Ask Me Help Desk - Plumbing for addition

As always, excellent advice. Many, many thanks. I have a similar question, how about 2x4 non load bearing walls. Can a 2x4 accommodate a 2" pipe? Particularly the top and bottom plate? Are the restrictions related to the vertical studs, or do they apply to the top and bottom plates as well. This bathroom is complicated in that it has brick walls on 2 sides, a 2x6 exterior wall on 1 side and a 2x4 partition wall on the 4th side. I am having a difficult time trying to figure out how to run the vent stack. Any thoughts?

Also, as long as the stack maintains 1/4" per ft slope, is it OK if it has some twists and turns?

Yes... it's tight but we do it all the time.

Twists and turns are fine as long as pitched. You have to get the vent out somehow.

I'll think on it, but best path is obviously the shortest path!

Mark- I've got a bit of a thread going on in construction regarding how to channel brick. I don't want to double post, would you be willing to check out what I've got over there? The link is

https://www.askmehelpdesk.com/constr...ng-375076.html

Thanks!

Mark-

It's been a LONG time... I hope you're still out there. I can't believe it, but we haven't yet started this project, but hopefully we'll be ready to go in the next month or two.

Recently I have been reconsidering the decision to run the drain pipe along the ceiling, rather than underground, but frankly, I am intimidated about finding the pipe under the cement slab.

How do you go about doing this? I'd imagine you have a camera or some high tech tool, but is there an effective method for DIY? I am certain the pipe is cast iron, but frankly, I am not sure quite how deep the slab is.

Someone suggested I run hot water in the pipe and use an infrared thermometer. Have you ever hear of this?

Would a Radio Shack grade metal detector do any good?

Any other thoughts?

If you look at the diagram in Post # 93, it shows the main level of the home, there is a finished basement below. Immediately below the kitchen (shown in the diagram) is a bathroom. The toilet is in the lower right hand corner, meaning a 3" pipe must run from the toilet to the main stack, also shown in the diagram. I would like to tie into this, it seems like the cleaner installation method.

Any thoughts?

Thanks as always!

Ok folks, I am not sure if I should start a new thread or continue this here because of the history. Hopefully people still bother to read it!

If you look back on the discussion you'll see we were planning to add plumbing for a full bath, half bath and laundry room. We've reorganized the layout and now we only need to focus on the plumbing for the half bath. We'll be adding a full bath and a laundry room, but elsewhere.

So, I have a couple of questions just to make sure that the walls are being designed to accommodate the plumbing correctly, especially for the vent.

So, my questions are...

1) Am I correct that I will just need a 2" vent? The half bath will have just a lavatory and a toilet.

2) I read somewhere that I need to increase to 3" when I come up through the roof, is this true? Or is 2" fine?

3) Alternatively, is it OK if I tie into an existing vent, as long as it is above the flood rim of the other fixtures?

4) If I go the above route and tie into an existing vent, is there any limits on the length of the vent line? I know it needs to be sloped, 1/4" per foot? More? Less?

5) The biggest question though, is can a vertical 2" vent line be run safely and code compliant through a 2x4 exterior wall? Is it code compliant? And, if it is, are there any risks during cold weather, etc?

6) Instead of all of the above, what about an AAV? An AAV seems like the perfect option here, but do they really work? I'd have no problem making it accessible, I could cover it easily with a mirror? Thoughts?

Thanks for any insights. I have lots of architectural plans if they'd be helpful.

Hey Stubby, Back again I see.

Quote:

1) Am I correct that I will just need a 2" vent? The half bath will have just a lavatory and a toilet.

My code, (SPC) will allow 1 1/2" vents but our inspectors prefer 2" vents.

Quote:

2) I read somewhere that I need to increase to 3" when I come up through the roof, is this true? Or is 2" fine?

2" exiting the roof will be just fine.

Quote:

3) Alternatively, is it OK if I tie into an existing vent, as long as it is above the flood rim of the other fixtures?

Not just the flood rim of any fixture. There can be nothing discharging above the fixture you're reventing back into, It MUST be a dry vent.

Quote:

4) If I go the above route and tie into an existing vent, is there any limits on the length of the vent line? I know it needs to be sloped, 1/4" per foot? More? Less?

No limit, 1/4" slope.

Quote:

5) The biggest question though, is can a vertical 2" vent line be run safely and code compliant through a 2x4 exterior wall? Is it code compliant? And, if it is, are there any risks during cold weather, etc?

Are you asking if you can run the vent outside and up a outside wall. Through the over hang and out the roof? Check with your local Building Department.

Quote:

6) Instead of all of the above, what about an AAV? An AAV seems like the perfect option here, but do they really work? I'd have no problem making it accessible, I could cover it easily with a mirror?

Yes they work but it will have to be OKed by the plumbing inspector before installing.
Good luck, Tom

Thanks Tom.

Regarding running the vent through a 2x4 wall, I meant can I run it in a 2x4 exterior wall, sorry for the confusion.

I have read different things about the AAVs, I know they need to be accessible, but do they need to have a vent/grate over them to allow them to breath? Could I install it behind a mirror?

Quote:

Originally Posted by Stubits

Thanks Tom.

Regarding running the vent through a 2x4 wall, I meant can I run it in a 2x4 exterior wall, sorry for the confusion.

I have read different things about the AAVs, I know they need to be accessible, but do they need to have a vent/grate over them to allow them to breath?

Yes, you may take the vent up inside a outside wall.

Quote:

Could I install it behind a mirror?

They do not require a grate over them and if you place a mirror the mirror must be removable or on hinges to provide access for servicing. Ya just can't place it inside a wal without access to it. Regards, Tom

Thanks Tom, I've spoken with our inspection office before and they are OK with AAVs, they say given how many older masonry homes we have, there is not much choice.

Do you trust AAVs enough to use them yourself? As long as stay accessible? I imagine if anything goes wrong all I need to do is cut it out and put in a new one, right?

So, if all I have is a toilet and a lavatory, how high up does the AAV need to be?