My kitchen sink drain is cast iron. And my problem is, is that it drops down into the basement, below my joists and then does a straight diagonal bee line to the drain stack. Right where it is located is where we walk to get to the washer and dryer and I have to duck because of it. Plus, I want to finish the basement and put a door there. So my question is, can I have the drain pipe drop within the joist cavity, have it run parallel (sloped) across the basement, therefore above the beam and then drop it below the joists, and use an elbow to have it run parallel to the beam and to the stack? This will allow me to get it out of the way first off, but also on the other side, I will be able to install suspended ceiling, because the drain pipe will be within the beam height. Plus I'm going to replace the pipe with ABS. I've attached pictures, thanks!

Hi Kingsmax...

I see no issues with what you present... ;)

There are some requirements, like long sweep elbows, cleanouts, proper transition clamps, etc. and we are glad to help lay it out if you like...

Back to you...

MARK

Okay, that's great! Where would you put the clean outs? And also, that pipe goes into the wall cavity on the main floor. Under the sink is ABS, but it connects to this pipe inside that wall. Should I just cut the metal pipe where I want to add the ABS, or should I gut the wall? I'd rather not gut the wall if possible. Also, what is the best method for cutting that old pipe and fixing ABS to it? And lastly (sorry for all the questions) what would be the best method to re-attach the ABS to that stack? The stack is also iron, and I want to replace it, but that's another day!

Hi Kingsx:

You will cut the galvanized pipe using a sawzall (reciprocating saw) with bimetal blades. You will cut the galvanized pipe about 3 inches off the cast iron stack and cut the galvanized pipe on the other end about 2" below the floor.

Then you will install shielded or mission clamps to transition over to the ABS plastic pipe... see image. Do not use the all rubber type of clamps... not meant for this application (see 2nd image).

You will install a clamp and then a long sweep elbow up in the joist bay and run the pipe in the joist bay over toward the cast iron stack. At the cast iron stack you will install the clamp and a 45 degree fitting to square the new piping up to the insulated heat pipe in the picture. Then you want to install a DANDY CLEAN OUT (also called a test tee fitting)... see 3rd image.

As you come out of the joist bay, use a long sweep 90 rolled at a 45 degree angle to meet up with a 45 degree fitting from the pipe at the cast iron end of this.

The pipes need to be hung every 4 feet and should be pitched at 1/4" per foot of pipe... ;) You could also add a cleanout up in the joist bay as code wants a cleanout at every change of direction, but that's up to you. Let me know if all this made sense?

Purchase a coupling and a couple 22.5 degree fittings just in case you need to make any adjustments to join/align pipes.

MARK

Thanks Mark for your awesome assistance! So I use one long sweep elbow below the drain, and then another one when I have to go perpendicular to the joists towards the stack. And then a 45 degree to meet back up with the stack. I'm pretty sure I follow you.

Exactly! :)

As you come out of the joist bay to run perpendicular to the joists that long sweep will need to join a 45 degree fitting to bring it into line with the pipe from the cast iron stack. There will also be a 45 degree fitting at the cast iron stack to straighten the run.

..

Thanks Mark, I do have another question. As I sit, I realize more questions keep coming up. Anyway, when I slope the pipe, is it a matter of just sloping it properly and then using ABS cement to make the connection? What I mean is, the drain that comes from the sink is straight up and down, if I use a 90 degree on it, the pipe that would run from there, should run straight with no slope. Do I just create the slope by letting it "sag" so to speak?

And hkstroud, I'm not sure I what you mean? I'm not sure if your arrow is pointing to the joist, or the toilet drain?

Toilet drain, just wondering if you could tie into that and stay completely above joist. How many joist would you have to drill to do so?

If I could tie into the toilet drain, that'll give me even more head room so to speak. But I don't have to drill into the joists. I just need the drain pipe to be within the beam height. Right now, the pipe is below the beam and in the way. So basically I'll travel inside the joist bay, but then once on the other side of the beam, I'll drop it down and then go to the stack below the joists, but inside and perpendicular to the beam. I will probably have to do another 90 degrees once I reach the stack and go down to the original drain location. If I'm making sense that is...

Edit: I just re-read your post hk, and although from the pictures point of view it looks like the toilet drain is in the joist cavity, it actually isn't. Its right below the joists. But still within the beam height.

My point exactly, maybe you could tie into toilet. Slope of pipe should be 1/4 per foot.

Well either way, it'll be better than it is right now. I'll have to look into the toilet option. It might be a bigger job than I might want to tackle right now?