Rerouting Vent Stack

[amcculidis]

Hello,

I would like to install a recessed medicine cabinet. The bathroom is located on the 2nd floor in the house built in 1992. Can I reroute the existing 3" vent (red) to the location shown in green while having the 45 angle starting below the flood rim? I just learned here that the horizontal line needs at least 6" from the sink but that unfortunately doesn't work for this medicine cabinet (too high after 3" plus 6"). I am hoping this 45 angle is acceptable but I'm not sure.

I would appreciate any advice/suggestions. Thank you!

 

[wwhitney]

45 degrees off vertical is considered vertical, so yes, you can jog the vent with 45s below the flood rim of a fixture served by the vent.

However, what is the framing depth of the wall, at least 2x6? Cutting a diagonal 3.75" or 4" hole through a 2x6 stud will be tricky. So if you need to pass through a stud, a little reframing might be in order. A picture would help.

Cheers, Wayne

 

[Sponsor]

 

[WorthFlorida]

If it is a supporting wall, an extra stud maybe needed to the left of the rerouted vent pipe.

 

[amcculidis]

I’m grateful for your comments. I have added additional photos. Yes…the studs there are 2x6 and it’s tricky and probably not to code even if I bore with a perfect angle? The wall is load bearing to the secondary/smaller gable roof, which is housed inside the main roof (not closer to the front window, but under the ridge of the main roof running perpendicular).

My follow-up questions will be:

1) Do they allow using 2” pipe for the rerouting section (reduce to 2” then back to 3”) to allow smaller boring diameter in studs?

2) Would doubling studs with applying stud shoes help?

3) When we re-enforcing the stud, do I normally disconnect and reconnect the existing electrical wire and pex pipes or can I notch the additional stud?

Thanks again

 

[Jeff H Young]

cant shrink pipe down for that. Framing issue Im not a framer but sounds like 2 studs are getting cut and a 4x6 min or 6x6 header needs to go in not just a single flat 2 x6 . the header probebly will be getting drilled out with a 3 5/8 hole so out of ignorance Id say a 6x6 header. I know overkill . but your the boss and Im no framer. also it may require pulling cabinet

 

[WorthFlorida]

I believe you can turn 90 degrees to the left then 90 degrees up as long as this is a vent only. There must be slope toward the drain for rain water or condensation can drain.

https://terrylove.com/forums/index.php?threads/how-far-can-a-vent-run-horizontal.8007/

 

[wwhitney]

Looks like the vent is for the lavatory there, so it shouldn't turn horizontal until a height of 6" above the flood rim level of the sink. But perhaps that's low enough for the medicine cabinet to still fit.

Cheers, Wayne

 

[WorthFlorida]

Just might be easier just to surface mount the medicine cabinet or just attach it to the stud. You'll only gain 1/2" but would you'll need to replace the faucet with a low profile spout or install the cabinet above the faucet. I've had several homes with surface mounts, not all that bad. Possibly recess it over the toilet? Just a suggestion.

Rules for notching studs. Don't forget to use nail plates. If you really have to notch further, with a 2x6 notch it out and slide it in over the wire or pipe and scab that to the existing stud.
https://up.codes/s/drilling-and-notching-of-studs

 

[Jeff H Young]

dont forget the stud in the middle is getting cut in half. so I think we are talking about more than a notch on one stud. these arent that major but will need some attention

 

[wwhitney]

A related question is how deep the cabinet is being recessed. If it's only 3" to 4" relative to drywall, notching the middle stud is much more than prescriptively allowed, yet the remaining portion of the member has some value. And if the wall were open plate to plate, you could sister in a flat-wise 2x4 and call it good.

If the cabinet is only being recessed 2-1/2" or less, you could in theory jog the vent pipe against the rear drywall and just install the cabinet in front of the vent pipe. If the medicine cabinet has a finished flange around the perimeter that is to lay over the drywall, you could reduce the recess by building a finished frame that goes over the drywall. Then cabinet flange would lay over the new frame.

