Stumped (once again) on routing vents and boring joists

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wwhitney

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The wye doesn't have to be under the wall. It can be next to the wall plate (in projection on a floor plan), and rolled 45 degree off vertical pointing towards the wall. Then a 60 degree elbow will turn the pipe straight up into the wall. The longer the pipe between the 60 and the wye, the more the pipe will move towards the wall. But you are limited in how far the wye can be away from the wall, as you want the pipe to rise through the bottom plate of the wall, not through the subfloor outside of it. The height of the wye thus comes into play here, and the allowable range of heights will be limited by the need to reach the other end of the bathroom with 1/4" per foot fall, while staying within the height of the floor framing.

As for the trap, is the apparent double joist next to it the same as the joist to the left, i.e. a single joist plus a 2x4 nailer for leveling the future subfloor? If so, you can cut out the 2x4 nailer where it's in your way. An angled hole through the joist would be a fine thing to do. But you can turn the elbow outlet to be perpendicular to the joist if that gets you close enough to the wall. I don't think you have room in a single joist bay to both jog with a pair of 22.5 or 45 elbows and put in a wye, but you could jog in the joist bay next to the trap, and put your wye in the following joist bay. (Unless the long turn 90 has to be in that bay, and you don't have room. Although you could just continue the shower drain into the next joist bay, and have the shower drain join the tub drain, and wet vent it.)

BTW, your wye is backwards. It needs to be oriented so that if there's a back up and water gets into the vent, the water is directed to drain out.

Cheers, Wayne
 

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Ok. Here's a mockup with your directions. Minus the elevation, it's about where it all needs to be — the trap is 10" away from the wall and the vent is in the center of the plate.

To answer your question regarding the nailers — yes, they can be cut out to allow for some clearance.

ItPJbh1.jpg


AXb1pId.jpg
 

wwhitney

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Looks OK to me, assuming you verified that at the final elevation as dictated by downstream, the wye + 60 won't come through the subfloor.

If you're not into drilling the angled hole through the joist, looks like you have room in the lefthand bay for a LT90 and a wye (one of them street), so you could use the narrow bay for a pair of 22.5s or 45s to jog.

Either way is fine. Also, if it would really help, the IPC arguably allows a san-tee on its back for a vent take-off, which you could roll 45 off vertical and then use a 45 to go vertical. The wye + 60 is better IMO, but the san-tee + 45 is more compact.

Cheers, Wayne
 

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Looks OK to me, assuming you verified that at the final elevation as dictated by downstream, the wye + 60 won't come through the subfloor.

If you're not into drilling the angled hole through the joist, looks like you have room in the lefthand bay for a LT90 and a wye (one of them street), so you could use the narrow bay for a pair of 22.5s or 45s to jog.

Either way is fine. Also, if it would really help, the IPC arguably allows a san-tee on its back for a vent take-off, which you could roll 45 off vertical and then use a 45 to go vertical. The wye + 60 is better IMO, but the san-tee + 45 is more compact.

Cheers, Wayne
Hmm. Not sure what you mean about avoiding the angled hole. I would come off the trap with a 90 or I would twist the trap to 90?
 

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Also, my mock-up was using 2” going out for the vent. However, I’m planning on getting a 2 x 2 x 1.5 wye/60 so that I can run a 1.5” vent and avoid punching big holes in the bottom plate and double top plate. 1.5” still works for the vent, right?
 

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He means drilling a hole at right angles to the board.

right, that part I understand, I had mentioned earlier I wasn’t keen on going in at an angle. What was unclear is the layout/fitting-combos would afford hitting the joist straight on.
 

wwhitney

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right, that part I understand, I had mentioned earlier I wasn’t keen on going in at an angle. What was unclear is the layout/fitting-combos would afford hitting the joist straight on.
Your shower trap outlet would point perpendicular to the joist. I think the u-bend could still be parallel to the joist, but if that causes the trap outlet hub to actually hit the joist (not just the nailer), then you could rotate the u-bend outlet slightly away from the joist, while still pointing the trap outlet perpendicular to the joist.

Then once you are through the joist, you use up the space in the first narrow joist bay to jog the pipe the pipe closer to the wall with two 22.5 elbows or two 45 elbows (on the assumption it's not close enough yet).

Then once you are through the next joist, you use a wye (or san-tee on its back if necessary) for the vent take off, followed by the long turn 90. Space in that joist bay looks to be tight for two fittings, so make one of the two fittings street if necessary.

Cheers, Wayne
 

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Your shower trap outlet would point perpendicular to the joist. I think the u-bend could still be parallel to the joist, but if that causes the trap outlet hub to actually hit the joist (not just the nailer), then you could rotate the u-bend outlet slightly away from the joist, while still pointing the trap outlet perpendicular to the joist.

Then once you are through the joist, you use up the space in the first narrow joist bay to jog the pipe the pipe closer to the wall with two 22.5 elbows or two 45 elbows (on the assumption it's not close enough yet).

Then once you are through the next joist, you use a wye (or san-tee on its back if necessary) for the vent take off, followed by the long turn 90. Space in that joist bay looks to be tight for two fittings, so make one of the two fittings street if necessary.

Cheers, Wayne
Got it. It looks like it would be best to have the wye and vent come out of that middle narrow joist, so it will hit the right attic joist bay. So I’m going to stick with your original suggestion and go in at an angle.

upload_2021-1-5_19-52-1.jpeg


Off to buy that 2 x 2 x 1.5 wye and get started on boring some holes.
 

wwhitney

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For a long time I never realized why 60 degrees bends were made in DWV fittings. Then I had occasion once to do the trigonometry and realized that they are precisely for this situation, where you have a wye rolled 45 degrees, and want to get back to parallel to one of your principal axes (other than the one parallel to the straight path in your wye, as that would just be a 45).

Cheers, Wayne
 

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For a long time I never realized why 60 degrees bends were made in DWV fittings. Then I had occasion once to do the trigonometry and realized that they are precisely for this situation, where you have a wye rolled 45 degrees, and want to get back to parallel to one of your principal axes (other than the one parallel to the straight path in your wye, as that would just be a 45).

Cheers, Wayne
Yeah, it’s pretty cool to see the angles resolve perfectly as you rotate the wye.
 

Jeff H Young

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that's 100 percent legal I believe . I suppose that could be reason for a 60 degree the less common almost rare is a 5th bend 72 degree , I don't know if that's a specific purpose and never heard of one other than cast iron
 
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