean it's ok to route the drain toward the open wall instead of straight at the toilet, do my venting from within that wall, then make another turn back out of the wall under the floor in front of the toilet so it can meet back up with the line where I cut it? Hopefully this pic helps.

 

[wwhitney]

I'm not sure what the typical solution is for your situation.

You could jog the drain close enough to the wall to bring a vent into it (using a combo, possibly rolled up 45 degrees instead of vertical). That would seem OK if you could do it with (3) 45s (plus the choice of p-trap outlet orientation), although drilling joists at a 45 is some trouble, but using (3) long turn 90s seems like a poor solution.

If you're willing to have a short knee wall, say 12" taller than your curb, then you could leave your vent where it is, let it rise 6" above the curb, then turn horizontal to head into the wall.

You could combine that idea with the option from my first post. That way instead of a knee wall, you could just have a curb on all sides, with the curb covering the area where the vent has to rise above the subfloor.

Maybe you'll get some other suggestions.

Cheers, Wayne

 

[ChrisNorthNJ]

I'm not sure what the typical solution is for your situation.

You could jog the drain close enough to the wall to bring a vent into it (using a combo, possibly rolled up 45 degrees instead of vertical). That would seem OK if you could do it with (3) 45s (plus the choice of p-trap outlet orientation), although drilling joists at a 45 is some trouble, but using (3) long turn 90s seems like a poor solution.

If you're willing to have a short knee wall, say 12" taller than your curb, then you could leave your vent where it is, let it rise 6" above the curb, then turn horizontal to head into the wall.

You could combine that idea with the option from my first post. That way instead of a knee wall, you could just have a curb on all sides, with the curb covering the area where the vent has to rise above the subfloor.

Maybe you'll get some other suggestions.

Cheers, Wayne

Wayne - that's genius - who says the curb can't be hollow? I think I'm going to use Wedi anyway, so I can just as easily frame it up to house the pipe and cover it with wedi board instead of using their pre-fab curb. Plus I need to anchor the glass wall anyway, and I might need a framed curb for that instead of just the foam. I'm going to open up more of the floor this weekend so we'll see how much room we have below the subfloor. Thanks!

 

[wwhitney]

You'll still need a cleanout if the vent goes horizontal in the curb. So it would need to run to the wall, jog left in the wall with 45s, and then have a cleanout (so that the cleanout is not where the glass hits the wall).

Also, the shower glass needs to be anchored to the curb(s) without penetrating the horizontal water proofing. That's best done with no holes at all, just silicone and wall brackets. In theory on a 3/8" thick tile a 1/4" deep hole would be OK, but in general you can't trust glass installers to only drill 1/4" deep.

If they do penetrate the horizontal waterproofing, it will leak, and your framing will get wet, and the shower and curb will need to be rebuilt.

Cheers, Wayne

 

[ChrisNorthNJ]

That's perfect. There's a closet on the other side of that wall so I can actually just hide an access panel low in the closet and face the cleanout toward that side, then I probably don't even need to jog left. Hopefully this is as straightforward as it sounds.

 

[ChrisNorthNJ]

The plot thicken! Or should I say, turns... I opened up the floor today and to my surprise, instead of joining the toilet and sharing a drain, it looks like the shower drain line makes a turn toward the rear of the house and meets up with the stack via another route. I was happy when I saw this, but hope my happiness is well justified. I'm hoping I can replace the 90 degree turn between the joists with a santee and extend the "uphill" part toward the back wall, make the turn to vertical, add a cleanout tee then go straight to the attic inside that wall. (green arrows are proposed vent path, existing tee would be removed under the red X and p trap would be replaced with a longer one. I can also cheat the drain over a little to the left if that's too long for the p trap to go before the vent, but it's a 2" drain so I might be ok) Am I good with this?

 

[wwhitney]

No.

The only kind of vent that can be attached on the horizontal is a horizontal wet vent. A horizontal vent attachment could provide a "cul-de-sac" for solids to gather. With a horizontal wet vent, the other fixture draining through the wet vent would wash that down. But if it's a dry vent, like you have, there would be nothing to keep the solids from accumulating.

So you can't attach a dry vent on the horizontal, it has to be taken off on the vertical (or at most 45 degrees from vertical). Stick with the previous plan.

Cheers,
Wayne

P.S. If you had more fall available to you (if the pipe going towards the bottom of the picture under the plywood were lower), you could do the following:

Flip the p-trap u-bend around 180 degrees, and point the p-trap outlet to the top left in the picture (45 degrees to the wall where you want the vent). Under the wall, put in a street 45 leading to a vertical combo for the vent takeoff. Then depending on where you end up left/right, either a long turn 90 to line up with the drain, or two 45s with a pipe segment in between. Flipping the u-bend is so that the combo outlet doesn't end up too far to the left.

But this would add~3' of run to the shower drain, so you'd need to have another ~3/4" of drop. Since the drain going under the plywood is fixed in height, you'd have to raise your p-trap 3/4". Which looks like it would make it too high.