Cheers, Wayne

 

[amcculidis]

Thank you for the input. Is the exposed section of the stack considered dry/air only or wet when all it does is venting to the roof above? The vanity pictured is the last fixture connecting to the vent stack. In other words, does "6 inch above flood level rim" apply to the highest fixture that this stack serve? Everyone here is so helpful. Thanks again.

 

[amcculidis]

We knew about the vent behind before removing the sheetrock. I wanted to see what kind of work other than framing I will need to have it recessed (do-able but obviously a lot). Nice to hear surface mount is not as bad. Thanks again.

 

[Jeff H Young]

pretty common on side wall as well. then just put a flush mount mirror on wall in back wall of lav

 

[WorthFlorida]

How is this project going? I forget about these and it can be used if you need to notch a stud. Google stud shoes.

https://www.homedepot.com/p/Simpson...u53g8Jn0Wkl00k994T3FxiRDpepPXN_dvoTi5vwqcd19A

 

[WorthFlorida]

Thank you for the input. Is the exposed section of the stack considered dry/air only or wet when all it does is venting to the roof above? The vanity pictured is the last fixture connecting to the vent stack. In other words, does "6 inch above flood level rim" apply to the highest fixture that this stack serve? Everyone here is so helpful. Thanks again.

If there is nothing above draining into this vent from above, it's a dry vent. The northern snow states require three inch vents through the roof to prevent ice building up from condensation above the roof thus blocking the vent as more likely it could happen with a two inch vent. Usually a 2" pipes are used for venting then to a 3" in the attic space.

Yes in this case, the highest fixture. You want to prevent waste water from entering a vent should a back up ever occur.

 

[amcculidis]

Thank you WorthFlorida for following up on my case. I’m currently looking into a half-recessed option below. It requires the least work and I may be able to live with some of the cabinet sticking out.

1) Notching the existing 2x6 middle stud by 2 inch
2) Sistering 2x4 into the right side of the 2x6 (facing the sink)

I do not see a restriction on length/height of notches although I'm not sure if that matter or not. 2" is beyond the max depth code allows on load bearing 2x6 (1 -3/8" @ 20%) but sistering 2x4 can make it acceptable? All interior load bearing walls (non-bathroom) are 2x4 in our house. I have a way to shift the vent all the way against the rear drywall so the part of the medicine cabinet can sit in front of it.

 

[Jeff H Young]

see that stud in the middle its getting wacked in half . it needs headed out a 2x6 or 4x6 6x6 something?
just wondering where your at any more pics?

 

[wwhitney]

1) Notching the existing 2x6 middle stud by 2 inch
2) Sistering 2x4 into the right side of the 2x6 (facing the sink)

I do not see a restriction on length/height of notches although I'm not sure if that matter or not. 2" is beyond the max depth code allows on load bearing 2x6 (1 -3/8" @ 20%) but sistering 2x4 can make it acceptable?

Sounds like the only reason the wall is 2x6 is for plumbing, and structurally it could be 2x4. So substituting a full length 2x4 for a 2x6 is fine. The notched 2x6 may not be as strong as an unnotched 2x4, so it is good to sister it.

If you are going to just scab on a shorter length of 2x4, then a calculation should be done for what the fastener pattern should be in the overlap region between the 2x4 scab and the unnotched 2x6 at each end. Easier just to use a full length 2x4, if you can.

It will be a little tricky to get the 3" pipe against the rear drywall, because the outer diameter of a 3" hub is bigger than the 3" pipe. So if a hub above or below the medicine cabinet is against the rear drywall, the pipe will want to be a little bit off the drywall. That means it would be easier to recess the medicine cabinet 1-1/2" or 1-3/4" than a full 2".

Cheers, Wayne

 

[Jeff H Young]

post 4 says it is load bearing. dont know if I missed where this wall is non structural ? there are ways to adress it all of which are the responcability of owner. I see several safe options but not really qualified to share

 

[wwhitney]

Sure it's structural, but the only wall in a wood framed single family house typically required to be 2x6 would be one carrying two stories above it, which this wall is not. So substituting in one 2x4 for a 2x6 isn't going to be a problem.

Cheers, Wayne