Toilet venting

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Tommy Dee

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Venting question:
Can I use a santee to vent from a horizontal 3 in waste line for a toilet. See picture I attached. I plan on using the santee and a 90 to connect the drain to the existing Vertical vent line. is this ok or should I use a longer sweep?
Thanks
 

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wwhitney

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The IPC arguably allows a san-tee on its back for a vertical vent takeoff from a horizontal drain line. It also prohibits the vent from going horizontal or combining with another vent until an elevation 6" above the flood rim of the fixture.

So if you are connecting to that copper DWV there, presumably it is dedicated to the WC. In which case you would roll your san-tee to 45 degrees off vertical (no more) and then use a 45 to turn up vertically into the wall. And move the 3" WC fixture drain a little closer to the wall if necessary to keep that 45 degree leg from interfering with your floor finish.

If that copper is a vent for a lower fixture, you need to move the vent takeoff left or right, rise into the wall as above but parallel to the copper, and then join the copper DWV with a wye/san-tee higher up.

Cheers, Wayne
 

Tommy Dee

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Is this ok? Turning the San-tee on a slight angle and using a 45 and 22.5 to connect to the existing copper vent. See pic. Will need to go through a floor joist tho...
 

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wwhitney

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No, after those bends you're more than 45 degrees from vertical, so that's considered horizontal. Can't you roll the san-tee 45 degrees from vertical and pass under the bottom of the joist to hit a 45 to turn up into the wall?

Cheers, Wayne
 

Tommy Dee

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No, wasn’t able to connect that way. maybe I’ll try it with a wye- can I do the same with the wye? Roll it 45 degrees and use the 45 to turn up into the wall?
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wwhitney

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I'm a little surprised based on the photo, but I guess you hit the bottom of the joist more than would be reasonable to notch it? (E.g. a diagonal partial notch (edit: I mean bevel) 1" in width by 1" in height would be fine.)

You can try the wye, but you'd need a 60 degree bend to go from the branch on a wye rolled 45 degrees to vertical. Which of course means that the wye branch isn't actually "vertical", but I guess that's commonly overlooked when the pipe segment between the wye and the 60 is very short. Which would also mean that you could roll your san-tee 60 degrees and just use a 60 degree bend, and that shouldn't be any worse. Although somehow it would seem worse.

One more option you have: if I recall, after this vent the 3" line is hitting a 90 to turn downward. If that's correct, you could do the following, starting at that 90 and going upstream: turn the 90 22.5 degrees towards the wall, then hit a horizontal 22.5 degree bend (possibly street). Then your san-tee vent take off, which is now closer to the wall, so rolling it 45 degrees should let you get under the wall. Then upstream of that you hit a pair of 22.5 degree bends to jog back to the original course of the 3" line. Or if upstream is just a closet bend and a closet flange, you just use one 22.5 and rotate your closet bend 22.5.

Cheers, Wayne
 
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Tommy Dee

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Thanks so much, I’ll see which of those work tonight. I can probably notch it a drop also, just was under the impression a bottom notch isn’t the greatest. not so sure how they got away with it originally when it was done- that vent was connected on its side with a santee
 

frodo

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Thanks so much, I’ll see which of those work tonight. I can probably notch it a drop also, just was under the impression a bottom notch isn’t the greatest. not so sure how they got away with it originally when it was done- that vent was connected on its side with a santee

A bottom notch is BAD JU JU. But can be done if you head the joist off

ajuy.jpg
 

Reach4

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Any chance you could add the drainage from a lavatory? Horizontal wet venting is OK.
 

wwhitney

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A bottom notch is BAD JU JU.
The building code doesn't differentiate between top and bottom notches. It does prohibit them in the middle third of the span, which I should have mentioned.

https://up.codes/viewer/new_york/irc-2018/chapter/5/floors#R502.8

I'm a little unclear on whether there is a structural engineering reason that a notch on the tension side of a wood bending member would be worse than a notch on the compression side.

And to be clear, "diagonal partial notch" is a poor description of what I meant, which is to bevel one corner of the joist for a few inches in length. I.e. a 1" x 1" bevel on a 1-1/2" thick member would mean that 1/2" of the 1-1/2" thickness would still be full height. A 1" bevel is the point at which I'd start thinking about rerouting the horizontal drain with some 22-1/2 bends instead of beveling; and I wouldn't bevel much more that than without considering it a full thickness notch.

Cheers, Wayne
 

frodo

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A HOLE in the cnter of the beam still maintains the strength of the beam depending on the size and lateral location of the hole.
a notch, on top or the bottom reduces the load bearing of that beam.
let say you notch a 2x12 with a 2'' notch on the bottom. The beam is now a 2x10 load bearing beam, The span distance has changed and that is a weak spot.

where as a 2'' hole centered will not change the load bearing
I am not an engineer, I have been told by an engineer this info.
 

Tommy Dee

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Right so originally I would’ve made hole In the center, but it’s a problem with the vent being horizontal
 

Reach4

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Unfortunately no- nothing close enough to make it worthwhile
You could add a small one.

Right so originally I would’ve made hole In the center, but it’s a problem with the vent being horizontal
How big is your joist?
Any chance of making that hole at 45 degrees? I don't know how you would pull off drilling that hole. Might be totally impractical.

2 inch copper is 2.125, so probably a 2.25 diameter inch hole. With PVC, the hole would be bigger.

You might make a sketch of a side view where the 3 inch pipe shows as a circle, and the joist shows as a rectangle.
 

frodo

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to cut a 45 degree hole
cut a 4x4 on a 45. screw it to the board
drill your hole. centered on the 45 /4x4 when the worm on the bit passes from the 4x4 to the joist. remove the 4x4
and drill that joist. go slow at the exit. it tends to be a wild ride
 

wwhitney

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The IPC would allow a 1-1/2" vent. If you are under the UPC for some reason, then 2" is required.

Cheers, Wayne
 

Tommy Dee

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So maybe I’ll use a 1.5 in to the drain and connect to to the 2 in copper vent. Might clear the joist that way
 
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