I'm a plumbing novice, though I can do all the finish stuff. Never done the work behind the walls. Last year we bought a house built in 1925. The third floor walk-up attic is in excellent shape. I plan to finish it this summer.
I can see the (probably cast iron) vent pipe coming up in the rafters and through the roof. I'm pretty sure I'd have pretty good access to that pipe (and maybe the hot/cold lines as well) because the second floor bathroom wall backs up to my closet. I'm not really sure what I'm supposed to do.
A cursory search for "how-to" videos seems to indicate that I need to cut a segment out of that vent pipe and add a split onto it so the attic toilet, shower, and sink would all drain there. Then I would need to find the hot an cold lines and also add splits onto them so I could run lines up to the attic.
Questions:
1) Is the vent pipe I see in my attic also the main drain line I tap into for attic toilet, shower, and sink?
2) Do I split the hot/cold lines from current plumbing into a single hot and a single cold line going to the attic and from there split it off for the shower, faucet, and toilet?
3) Am I missing other major steps in this process?

Thanks everyone!

Hi Gdsov

1) You CANNOT connect your attic drain into the cast iron vent pipe in any way! Here, that vent stack acts to vent the first floor as well as the second floor plumbing fixtures...can't connect a waste pipe into it in any way. Instead, you'll need to determine if the second floor plumbing connects to the 1st floor plumbing...if it does, then you need to run a 3" pipe from the basement up and into the attic. Once that waste pipe is into the attic you'll pick up the drains and vent the fixtures according to local code requirements. The vents from the bathroom can connect together at a minimum height of 42" off the floor and then you can connect that vent into the main vent stack just before it goes out the roof.

2) It depends on what size the water lines are now and exactly how many fixtures total are being served by those pipes. What size is your water main?

3) Yup...probably, but start with that information and get back to us with your thoughts.

We are glad to discuss more if you like, OK?

Mark

Mark, Thanks for the response. Without further inspection, I'm pretty sure everything is stacked. One 2nd floor bathroom right above the kitchen, and the laundry room is right below it. I've had a licensed plumber in my attic and he didn't mention anything about a line to the basement. He also looked at the vent pipe (I assume that's what it was--I'm now doubting what I thought I understood from him) that is exposed in the attic and talked about how he would have to cut it. If the water main is the water line that comes into the house then the outside diameter is 7/8". I need it to serve a shower, toilet, and faucet in the attic. What I have easy access to is the hot and cold lines going to my second floor shower. I thought about tapping into those if there wasn't a problem with doing so.Thanks for the info!Greg

Water is not an issue. You have 3/4 copper(? ), measures 7/8 OD, which can be extended by soldering or, if exposed, by using Shark or Gator bite fittings and PEX or CPVC. That is the easy part. Drains and venting are the issue. If the drains and vents are in a chase, you may have clearance to run to the attic. Can you see how the drain lines run to the 2nd floor?

ma0641, until I get the chance to search more for the drain/vent answers, I should note that the 7/8" OD line I mentioned was the main coming into the house. The hot and cold lines I'd be tapping into aren't 7/8" OD. They look like the regular diameter you might see coming into a sink cabinet.Does that make a difference in your answer about water supply to the sink, toilet, shower in the attic?Greg

Something not mentioned... most localities require permits for this sort of work to be done. Do you have one?

To the permit question… Not yet. I'm only in the VERY beginning stages of the project. (I've really only cleared out boxes and swept the attic!) Knowing what the project will entail will determine if I can do it or if I need to hire it out, which in turn affects budget. If I can't do it myself (and since I can't afford to hire that job out right now), I won't need to pull a permit.

I just checked… the hot and cold lines I'd like to use are 5/8" OD and leading to the second floor shower. Will that supply enough water pressure to a third floor/attic bath?

I'd check with your local building department to start here. Most building departments have a check list and helpful resources to aid you so you don't end up getting surprised (alot).For example, most, if not all states that I know, will NOT let a homeowner pull a plumbing permit. In cases where the homeowner wants to do the plumbing work they are required to find a plumber that will pull the permit and stand for inspection (not easy and usually expensive). This also usually means that that plumber will want to design the layout. Funny, most states will allow a homeowner to pull a building and an electrical permit, but homeowners can't pull a gas or plumbing permit. I can understand the gas, but I always found it funny that homeowners can electrocute themselves or burn their buildings down messing with electricity, but they can't install a pipe over to a toilet (I do understand why they don't want homeowners messing with water heaters and other dangerous plumbing work).

Anyway, the 5/8" lines are probably 1/2" copper tubing and it is typically a reasonable size to feed a single bathroom and have good pressure. With that being said, however, the issue will not be one of pressure when someone is up and showering on the third floor it will be one of VOLUME where that person showering will see a drop in volume/pressure when someone uses another fixture in the bathroom below. To straighten this out you would send new 1/2" CPVC or PEX water pipes up to the bathroom from the basement. You would connect these pipes in the basement to the 3/4" hot and cold lines if you did not want to see a VOLUME drop/change at the shower upstairs when the project is finished!Finally, I really think we can do more harm than good in some ways on this subject (DRAIN/VENT) as each state and heck, each town/city has an inspector that wants things done his/her way, so you really should consult a local plumber or two, for sure!

Mark