Hi there - I know dwv layouts have been beat to death around forums... but each scenario seems to be unique -- kudo's to the plumbers for handling them all... I am not trying to demean their knowledge back tackling layouts myself, I am just a hands-on person who likes to be a know-it-all

Anyway, here is what I am initially looking at, I would appreciate any thoughts. I sketched this up real quick when I had a few minutes... away from my code books & references, so there are no sizes or fitting descriptions because of that.

It is a small bathroom that is draining into a 3" drain stack that is completely separated from the rest of the house and connects right to the city line.

Other than the general layout, my question regards the vent -- since this will be the only vent line on this drain, will it need to be a full 3"? Couldn't remember...

The tub is right next to the toilet, so I assume there isn't a problem wet venting the toilet through the tub vent here.

Thanks in advance!
https://picasaweb.google.com/lh/photo/R9AAUlc7lsI_Q9cd9Qcpt1tAYsgaCUCgDGjJgByTFW4?feat=d irectlink

No 2" is acceptable

Hi there. Couple questions. Is the drain connecting outside to the house sewer, or actually going to tie into the city main? If its going to tie into the house sewer(before it ties into the main), then yes, 2 inch is just fine. If you are actually running a complete new house sewer to the city main just for this bathroom, then (in my area) you would need the vent for the bathroom to be 3 inch. Here's why (according to my 2009 UPC book).

The drainage piping of each building and each connection to a public sewer or a private sewage disposal system shall be vented by means of one (1) or more vent pipes, the aggregate cross sectional area of which shall be not less than that of the largest repuired building sewer, as determined from table 7-5 (in your case, three inch house sewer for toilet, shower, bathroom sink.)

So this basically means that you would need a three inch vent for a three inch house sewer, or the equivalent of that, meaning, for example, two 2" vents and an 1 1/2 vent, but in your case, you are using one vent, the toilet vent, for the venting of the house sewer, the toilet (of course), the shower, and the bathroom sink. This is fine, (as long as your area allows wet venting, which almost all areas do. But as I said, (and remember, codes vary greatly from area to area, so check your local codes) I believe you would be best to run a three inch vent up and out the roof. Hope this all makes sense. Good luck and pop on back for questions.

PS. I would agree that two inch vent would work just fine, but from an inspection standpoint, three would be the safe bet.

Thanks for the help so far --- the code you cited is what I had in the back of my mind about the vent stack itself. I will mock up a more detailed sketch if you guys wouldn't mind checking it out.

As for the answer to your question, it's tough to say exactly where the sewer line goes to -- if I had to guess, I would say it ties back into the main stack somewhere in the floor, but I don't know for sure, the house is 100 years old.

If I did go with the 3" vent to be on the safe side, then wouldn't all of the piping in the whole system I drew have to be 3"? I know you can't transition a vent pipe down in size. Could the vertical pipe going up past the sink be 3" and the horizontal revent from the tub/toilet be smaller?

Thanks again

w/ venting it has to have the same cross sectional area as building sewer or more. If your building sewer is 4" then u need at least 12.56 square in. in vent. in ur case, u have met the cross sectional already and need at least a minimum 2" vent cause toilet requires 2" min. vent. Goodluck

Arqaiu1017, right on. Two inch is all he needs. In his original post, he said the line was going to be completely separate from the rest of the house and connect to the city line, in which case he would need the four inch vent for a four inch drain, or a three inch drain for a three inch drain (or equivalent in cross sectional). However, in his recent post, he said he is not sure where the line ties in, probably under the floor, so it ties into the house sewer, not directly into the city sewer, so a two inch vent is all he needs, like you said because of the toilet.

Just to clarify, I agree with arg, and Markplumber, two inch is all you will need in this case. Up to code and all set. Good luck on your project.

Hi all..

As Mygirlsdad suggested Bauer, if wet venting is approved in your area then it is most common to use the 2" sink drain/vent to vent the lavatory AND wet vent the toilet and the tub drain at the same time. See the basic drawing below... ;)



Mark

OK thanks for the help. Here are some more final drawings. I did realize that the main stack is actually 4" in this room as opposed to 3"...

the one sketch shows the layout of the bathroom, the other the DWV system. My question is the distance between the tub and the 2" vent leaving the Lav -- the diagonal distance from tub drain to sink is a little over 5'... is that too much? I see my tables of critical distances for wet venting -- but not sure which to look at because a portion of the wet vent is in a 4" pipe, which allows 10'... or am I way off here?

