DWV Layout for Bathroom Remodel (2)

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Stu27

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geniescience -- Thanks for the thoughts. I see where you were going with that idea now. Let me clear up one detail: the wall for the lav piping is a half height wall that I plan to add to the room for the lav, but it doesn't exist in the bathroom. Figured I'd use a deeper vanity top. The wall you're referring to running the lav drain through is an exterior wall that I was concerned about running any water pipes in due to outside temp, thus the layout avoids sending pipe down that exterior wall. Additionally, I can't get from that exterior wall to under the subfloor anyway due to a large 4x12 solid structural beam below the wall sole plate. The joists are in hangers on that 4x12 so even if I were to run the lav drain under the subfloor in the direction you mention, I'd still have to offset it from the wall to miss the joist hangers as I go through the joists (adding some bends) -- thus the routing in the original tub drain location as shown (one 1/4 bend diff so I chose the already bored route). Perhaps that's the answer though, just to get the vent closer...

Gotta to be a way to solve the shower vent. I'm not giving up, I like the new fixture layout too much...
 

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Inspektor Ludwig

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If you have the shower waste and vent running in the same bay as the lav waste, why not just run the shower trap arm straight over and tie into the lav waste, (3rd image up) and eliminate your shower vent. You would have to increase the lav drain to 2" at the tie in point but you'd be doing a horizontal wet vent correctly and eliminating the need for a seperate shower vent. The wet venting you have in the following images would probably work but I don't believe it would meet code for a horizontal wet vent or a vertical wet vent for that matter. If you're at all confused by all of the suggestions, the image you have with the seperate shower vent (3rd image up from this post) is by all accounts correct and to code. Although it's not the leanest method of installation, you've met basic code so if you're having any doubts about your layout, use that plan as your fail-safe and remember to use sweeps and combos/wyes under the flood rim of the fixture (that includes vents underfloor too) and always use santees on a lav trap arm tie-in to a vertical waste and vent. Hope this helps, good luck!
 

Geniescience

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Combine the shower to the wet went (lav) prior to the second bend in 3rd image up (09-25-2010 mid day), if you can. This is what I understood of Inspektor Ludwig's post.

Doing this will shorten (significantly) the shower trap arm. Since it becomes a vented drain at an earlier point, it drains better when the water is beginning to pile up and is beginning to push a path through the air and start flowing. Eliminating one bend and covering a shorter distance, prior to the first vent is a big improvement.

If you cannot please post why you cannot.
A went vent is good, not a poor substitute. Worry not.
Keeping the extra vent is OK. It's not forbidden.

hope this helps
 
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Stu27

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Inspektor Ludwig -- makes complete sense to me now -- tying the shower trap arm to the lav waste… (and as far back as my first post, HJ pointed out that the second vent (2") was useless -- it just took me this long to understand (i) that I didn't need a dedicated shower dry vent, that wet venting off of the lav drain would work just fine, and (ii) as Wally Hays pointed out… a vent has no impact on the performance of a drain… and I now know that its intended function is to prevent the trap from siphoning).

well… you can lead a horse to water… but sometimes he's sloooowwww to drink…

Wally Hays -- in the latest pic, the shower drain is now only about two feet from the horizontal lav wet vent and about four feet from the vertical vent pipe.

nukeman, geniescience -- did you mean 2" for the lav drain if wet vent? my interpretation was increase the 1.5' lav drain to 2" starting at the base of the sanitary tee to the shower trap arm tie-in.

I used a 2x2x1.5 reducing sanitary tee on the lav drain/vent/trap-arm which has a 2x1.5 bushing in the top to attach the vent pipe. Is a bushing the proper fitting here, or should I use pipe increaser/reducer? or something else? does it matter?

Thanks again for all the input! I've included a new pic, that shows:
- the shower wet vented off of the lav drain
- the lav drain upgraded to 2"
- all drain/waste direction changes are long sweeps, combos, or wyes (except the 3" waste offset which is two 1/16 bends to line up the toilet flange)
- sanitary tee on the lav drain
- and only need one new joist hole for the shower trap arm

There's light at the end of this here tunnel…
 

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Nukeman

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It is getting there.

Couple things:

- toilet dry vent is not needed, but since you have a wall there and you need to vent the other bath and laundry anyway, you might as well keep it.

- I think you'll have an issue with those two 90* horizontal fittings on the shower/lav line. If you keep it this way, you'll need a cleanout (see Section 708 of the VA code).

Can you keep the shower/lav line straight, then add a 45*, and come across at an angle and connect to the toilet line on the right side? I wouldn't worry about having to make new holes in the joists. You could always sister the joists that currently have holes and then make your new holes.
 