 

[ChrisNorthNJ]

Hmm... I see. I think I can squeeze another 3/4" of drop - the far right of where the shower needs to be is an exterior wall, and being an old house there's a bit of slope from there, so I'm going to need to shim the joists up a bit anyway to create a level subfloor for the shower pan, which could easily net a quarter inch or so. There's currently 2 subfloors and 2 layers of tile in there so even if I added a whole 3/4" I'm still ahead of the game. My one other thought - how do you feel about notching those joists? One already is notched where the tee with the current vent is. Since I'll still be near the top, I'll probably have to notch the cut joist and the cross-member to make that 45 run to the back wall. That still ok?

 

[wwhitney]

The joist question is an important one, answering it would require more information. E.g. the joist height, which way the joists run (looks like up and down in the picture, with one joist headed off for the shower drain), and how far it is in each direction to the supports. And is the shower drain moving at all?

So avoiding that analysis is a good reason to stick with the shower curb plan. You could also take a look in the joist bay to see where the drain pipe goes--if it happen to turn down before meeting any other drains, you could lower the shower drain.

Cheers, Wayne

 

[ChrisNorthNJ]

Makes sense. Like all things, I guess this turned into a bigger project than I planned it to be. Thanks for all the help.

 

[ChrisNorthNJ]

After a bunch more investigation, looks like the curb idea is a winner. I'll replace the current wye with a new one, but rolled 45 degrees toward the back wall, then a 60 degree turn to make the horizontal offset into the wall. I'll frame it up with plywood around the pipe for strength since it's all going to be covered by a wedi curb-over, then tile. The cleanout will face the rear and be accessible from a panel on the other side of the wall. That'll give me a 45 degree vent takeoff, and a little slope in the offset, good enough for 12.6.2 in the NSPC if I'm reading this right. Now I just have to pray the curb is tall enough to house it. Thanks Wayne, you may have kept this project in the realm of DIY for me.

 

[ChrisNorthNJ]

PVC work done. This look ok?

 

[wwhitney]

My interpretation of NSPC 12.6.2.2 is that it would preclude the use of a sanitary tee for the vent takeoff. A sanitary tee on its back is not a drainage pattern, so for a tee I would think a combo tee-wye is required.

Also, since you used a tee with a 60 degree bend to go horizontal, you must have rolled up your tee 60 degrees. The utility of a 60 degree elbow is when you have a wye rolled up 45 degrees; then the 60 degree elbow lets you immediately go to horizontal while making a 90 in plan view. [You could use a 45 to make the wye into a combo tee-wye, and another 45 to go horizontal; that would be fine, but the two 45s are not in the same plane, so they are rotated relative to each other, and they end up making a net bend of just 60 degrees. Also, the 60 would be more compact and give you less total rise, making it easier to fit in your curb.]

Lastly, if the cleanout is to be accessed from the closet, shouldn't it be turned 90 degrees to face the closet?

Cheers, Wayne

 

[ChrisNorthNJ]

The cleanout is a little too close to the wall so I had to face it sideways, but the access panel will be big enough where I can fit my whole hand in there to open it up. As for the santee, I went with that because too much of the wye stuck out of the floor where I would need to be building the curb. There was just a straight tee there before, so hopefully this is adequate. When I took apart the original vent there was no debris and very little sign of any prior moisture.

 

[wwhitney]

The cleanout is a little too close to the wall so I had to face it sideways, but the access panel will be big enough where I can fit my whole hand in there to open it up.

I think a more typical solution would be to simply cut a hole in the drywall for the hub of the cleanout and let it stick through. No access panel required.

I don't have the experience to know if the access you intend would really be sufficient to properly get a snake in there. Certainly an access panel should be off center to provide more access on the cleanout side. Turning the cleanout 45 degrees at least would also help.

As for the santee, I went with that because too much of the wye stuck out of the floor where I would need to be building the curb.

A wye and a 60 should only give you a net rise of about 3". Or perhaps you mean horizontally, perpendicular to the curb? If you were under the UPC, it would be clear that you need a wye, and you'd just have to make the curb framing work around it. For the NSPC, the language is a little less clear.

Cheers, Wayne

 

[ChrisNorthNJ]

Understood. Being that this is a true homeowner DIY situation though and the only standard I'm really being held to are the laws of physics, should this be functionally ok despite being questionable code-wise? I feel like gravity and conditions are all working in my favor even if it's not the ideal fitting.

 

[wwhitney]

Answering that question requires more experience than I have.

I will say that code requirements are generally there for a functional reason. However, it may be to cover a 1% case/occurrence. So you could take a gamble that you're not likely to see that case, and your solution would be sufficiently functional.

What's the problem with the wye? Would it really project beyond the envelope of the desired curb framing, and how much? If it just intersects some of your curb framing without projecting beyond it, I'm sure you could frame a sturdy curb with the interruption.

Cheers, Wayne

 

[ChrisNorthNJ]

The problem with the wye wasn't the height, but the width of the angled part of the wye plus the 60 making it's turn was wider than I have clearance for within even the widest curb option. With a 5" exterior width curb made of 3/4 foam, framing it with 3/4" plywood (plytanium if I can get it) leaves me a 2" wide cavity to sneak the pipe though, and even at that I'll need to route it a little for the socket ends of the two fittings. The angle of the wye just made the whole assembly too wide. It also would've needed to start further left in the picture so that the vent pipe lands in the curb, which would've forced me to put pressure on the existing drain pipe so that the elbow would open up further left. It was tricky - I spent a while with a box of fittings trying out different options, but this was the best thing I could come up with.