Vertical vent pipe directly over ceiling joist

[Carlos Moreno]

I'm adding a bathroom in the corner of my shop. There was a small bath before, which had a 2" vent pipe exiting through the roof, so I want to reuse that roof opening instead of cutting a new one. Unfortunately, when I build the framing, a ceiling joist ended up exactly underneath the vertical pipe to the roof. There will be a 2" vent pipe coming across the ceiling joist (from the plumbing wall with a lav, toilet, and tub) and also a 1 1/2" vent pipe coming over the top of the joists along the near wall (venting a utility sink in the shop). I want both pipes to come together cleanly and exit out the roof.

Attached are photos of the scenario (the existing vertical pipe out the roof, aligned over the ceiling joist) and four possible solutions (just dry-fit). Which should I do?

• Option 1 (2 under san tee): 2" pipe runs along the joist, kicks up and over, then enters under the sanitary tee. 1 1/2" pipe enters from the side of the san tee
• Option 2 (2 under wye): same, but use a wye for the 1 1/2" pipe
• Option 3 (1 1/2 under san tee): 1 1/2" pipe elbows up to enter under the sanitary tee, with a bushing to adapt from 1 1/2 to 2. The 2" pipe kicks up and over and enters the side of the san tee
• Option 4 (1 1/2 under wye): same, but use a wye for the 2" pipe

I think any solution will work...since it's only air...but please let me know if any won't. Mostly I'm asking for the cleanest, most professional-looking solution (so that my inspector and/or future plumbers don't say "who the heck came up with this?").

 

[Plumber01]

Any of those combinations work.

 

[Sponsor]

 

[Carlos Moreno]

Any of those combinations work.

That's good to hear, plumber01. Which option do you like best?

 

[Kreemoweet]

Why can't the 2" vent in the wall come up above the joists, and then run "horizontally" over to the vent-thru-roof stack?
That would be a modified #3, I guess, but with fewer fittings. Nothing says pipes have to run parallel or perpendicular to framing.

 

[Carlos Moreno]

Why can't the 2" vent in the wall come up above the joists, and then run "horizontally" over to the vent-thru-roof stack?
That would be a modified #3, I guess, but with fewer fittings. Nothing says pipes have to run parallel or perpendicular to framing.

Ah ha, good eyes! Yep, the 2" vent pipe comes up the wall, and then over to the left, and then up into the joist bay, and then across. I did consider running it all the way up and then diagonally across the tops of the joists, or even straight across and then over along the near wall. But then we decided to add a skylight to the bathroom, right where the pipe would be coming across. Seemed better to keep the pipe out of the way of the light shaft so I don't have to re-route it later.

I see what you mean about "doesn't have to run parallel or perpendicular". But still, I'd probably try to avoid a diagonal run, just because I wouldn't really like how that looks. I suppose my post is really just a subjective/preference question: which option looks the best/nicest/cleanest, and maybe, which would best avoid scrutiny?

 

[Plumber69]

Just glue it