Need advice on DWV venting

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Matt1988

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I have searched the web and forums trying to find an answer for this on my own without any luck. I'm in the middle of building a new house and am starting on finishing the plumbing rough in before we start insulating. My rough sketch should give you guys an idea of what I'm asking. We roughed in the plumbing before pouring the slab and the builders set the girder trusses on the wrong side blocking my vent pipes so now I'm trying to figure out if I can run the stack on the first floor horizontal for about 5 foot before going vertical thru the roof. It is still possible to run this vent vertical as is but it will be a large amount of extra work and take some space from the room above to hide the plumbing. The dotted lines is the two options I have to vent the main stack. It starts as 4in pipe and I was thinking of reducing it to two inches to complete the run to the roof. Any advice is greatly appreciated. I have used this site a lot since we started this project and it has helped me a great deal already. Thanks to all who contribute here!
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Matt1988

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I know my drawing wasn't that good so hopefully this will help draw a better picture of what I'm doing. The 1/2 bath on the second floor will have its own vent going thru the roof and the vent next to the tub will tie in with the stack vent on the second floor. My question is can I reduce the soil stack to two or three inches and 90 off and run it horizontal on the first floor? If not I plan to 45 the stack vent to the second floor and join it with the other vent in the pic and take it out of the roof at 2inches. I just want to know if this will work before I start cutting and gluing pipe? Is there any code violations I might have overlooked? Thanks again
 

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FullySprinklered

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Last time I saw something like this, the guy wanted an estimate to finish up the job. I e/m'd him back later and told him I didn't have time to fool with it. He ran out of know-how and needed to be bailed out. Personally, I need some continuity to carry a job through to finish, and it's hard to jump in and work out problems on a job already underway. If I'm doing a job, it's my job, and I'm totally responsible for making it turn out right.
 

WorthFlorida

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I agree with fullysprinklered. A job like this you should have a licensed plumber because when it comes to an inspection there could be many other problems you're not aware of. A local plumber would be aware of the little nuances that the local inspector looks for. I applaud you for trying this yourself. Homes are not cheap but education is also expensive.
 

WorthFlorida

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Looking at your picture, the vent near the tub, it that 2"? It looks smaller, like 1 1/2 inch. I'm not a plumber but I think vents cannot be less than 2". Also the drain for the sink, if that is straight down then you'll need an S trap. I think S traps or no longer legal. Maybe a plumber here can comment. Was there an inspection before the concrete was poured? If it was then you might be OK.

Another look and it looks like your have 2x6 wall, therefore, it maybe a 2" vent.
 

FullySprinklered

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Hope I didn't bite down too hard, but it's hard for me to understand someone learning how to plumb a house only to do it once.
 

Matt1988

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Last time I saw something like this, the guy wanted an estimate to finish up the job. I e/m'd him back later and told him I didn't have time to fool with it. He ran out of know-how and needed to be bailed out. Personally, I need some continuity to carry a job through to finish, and it's hard to jump in and work out problems on a job already underway. If I'm doing a job, it's my job, and I'm totally responsible for making it turn out right.

Ran out of know how and had to be bailed out huh??? My rough in b4 the concrete was poured was inspected and it was passed and my question was a VERY SIMPLE ONE. I even added in my FIRST POST that I already had a solution in case I couldn't run the pipe horizontal like I was asking about and as far as assuming I just dove in to "learning plumbing for one little house" ?? I did have some help from someone who has worked in the business btw. All of that is under the concrete obviously?? Or so I thought? What I have left is not anything that anyone would have to be "bailed out from" and the issue arose from the trusses being set incorrectly? Not me getting in over my head? UNBELIEVABLE? I could understand if there was something here hopelessly wrong but if there was IT WOULDVE BEEN POINTED OUT BY NOW RIGHT?? Surely these two plumbing MASTERS would've EMPHASIZED a mistake if they had seen it already? I have no doubt of this. Hopefully there are some guys here that can actually offer something productive because my first experience in posting here shouldn't had been meeting a couple of Internet Rambo trolls. Keyboard tough guys! LMAO!!