Stu27

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hmmm… cleanouts.

Here's an adjustment to the drain layout that I believe addresses the cleanout requirements. Puts the drains back at 45deg. What'dya think?

Tweaked the new vent -- previously, the vent was going straight up through the wall top plate (but it's an exterior wall - so very close to the soffit/roof - limited access). Should be easier to work up there if the penetration is not so close to the soffit.
 

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Stu27

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as an aside -- here's the original bathroom layout…

no cleanouts and a long (5-1/2 ft) 1.5" tub trap arm to get to the lav wet vent. VA allows a run of 6' from trap to vent on a 1.5" trap.
 

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Geniescience

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straight lines in the latest draw; looks good. Yeah. New holes.

What about a cleanout just for good measure?
1/ In the new half wall near the (lav to vent) San T.
2/ Keeping the old lav vent and connecting it for extra vent + cleanout (instead of the WC vent)
 

trinitony

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I've a question on the 2 photo above this post which I think is the final. It's somewhat similiar to my remodel.

Let's pretend that no lav' and venting for it exist in that photo, would it be still necessary to vent the shower even if you're using 2" pipe? My shower will be draining in that fashion and I was about to vent it this weekend, but reading some of the above post I'm not sure if venting it is required. I'm a lil confused here..lol

Apologies for the question..
 

Stu27

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geniescience -- good call on re-using the old lav vent. it is spot-on centered over the new shower drain and it is 7'-2" from shower trap weir to center of vent pipe (8' trap to vent on 2" trap for VA).

Can I now go back to 1.5" on the new lav drain down to its tie-in point near the shower trap (I think I can do so if the shower is vented using the old lav vent)?

Thinking about the lav clean-out... It needs to be accessible, right? wondering if I can put it below the san-tee and have an access panel inside the vanity?
 

Geniescience

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stu, I'll say yes to those questions, and also I'll say that you still need another responder with a Plumber's license, and then you need to confirm this in real life too.

I think the two 1/16 bends will be unnecessary because there is enough give in the PVC and fittings.
 

Stu27

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thanks for the new ideas! allows for a much more efficient drain layout. a few changes since the shower can be easily dry vented down the joist bay to the old lav vent and the WC dry vent is not needed (wonder why it originally tied into the 3" waste at all...)

- removed one of the two 1/16 bends from the 3" waste (rotated the 1/4 bend under the flange now that the 3x3x2 sanitary tee tying 3" waste to old 2" vent is gone)
- removed bottom half of 2" vent stack (dry vent not needed for wc)
- added back the old lav vent for new shower vent (dedicated dry vent for shower)
- new lav drain back to 1.5" pipe

Do I need to increase the old lav / new shower vent to 2" from the combo all to way to the existing 2" vent?
Still thinking about the cleanouts...
Crazy... but seems worth it.
 

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Inspektor Ludwig

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Ok, this doesn't look so good. The picture you posted on 9/27 is by all mean correct with regards to a code compliant horizontal wet vent. I would stick with that layout, of course what you have above is wet vented in the horizontal position it would not pass inspection in my area. The UPC and IPC are pretty similar when it comes to the design of the horizontal wet vent. The idea is that you have one main drain that starts at the lav then going down and having the trap arms of the shower and then the toilet tieing into the main drain, not the other way around. Take the picture above for example, imagine the drain that runs from the shower to the toilet as the "Main Drain", now that horizontal drain on the upstream side would go vertical to pick up the lav, then turn into the dry vent and out the roof. Follow the flow of the lav trap arm 1-1/2 into the vertical waste "Main Drain" and continue downstream into a sweep and starts it's horizontal run in 2", it then picks up the shower trap arm (5' max) and continues 2" down to where the toilet trap arm would then tie into the "Main Drain" and at that point would increase to 3" and then continue 3" from there. Picture a tree with all of these branches picking up the fixtures one at a time and joining the main trunk line. So you only have 1 vent for the whole system which would be the vent off of the top most fixture (lav). The tie ins from the trap arms (branches) would tie into the main line (trunk) by an invert to invert wye, all tieing in at seperate points along the trunk. When you tie in the trap arms at the same level you are in a way creating a flat vent but you need to do that so that air can circulate in the upper half of the drains while the waste water is flowing in the lower portion. You should have a free circulation of air at all times to all trap arms through out the main trunk and eventually be dry vented off the top of the lav. Maybe another plumber can draw what it is I'm saying. For the sake of simplicity, I would go with the drawing you showed on the 27th. Sorry I'm having hard time explaining, it's been a long, long day of explaining plumbing to non-plumbers.
 
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