Hello,

This is my first time posting, but I've been lurking for a while in the plumbing area. Anyway, I want to add a basement bathroom, but have some questions. I had a plumber come over in December of 2007 to give me an estimate on running the drain and vent lines only. He estimated about $1000 for the drain lines only for a tub, vanity, and toilet. This also included venting them all, as it should.

The main thing that I'm wondering about is the venting. I would like to be able to at least be able to connect a vent and run it to the basement and cap it off until he's able to do his work, which means the plumber will just have to deal with the basement work and won't have to tear apart our existing bathroom to get into the vent pipe. The existing layout is a 3" cast iron stack that goes below the slab, and then changes to a 2" galvanized pipe just before it goes up to the floor where the bathroom above is. To service the basement bathroom, could I tie into the existing galvanized vent above the flood rim level of the first floor sink, and then just run some 2" PVC to the basement and glue a cap to it? Would a
2" vent be adequate for a toilet, sink, and tub? AAVs are not allowed in my area, I confirmed that with the plumber when he came over.

Alternately, if I can't tap into the existing galvanized pipe, I could always run a brand new separate vent. But again, would 2" PVC be adequate for the fixtures I plan on downstairs?

Thanks in advance for any help. Hopefully this isn't too confusing, I'll be glad to clarify if needed.

Hi Brett:

Let me see if I get this. That 3" cast iron drain comes out of floor and then reduces to 2" galvanized pipe and then runs upstairs to bathroom.. right?
This pipe sounds like a waste line to me... need to open the wall upstairs and see where it goes... If waste.. do not cut into it. If just connects into the vents upstairs, your plumber should be able to connect onto it as a vent without doing anything upstairs (all work would be in basement)... but only if that galvi. Pipe is a vent (I doubt it).

Anyway, you said connect into vent at upstairs bathroom by connecting above the flood level rim of the sink... THAT IS CORRECT... want to connect at minimum 6" above the flood level rim..ok? A 2" pvc vent pipe is all that is needed to properly vent a complete bathroom (as long as three inch minimum vent out the roof already)

Hopefully that answerd questions... fire away if you have more... Mark

If this answer helped, please RATE THIS ANSWER. Thank you

.

Hi Brett:

Let me see if I get this. That 3" cast iron drain comes out of floor and then reduces to 2" galvanized pipe and then runs upstairs to bathroom..right?
This pipe sounds like a waste line to me...need to open the wall upstairs and see where it goes...If waste..do not cut into it. If just connects into the vents upstairs, your plumber should be able to connect onto it as a vent without doing anything upstairs (all work would be in basement)...but only if that galvi. pipe is a vent (I doubt it).

Anyway, you said connect into vent at upstairs bathroom by connecting above the flood level rim of the sink...THAT IS CORRECT...want to connect at minimum 6" above the flood level rim..ok? A 2" pvc vent pipe is all that is needed to properly vent a complete bathroom (as long as three inch minimum vent out the roof already)

Hopefully that answerd questions...fire away if you have more...Mark

If this answer helped, please RATE THIS ANSWER. Thank you

.

Hi Massplumber,

Thanks for the answer! I've included a picture this time around. (I'm very proud of it, I did it in MS paint.) It might be 4" cast iron, but I know it's at least 3" since a toilet drains into it. And the galvanized vent may be 3", but I'm not sure until I can get up to the roof and measure it. (it's still a little icy here in Southern Maine). I think you've answered my question though, I've just got to verify that the galvanized pipe is 3", and then I can safely tie into it with 2" PVC. If it's not 3", I guess I'll run a new 2" pipe to the basement from the roof. In the picture, I show what I can see from the basement. As far as I know, nothing actually drains into the galvanized portion of the pipe, so it's a pure vent. I guess it's classified as a wet vent since it connects directly to the stack.

Hey Brett:

Do you have another stack in the house that goes out the roof full size 3 or 4"?

Because I think you have 3" cast iron pipe here (in your pic.) and then it reduces to 2" galvanized pipe/vent going up (3" galvanized pipe is very rare.. so doubt it is 3"..but never know..huh??..Let me know when you get there (will measure almost 3" across) ).

No problem connecting into the 2" (or 3"?) galvanized pipe at six inches above flood level rim of 1st floor sink and sending 2" pvc pipe down to basement for the bathroom vent.

You will want to be careful of the weight of the vent pipe when you cut into it... and use shielded couplings as in my pic. Below (available at home supply or at plumbing supply house) to transition between galvanized and pvc.. ok?

Keep me posted.

Where in Southern Maine? I was in Portland for 5 years (Home of the GREAT LOST BEAR RESTAURANT? ) and Cape Elizabeth for 5 years... Portland Head light is awesome this time of year! Moved back to Boston for school/family... but always miss Maine!

Talk soon... Mark

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Hey Brett:

Do you have another stack in the house that goes out the roof full size 3 or 4"?