Btw if you have a job and its your Job,responsibility,period then why would you even participate in a site like this where you know people will eventually sign up to ask a question? If it's your job your responsibility! All or nothing or call a plumber then why in the world would you participate in a site where you will inevitably have to give someone advice at some point? Sounds strange to me?
 

Matt1988

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Looking at your picture, the vent near the tub, it that 2"? It looks smaller, like 1 1/2 inch. I'm not a plumber but I think vents cannot be less than 2". Also the drain for the sink, if that is straight down then you'll need an S trap. I think S traps or no longer legal. Maybe a plumber here can comment. Was there an inspection before the concrete was poured? If it was then you might be OK.

Another look and it looks like your have 2x6 wall, therefore, it maybe a 2" vent.

It's 2in buddy. It was inspected. Appreciate the 2nd guessing w/o the help lol
 

Matt1988

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Looking at your picture, the vent near the tub, it that 2"? It looks smaller, like 1 1/2 inch. I'm not a plumber but I think vents cannot be less than 2". Also the drain for the sink, if that is straight down then you'll need an S trap. I think S traps or no longer legal. Maybe a plumber here can comment. Was there an inspection before the concrete was poured? If it was then you might be OK.

Another look and it looks like your have 2x6 wall, therefore, it maybe a 2" vent.

I need an s trap but thats no longer legal? That doesn't make sense but a p trap is what I plan to install when I install the sink? It goes right under the sink and is not normally included in the rough in.
 

Matt1988

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To anyone that reads this nonsense afterwards I tried to come in here with all of the appreciation and respect I thought was deserved here. I've read posts of diyers on this site almost every time I've been here. Never seen or read the disrespect and abrasiveness that I had to just deal with. If I had I would've never wasted my time in signing up.
 

Matt1988

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Looking at your picture, the vent near the tub, it that 2"? It looks smaller, like 1 1/2 inch. I'm not a plumber but I think vents cannot be less than 2". Also the drain for the sink, if that is straight down then you'll need an S trap. I think S traps or no longer legal. Maybe a plumber here can comment. Was there an inspection before the concrete was poured? If it was then you might be OK.

Another look and it looks like your have 2x6 wall, therefore, it maybe a 2" vent.

I'm sorry I can't help myself but isn't the smallest vent size 1 1/4? not 1 1/2. It is I'm sure of it. Or no less than 1/2 the size of the drain it's serving.
 
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Plumber01

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The 4" coming out of the slab does nothing for venting nor does it need to go through the roof. You call it a"stack/wet vent", you can not wet vent between floors. It is a drain. All fixtures must be vented. You can run as many vents through the roof as you want, you just have to meet the cross sectional area of the main line leaving the house.

I understand why the poster above was questioning the sink. The drain is out in the middle of the floor with no vent.

Hard to tell how the underground was plumbed, specifically the tub and toilet which appear to be sharing a vent.

To answer your question- Sure. Run it horizontally to pick up the toilet and lav. The lav can wet vent the toilet if it is within 6 feet on 3" pipe. The drain and vent on that particular lav must be 2".

This is assuming you're using the correct fittings and practices. Local jurisdictions vary widely with codes and inspectors.
 

Terry

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All of the sinks will need vents.
The vents can revent at 42" above the floor that they are on, or if going to the next story, then 42" above that floor.
Lavs can wet vent tubs, showers or toilets.
There is no wet venting between floors.
Wet venting is only for bathroom fixtures, not for kitchen sinks or clothes washers.
On the cross sectional, if you have three inch going out, then you will need either a single 3" vent, or two 2" and one 1.5" which will equal a single 3".
Most homes I plumb I wind up with that, two 2" and a single 1.5" which is normally at the kitchen sink.
 