Any need for any cleanouts? It's in a crawl space so it wouldn't be very accessible.
https://picasaweb.google.com/lh/photo/REFQmtqJ9BUX-uAkQZL5uFtAYsgaCUCgDGjJgByTFW4?feat=directlink
https://picasaweb.google.com/lh/photo/t7uxVzpSN2KgWmdjj5UJJFtAYsgaCUCgDGjJgByTFW4?feat=d irectlink

Hmm I'll try reposting those pictures...

https://lh3.googleusercontent.com/-BTJJd2u_r4c/Tepy1pyGHSI/AAAAAAAAD2Q/VbpQUUTzhdo/s640/dwv.jpg



https://lh3.googleusercontent.com/-SAJ3G_qjG4g/TepzCfNrp5I/AAAAAAAAD2c/s5XaefCR84E/s400/10a%252520bath.jpg

https://lh3.googleusercontent.com/-BTJJd2u_r4c/Tepy1pyGHSI/AAAAAAAAD2Q/VbpQUUTzhdo/s576/dwv.jpg

https://lh3.googleusercontent.com/-SAJ3G_qjG4g/TepzCfNrp5I/AAAAAAAAD2c/s5XaefCR84E/10a%252520bath.jpg

Hi Bauer...

That wouldn't float in my area as you are discharging a major fixture (toilet) past an unvented minor fixture (bathtub) and this will result in a siphoning of the tub PTRAP which can allow sewer gasses into the home... a major no-no!

What direction do the joists run? Let me know, OK?

If possible, can you run the pipes as shown in the drawing below? If so, use long sweep elbows going horizontal to horizontal and be sure to roll the wye fitting off the toilet drain line above the centerline of the drain, OK?

Back to you...

Mark

Thanks Mark, makes sense with the siphoning... couple questions about your layout though. The joists are running left to right.

First of all, the sewer line goes straight into the ground, approximately between the tub and toilet -- closer to the tub, so in my first drawing - the perspective of the 4" line is down as opposed to over.

1 - as drawn in yours, doesn't that put the tub in a compromised venting situation? I am assuming the pipes coming off the main center one are 2" (?) -- and my sink is over 5' from the tub, doesn't that violate the critical distance for venting? If not, should the wye coming off the lav line to the tub also be rolled up to allow for air?

2 - should I include any cleanouts? Wouldn't the horizontal drain lines require them?

Absolutely correct. Do people really have 2 sewer laterals on 1 property? I aware of a storm drainage and sewer laterals on same property. Thanks again.

Hi again:

1) 2" pipes... correct. The tub vent distance would be measured from the wye picking up the tub drain... NOT to be rolled above centerline for the tub drain... so should be all set on vent distances.

2) In terms of cleanouts, if the pipes are accessible from underneath then you can add some cleanouts where you think you can access them. You could also add a cleanout under the sink.

Finally, if wet venting all fixtures turns out to be tough then just install an individual vent for the tub drain and wet vent the toilet with the lavatory drain/vent and then combine the vents up in the ceiling... (see drawing)... ;)

Back to you...

Mark

Thanks for entertaining my questions Mark, very helpful.

Last (hopefully) two -- just for my own knowledge.

First with venting distance -- so if I am reading correctly you are saying the 'vent distance' would be measured from the trap of the tub, to the wye that connects into the lav line? That would make sense

Second is about the rolling of the wye's --- why does the wye off the main toilet line need to be rolled, but the tub one not? Would I be answering that question correctly if I said that any line acting as a vent (wet vent) needs to be rolled, and since the tub line does not serve as a vent (but the other one does) that it doesn't need to be?


Thanks again - I just like to understand what's going on

J

More than reasonable questions, for sure!

#1) Yes, correct.

In terms of the rolling of the wye fitting (#2)...

All vents are required to roll above the centerline of the drain being served to be considered a vent.

In this particular case of wet venting an entire bathroom group the vent for the toilet needs to be 2"...always a requirement and is why the vent rolls above the centerline. In terms of the tub and the sink drain, the pipe sizes are increased from the normal 1.5" requirement (tub and sink only require 1.5" drains by code) to full size 2" waste and vent piping so the increase in pipe size is considered adequate enough that it allows air to circulate above the drain which in a manner of speaking is almost like rolling the fitting above the centerline of an 1.5" tub drain pipe... that make sense?

Back to you...