Because I think you have 3" cast iron pipe here (in your pic.) and then it reduces to 2" galvanized pipe/vent going up (3" galvanized pipe is very rare..so doubt it is 3"..but never know..huh??..Let me know when you get there (will measure almost 3" across) ).

No problem connecting into the 2" (or 3"?) galvinized pipe at six inches above flood level rim of 1st floor sink and sending 2" pvc pipe down to basement for the bathroom vent.

You will want to be careful of the weight of the vent pipe when you cut into it...and use shielded couplings as in my pic. below (available at home supply or at plumbing supply house) to transition between galvinized and pvc..ok?

Keep me posted.

Where in Southern Maine? I was in Portland for 5 years (Home of the GREAT LOST BEAR RESTAURANT??) and Cape Elizabeth for 5 years...Portland Head light is awesome this time of year!! Moved back to Boston for school/family...but always miss Maine!

Talk soon...Mark

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There's another vent stack that connects to the kitchen sink drain and out through the roof, but it's 1.5". The cast iron stack in my picture is the only one that everything drains into. I have a ranch with an unfinished basement, so it's easy to tell where all the drain lines are that come from the main floor. I'll probably try and get a ladder out to get on the roof over the weekend. I can finally see some grass in my front yard, so that's a positive thing. When I open the wall in the bathroom, I was planning on cutting the galvanized out and replacing it with PVC all the way up through the roof. Seems like it might be easier to do that than have to worry about supporting heavy metal pipe. But if I do decide to keep the galvanized, I'll look for the clamp you recommend.

I live in South Portland near the golf course. I work in Portland though, right near St. John street. Never been to Great Lost bear, but I've heard about it and driven past it many times. I'm not from here originally, but my wife is from the Oxford Hills area.

Sounds like you have a plan Brett. And sounds like that pipe may be 3" as it is code that all homes must have 1 full size vent penetrating the roof....other vents can connect into it, or other vents can penetrate the roof (2" minimum).

Also, note that when installing the fitting for the basement vent into the galvanized pipe you will want to turn the vent fitting upside down... right? And vent pipes pitch back toward drain... That all make sense?

And the great lost bear... make the greatest fajitas in the world! Great burgers, too! Hey let us know how it goes... Mark

Hi Mark,

Yep, I've got a remodel plumbing book along with the Black and Decker plumbing book, so I did know about the backward fitting and that a vent pitches up on a horizontal run. :) I think it could be 3", but I'll verify it when I check. The house was built in 1965, so I assume it complied with code back then.

I like fajitas and any other Mexican food. Maybe I'll try the Great Lost Bear sometime. I've heard about their burgers mostly. There's a good Mexican place in Westbrook now, you should check it out if you ever get back to this area. But I imagine there's a ton of good stuff in Mass too.


Sounds like you have a plan Brett. And sounds like that pipe may be 3" as it is code that all homes must have 1 full size vent penetrating the roof....other vents can connect into it, or other vents can penetrate the roof (2" minimum).

Also, note that when installing the fitting for the basement vent into the galvinized pipe you will want to turn the vent fitting upside down...right? And vent pipes pitch back toward drain...That all make sense??

And the great lost bear...make the greatest fajitas in the world!! Great burgers, too!! Hey let us know how it goes...Mark

Hi again, Mark.

I'm wondering if I might be able to do the plumbing for this project. I've had a plan done for a while, but I started thinking about it more and realized that maybe I can handle doing the plumbing too. It doesn't seem that difficult for this particular situation. When the plumber came over, he found what he called a "short pipe", which is about a foot away from where the first wall will be. The short pipe is a 4" cast iron pipe that is currently plugged with a test cap. When it's opened, there's a strong smell of sewer gas. When the plumber was there, I also asked him about using some sort of backwater valve, since we're on a combined sewer in my area, and I want to be safe against any possible backups from heavy storms. He said he could install a check valve.

I'm uploading a picture that shows my current plan. The red lines are drainage, and the blue lines are vents. Would this work? I really don't want to spend $1000 to have a plumber do this work, but then again, I'd rather have it done properly so that's why I'm asking if this is correct. And what are your thoughts on a check valve or backwater valve? Thanks for your help!

Hey Brett... I have a few issues with your plan.

You do not need to individually vent all 3 fixtures... can use a wet vent for toilet using either shower or lavatory vent to do it.

I would install 3x2 wye for lavatory just behind toilet elbow and run the 2" sink drain into the wall behind sink...stub out 1.5" for sink... continue 2" vent all the way to where it will connect into 2" vent or larger upstairs or in attic (this will act as a vent for the toilet as well). Then in this case, I would install another 3x2 wye BEHIND the sink's 3x2 wye and run 2" over to the ptrap for the tub (reduce to 1.5" out of ptrap to pick up tub waste and overflow assembly), In this 2" run to trap install a 2" sanitary tee fitting (rolled above centerline of waste line) and run 2" vent into/up the tub wall...to act as vent for tub.