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Matt1988

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All of the sinks will need vents.
The vents can revent at 42" above the floor that they are on, or if going to the next story, then 42" above that floor.
Lavs can wet vent tubs, showers or toilets.
There is no wet venting between floors.
Wet venting is only for bathroom fixtures, not for kitchen sinks or clothes washers.
On the cross sectional, if you have three inch going out, then you will need either a single 3" vent, or two 2" and one 1.5" which will equal a single 3".
Most homes I plumb I wind up with that, two 2" and a single 1.5" which is normally at the kitchen sink.

Ok thank you. This is very helpful. My kitchen sink is planned to have an air admitinance valve (approved by my inspector already) and I will have to run an additional vent for the washer as well. only a 1/2 bath up top. Thanks I really appreciate it. My only other question is that I'm trying to keep as much of the plumbing between the floors as possible without having to build soffits in more than just the bathroom. I knew I'd have to build a tray ceiling in the bathroom to hide some plumbing but I thought there might be a chance I'd have to do the same in the hallway and master bedroom. The two pics I have attached are two ideas I had on bringing the 3in pipe from above the top plates to below inside the bathroom. I can't drill any holes in the floor joists due to them being part of engineered trusses and the manufacturers plans states no holes of any size. The second pic will include a clean out that I know I will have to include access to. I can run this straight to the stack without the turns if this won't work but this would look better cosmetically if i can run it this way. Sorry if this is remedial to anyone this is just the stuff that i personally have found hard to locate in the books and need someone experienced to help. If it's in the books or codes please by all means I am all ears! Thanks
 

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Terry

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Not seeing it all, it's a bit hard to advise as to whether you can fit those pipes in there.
With some homes with joists that I can't drill, I keep the runs near the wall where a sofit isn't so noticable. HVAC has the same problems hiding their heat ducts. When I was building homes, I would run stuff near the walls, and then sofit four walls like it was my idea in the first place. I would make it look really nice and corner mold the heck out of it. Nobody ever knew I was hiding ducting and piping.
 

Matt1988

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Looking at your picture, the vent near the tub, it that 2"? It looks smaller, like 1 1/2 inch. I'm not a plumber but I think vents cannot be less than 2". Also the drain for the sink, if that is straight down then you'll need an S trap. I think S traps or no longer legal. Maybe a plumber here can comment. Was there an inspection before the concrete was poured? If it was then you might be OK.

Another look and it looks like your have 2x6 wall, therefore, it maybe a 2" vent.

I see what you were talking about the s trap. Sorry about b4 but after reading that first reply last night it just frustrated me. Looks like I messed the sink drain up. Can I 45 this drain back into the wall and run it straight up to vent it correctly and run a drain off of it from back in the wall like it should had been originally? Then I can avoid making an s trap out of it? I know it will take up cabinet space and will look shoddy but going back into the concrete is not an option or I sure hope I won't have too. I did try to hire a plumber in the beginning btw. Talked to a few and then I had a friend who had a friend who said he worked as a plumber for a long time and I trusted him to help me. Maybe that was a mistake but I'm doing my best to get this right at this point.
 

Matt1988

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According to your isometric drawing the sink and kitchen sink on the lower level are not vented.


The kitchen sink is going to have an air admittance valve and yes your right about the bathroom sink. I thought having it close to the 4in vent would work but I see now that it's been goofed. Could I put a 45 on it low on the concrete to run it back into the wall as a vent then run a drain off of it horizontally back into the room? Oh man I thought our concrete rough in was correct when it was poured. It'll be a disaster if I have to dig it back up...
 

Matt1988

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Almost scared to show this now. Lol but looks like I better before I do anything else. This is the piping under the concrete. Someone said there's no wet venting between floors so I'm worried about adding the 1/2 bath now? The 4in vent was meant to be for the water closet but there's also a 2in vent that was placed after this picture was taken. Can I still add the half bath up top with the way we laid this out??
 

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