I own a 1942 bungalow with a single 1st floor bathroom. I would like to add a 1/2 bath to the 2nd floor. The vent from the basement/1st floor passes through the upstairs bedroom. The stack is behind a plaster 'bump out' on an exterior wall that is about 16" wide and 3" deep.

Whether I do the work myself or hire a plumber, I would just like to get a feel for what this would take. Obviously I will need to run copper from the basement to the 2nd floor. I am assuming I can run both lines up the same path as the vent, space permitting. The 1st floor bathroom is directly below where I would like the bathroom on the 2nd floor.

The drainage and venting is where I become confused. I have been reading other messages about how to avoid running a second, dedicated vent through the roof just for the 2nd floor bath, but it is still unclear to me. Do I run a second vent from above the 1st floor sewer connection to a spot on the existing vent above the 2nd floor sewer connection? Is this called 'reventing'?

Like I said, I'm just trying to get a feel for the size of the job. I will obviously need to study up on plumbing and code, if and when I decide to take on this project. Hiring a plumber is probably as wiser idea.

Thanks!

I did the same thing you are now contemplating. In laymans terms: I opened up the water wall in my downstairs bath. Where the vents (ALL of them) tied into the main stack, I cut them off and extended them into my attic and tied them back into the main stack. (you must tie them back in 6" above your sink's rim). Right below where the vents tied into the stack on the first floor, I cut off the cast iron stack all the way to the roof and converted to PVC. Tie in all your 2nd floor units as normal, making sure they drain/vent as code permits. This is a big project and I have some tips for you.

1) plumb in the drain/vent first. They receive precedent because drains are powered by gravity. i.e. they have a limited # of places they can go. Then plumb supplies.

2) listen to any and everything that labman (TOM) has to say. His word is gospel. To defy or reject anything he says is just plain dumb and your project will likely have negative outcomes.

3) refer to #2

Good luck

Louie

Thanks Louie,( Attic Guy) for those nice words in (2) but I'm not Labman I'm speedball1 but Labman thanks you also.

If the vent from the first floor bath is at least three inches then you may cut in a sanitary tee and discharge the second floor bathroom into that. If not you'll have to run a 3" drain up to pick up the second floor bathroom group. You'll vent the group off the lavatory and tie back,(revent) to the main vent in the attic. However, that's assuming the first floor vent's three inches or over. If it is you're home free on the second floor drain and vent. What you can not do is discharge the second floor bathroom group past the firdst floor without first giving it a proper vent. You must disconnect the first floor lavatory vent from the 3" line that's now the second floor drain and run a 2" vent up past the second floor bathroom group and revent back in the attic to the main vent going out the roof.
If this sounds complicated and a lot of hassle, that's because it is. Installing a bathroom group over another bath group's major surgery and unless you have plumbing skills best to contract the job out. I didn't mention the water pipe because that's a breeze compared to the drains and vents. Good luck, Tom

Sorry, TOM aka speedball. I guess I see so much of you two around here - I got mixed up.

Anywho- LISTEN TO SPEEDBALL about plumbing, he's the man.

Also, listen to labman - he's got his head on straight and knows a lot about a lot. Plus he's a chemist, so I have to give him a tilt of the hat. (I'm a chemist also)


Louie (atticguy)