As tub vent comes out of ground reduce to 1.5" and connect into the 2" vent from the sink. From there, run 2" to where vent can connect 2" vent or larger.

Wye fittings only for waste (only tee fitting here is for shower vent and at vertical where sink pipe is stubbed out for sink).

45s good

short pattern 90s are bad

Long sweep 90s when come out of ground (or 2 45s)

Back water valves are great as long as accessible for future!


Hope that made sense... get back to me with any questions... Mark

Wow, thanks for the detailed help! After reading your response, I now realize that I don't even want to attempt doing this job. I think I'll stick with just running a vent downstairs, and I'll pay the money to have a plumber do the work. I'm sure that if I could actually comprehend all of what you typed, I could do it. But I can't, so I won't.

And even though I'm cheap in general, I'd rather just pay the money and not have to worry about it. :) I'm just an IT guy that enjoys doing stuff around the house. I know I can handle framing the bathroom and running supply lines, etc. but I'll let a professional with experience and training deal with the drainage.

Thanks again for your help though, it's been very valuable!


Hey Brett...I have a few issues with your plan.

You do not need to individually vent all 3 fixtures...can use a wet vent for toilet using either shower or lavatory vent to do it.

I would install 3x2 wye for lavatory just behind toilet elbow and run the 2" sink drain into the wall behind sink...stub out 1.5" for sink...continue 2" vent all the way to where it will connect into 2" vent or larger upstairs or in attic (this will act as a vent for the toilet as well). Then in this case, I would install another 3x2 wye BEHIND the sink's 3x2 wye and run 2" over to the ptrap for the tub (reduce to 1.5" out of ptrap to pick up tub waste and overflow assembly), In this 2" run to trap install a 2" sanitary tee fitting (rolled above centerline of waste line) and run 2" vent into/up the tub wall...to act as vent for tub.

As tub vent comes out of ground reduce to 1.5" and connect into the 2" vent from the sink. From there, run 2" to where vent can connect 2" vent or larger.

Wye fittings only for waste (only tee fitting here is for shower vent and at vertical where sink pipe is stubbed out for sink).

45s good

short pattern 90s are bad

Long sweep 90s when come out of ground (or 2 45s)

Back water valves are great as long as accessible for future!!

Hope that made sense...get back to me with any questions...Mark

Hello again Mark,

It's obviously been over a year since this was originally posted. Since that time, I ended up redoing the upstairs bathroom first, and while I was at it I added a new 2" PVC vent down to the basement that's been capped off. So the vent is now available.

So, I'm resurrecting this post because I want to do a basement bathroom this summer.

However, I'll still a little confused about your most recent answer. Can you clarify where the 3 x 2" wyes should be placed? I'm uploading a new drawing that only has drain lines (in red). If you mark it up in MS Paint or something and show me where the vent fittings should go, I think it would make more sense to me. Last time I said I was giving up and was going to have a plumber do it, but I know I can do this as long as I can visualize it.

Thank you in advance.

IF you could swap places with the toilet and lavatory you could save running a vent on your tub, (it's unvented in your drawing), and connect to the lavatory drain where it would be wet vented. The lavatory could then revent back to the vent stack, (providing there's nothing draining above it) and your bathroom group would be vented. Good luck, tom

Hi Brett...

Check out my drawing below...

I would install 3x2 wye for lavatory just behind toilet elbow and run the 2" sink drain into the wall behind sink...stub out 1.5" for sink... continue 2" vent all the way to where it will connect into 2" vent or larger upstairs or in attic (this will act as a vent for the toilet as well).

The lavatory vent will act as a vent for itself and as a wet vent for the toilet and the tub... ;)

Otherwise, if the joists don't line up well for this layout, as TOM suggested, move the toilet over where the lav. Is and you should be all set as mentioned.

MARK

Hi Tom and Mark,

Thanks for the quick replies! I think I get it now that it's been drawn out for me. I'll probably post some pictures when I actually do it to make sure it's the way it should be, but at least now I have a good understanding of what to do.

I should be able to leave the sink and toilet in the original locations because the vent can easily run in the wall behind the sink to feed to the location that you indicated. I'll hopefully be starting this in the next 2 months, so I'll post again when I start working on the drainage plumbing. I really appreciate the help!

would the vent tie in above the sink stub-out and then also connect to the 2" wet vent you indicated, or can I just run the 1.5" sink drain into the wet-vent? No~! The line above the sink is a vent while the line below the stub out is the drain. The vent from the sink will run out the roof or tie back into another roof vent in the attic. Then sink drain will tie into the shower/tub and then connect to the toilet branch. I'll put up a more simple wet vent so you can see, Good luck, Tom

Thanks for the reply, Tom. I figured what you said was the way to do it, but wanted to make sure. Once I get the floor opened up (probably in mid-October) I'll post some pictures to make sure I'm doing things the correct way.

Once I get the floor opened up (probably in mid-October) I'll post some pictures Before you start tearing up floors make a drawing that we can check out and advise. Cheers, n Tom