Vent stack through load bearing stud


  #1  
Old 03-02-24, 12:44 PM
P
Member
Thread Starter
Join Date: Mar 2024
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
Vent stack through load bearing stud

Hello all,

I'm installing a recessed medicine cabinet above a bathroom sink. I'll have to cut a single stud to make room. I understand the process about framing out the opening.

I also need to re-route the vent stack (dry vent) to move it out of the way. It currently runs vertically along the stud that I'm cutting, so I'm cut it and run 45s to route it around the framing. The problem is that I'll have to route the vent pipe through the new king stud. Not sure how to get around this if I even can. The red circles on the bottom pic is where I'm trying to figure.

 
  #2  
Old 03-03-24, 06:02 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 27,764
Received 2,182 Upvotes on 1,952 Posts
Since it is load bearing you can bore a hole through a stud as long as it is no more than 25% the size of the stud. Roughly 7/8" for a 2x4 stud so you can't bore a hole big enough for a vent line. If you've just gotta do all this for a recessed vanity then upsize the framed with 2x8 studs to have enough room for plumbing. With a 2x8 you can bore a hole large enough for a 1 1/2" vent pipe.
 
  #3  
Old 03-03-24, 08:24 AM
P
Member
Thread Starter
Join Date: Mar 2024
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
Yeah, it's currently a 2" pipe in a 2x6 wall. Need to look and see what the code says about changing diameters
 
  #4  
Old 03-03-24, 10:12 AM
P
Member
Thread Starter
Join Date: Mar 2024
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
Wondering if switching to an AAV instead of routing the vent would work?
 
  #5  
Old 03-03-24, 01:07 PM
W
Join Date: Dec 2005
Location: USA
Posts: 2,993
Received 16 Upvotes on 13 Posts
Since it is a vent, would it be acceptable to use two 3/4" pipes through the stud?
 
  #6  
Old 03-04-24, 05:54 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 27,764
Received 2,182 Upvotes on 1,952 Posts
No. The area of two 3/4" pipes is much less than one 1 1/2".
 
  #7  
Old 03-04-24, 06:08 AM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Posts: 27,111
Received 1,921 Upvotes on 1,725 Posts
I'd probably use a couple HSS2-2-SDS3 stud shoes before I used an AAV.
 
  #8  
Old 03-04-24, 07:29 AM
P
Member
Thread Starter
Join Date: Mar 2024
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
I think I could I double the king stud all the way up and then used a 3x shoe (HSS2-3-SDS3)? Overkill? Just don't want to take chances.
 
  #9  
Old 03-04-24, 09:00 AM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Posts: 27,111
Received 1,921 Upvotes on 1,725 Posts
Code indicates that when the hole in an exterior wall is 40-60% that it needs to be doubled.

See boring.

Your king and trimmer are the double below, but you also need that double above the header. (additional cripple) The stud shoe is typically used to restore strength. If the vent pipe was 1 1/2" you would have even less to worry about. (40% of 5.5" is 2.2") Triple it if you want. Remember the vent needs to drain downhill just like any other drain pipe does. So drill your holes at a very slight angle.

And not all stud shoes are created equal. Be sure you're getting the right one.

Your other option is to make an island style vent loop and go down below your bottom plate then back up through the top and bottom plate on the other side of the king stud.
 
  #10  
Old 03-04-24, 10:58 AM
P
Member
Thread Starter
Join Date: Mar 2024
Posts: 5
Upvotes: 0
Received 0 Upvotes on 0 Posts
I'm thinking this is the simplest and most reliable way. Thanks everyone!
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: