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dcgray2 06-15-2006 01:04 AM

DWV Stack Question
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After much frustration and deliberation I have decided to attempt to do some plumbing I need myself.

I am working on the design but could use some advice for a tricky portion of the build.

The "addition" in which the plumbing is being done has three floors and has 6" framed walls and a 12" block foundation (I built it to last...). I want to run a second DWV stack for the addition for lots of reasons which I can explain if need be.

The upstairs has a master bath, the second floor has a guest bath and a kitchen, and the basement has been built out as a media room.
Now to the tricky bit.

I want to run the DWV stack behind the toilet in the master bath straight down to the basement. I also want to run a horizontal 3" line on the second floor (basement ceiling) for the guest bath that meets up with and then becomes the DWV stack connection to the DWV stack in the old part of the house. Think upside down "T" with the guest bath toilet on the right, the DWV stack in the middle, and the old house DWV stack at the end of the left branch.

If I had a "normal" basement this wouldn't be an issue. But because it was built as a media room their are a couple of things to deal with. There are 10" joists running left-to-right when looking at the DWV stack which is great. Those joists sit on top of a 12" steel beam (running front-to-back) to avoid the need for supports. The DWV stack would be just to the right of this beam. The wall that is the DWV stack wall has been framed out 10" from the block to hide the pilaster that the beam sits on because that wall is the projection wall. Ceiling height is a concern and a true 8' ceiling height (what I really want) can be acheived by boxing and drywalling on the bottom of the beam. So I need to run the DWV stack (inside the wall) down into the basement. But it needs to go from being inside the wall at floor level on the second floor to teeing up to that horizontal branch (I am planning on using a combi wye and 1/8 bend... Is this right?) running from the guest bath that is 16" away from the wall (I'm planning on using an offset closet flange to clear a joist, otherwise it would be 20" away from the wall). And since I REALLY want to run the horizontal branch OVER the steel beam this gives me 10" of vertical space to move a 3" pipe 16" horzontally while teeing into the top of another 3" pipe.

I'm pretty sure that just isn't possible. If it is I would love to hear how!!!

If it isn't, I have an option which is perfectly acceptable to me but wanted to get some feedback on. I can start moving the pipe above floor level. I can even go so far as moving the pipe the 16" away from wall entirely above the floor level. If I did this with 1/8 turn long sweep elbows, the pipe would be exposed for a height of 16" and a depth of 16".

The room this would occur in is a pantry. So like I said to me it's perfectly fine. But what would a real plumber say? I'm in PA and we don't seem to have much of a code in my area, but I would like to stick with "best practices". Should I use 1/4 turn long sweeps instead to keep the pipe as low as possible? Is this safe from a clogging standpoint?

Any help would be appreciated. I have attached an overhead drawing of the guest bathroom that may or may not help.

Ron The Plumber 06-15-2006 06:47 AM

Can you post some pictures of what your looking at?

Add text to them, showing what you want to accomplish, pictures can tell alot.

dcgray2 06-15-2006 10:31 PM

Thanks for the feedback. I have posted three pictures:

Perhaps I am making a mountain out of a molehill, but I couldn't find the "answer" to whether or not exposed plumbing was a bad thing... IF I do in fact end up needing to have to make the 16" transition ABOVE the floor rather than below it as would normally be done.

I also posted some drawings to try and help you get your bearings:

Thanks for any help.

Ron The Plumber 06-20-2006 06:18 PM

Trying to explain what you need to do here online is too much, your best option is to call someone local have them come take a look and get advice from them.

dcgray2 06-21-2006 10:44 PM

Time is on my side...
I appreciate you trying. I think I finally figured it out after buying an assortment of pieces and playing with them...

What I am planning on doing is running the 3" stack down to a sweep 1/4 turn that will be rotated approimately 30 degrees off perpendicular. Then I will run a 12" length of 3" pipe to a 1/8 turn street ell that has been rotated 1/4 turn inside a 3x3x3 wye that will be tilted 45 degreees off center on its axis.

I'm pretty sure this will allow me to cram everything in 10" of vertical space with a minimal exposure (above sub-floor level) where the sweep transitions to horizontal (due to the fact that the horizontal hub of the sweep needs to be hard against the underside of the sub-floor).

If you can visualize this does this sound OK? To do this I need to drill a 3/12" inch hole in a 10" joist. Which is a major faux pas. What is the proper remediation for this? I can't really box the joist, because that just creates the same issue for the box joists. Can I double it up for some length?

One other area where I need to be creative, and you may be able to provide some feedback, is for the master bathroom.

I have the closet bend going into a sintary tee with a super short section of 3"pipe below it connecting it to a 3x3x2x2 double wye. I want the 2" branches and the sanitary tee to be completely within the 12" joists below the master bath. To make room for slope from the closet bend and ensure that any holes for "threaded" 2" branch pipes are 2" from the bottom edge of the joists, I cut some 4" sections of 2" pipe that I put in the wye branches. This fits between the joists with enough room for the hubs of a street 1/8 turn on both branches to fit between the joists. I planned on drilling 3" holes in the joists to allow the 1/8 turns to fit into the joists and then use a coupling to connect the 1/8 turns to sections of 2" pipe.

Does this sound kosher? Am I going to have / cause problems by connecting the couplings to the 1/8 turns? Does the fact that they are somewhat "inside" the joists matter?

Once again, I am a total plumbing noob so any feedback is appreciated.

manhattan42 06-22-2006 06:47 AM

Code In Pennsylvania

I'm in PA and we don't seem to have much of a code in my area, but I would like to stick with "best practices".
Pennsylvania mandatorily enforces the International Resdiential Code Plumbing provisions and the Code is enforced in your jurisdiction, so you do need to comply with plumbing code.

Your best option is to contact your municipality's code enforcement office to have the Plumbing Code inspector review your permit application for your plumbing work.

I'm a Pa. Certified Plumbing Code inspector and I, like Ron the Plumber, can't make heads nor tails of what you are trying to do.

dcgray2 06-23-2006 09:16 AM

Thanks for the advice.

dcgray2 07-05-2006 05:41 PM

Inspector says Good!
Just to follow-up on my previous posts...

I took the advice and downloaded and read the plumbing code before starting and spent a lot of time thinking through everything.

I spent the last week getting everything fitted up.

I had a "pre-glue" walk-thru from my inspector today and he said everything looked fine.

Ron The Plumber 07-05-2006 05:46 PM

Thats good to hear, and best of luck to you in your project.

ThePlumber 07-14-2006 12:56 PM

hi dcgray im just wondering what program you used to create that plan view of your bathroom, it looks pretty spiffy right down to the correct dotted green line for the vent and I wouldnt mind using something like that the next time I go to trade school. :thumbsup:

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