View Full Version : Replacing Main Stack

10-27-2009, 03:19 PM
I'm going to be pulling out my existing cast iron stack and replacing with ABS, but I'm not sure of how I would connect this to the existing sewer main. The cast iron runs into our concrete floor in the basement, and then to the street. What is the best thing to do in this case? Should I remove the stack as close to the ground as possible and then use a no-hub coupling to join the new ABS to the existing CI, or should I jackhammer out the concrete? Kind of lost here - suggestions?

Peter Griffin
10-27-2009, 03:55 PM
Use a mission band coupling which is pretty similar to a no-hub coupling but made for what you are doing. I like the 4 banded ones. Do not use an un-banded Fernco

10-27-2009, 04:06 PM
Cool - but should I completely remove the CI below the slab, or should I just remove it right above the slab and use a coupling to join the existing and new DWV lines?

Peter Griffin
10-27-2009, 05:05 PM
4" above the floor would be fine. Be sure to replace the clean out at that point.

Gary Swart
10-27-2009, 05:20 PM
Before you remove that CI and replace it with ABS or PVC, you should consider the fact that either of these mediums are quite noisy when water passes through them and there will be little you can do about it. Cast iron is difficult for DIYers to work with, but unless you don't care about the noise, you might be wise to back off removing it. Hiring a plumber to work with the CI might be worth the expense over the long term.

10-27-2009, 05:38 PM
I'm not too concerned about the noise as the drain lines will only be from the first floor into the basement, and the drains themselves will already be in the basement. As for the vent lines, they will be buried in the walls surrounded by insulation.

So I'm not too worried about the CI, but I appreciate the heads up. I've read about the noise issues of ABS compared to CI in other columns; however, when you compare the ease of use (and repair) of ABS versus CI, I'll take ABS any day (especially being a near full time DIY).