View Full Version : Cutting into DWV Stack

01-19-2007, 07:05 AM
I am remodeling my single story house with raised foundation. My house is 40 ft wide with a foundation wall every ten feet to hold the floor joists. The main stack goes through two of these walls to receive waste. The second wall apparently was repaired around the stack because the stack seems to be cemented in place rather than simply going through a hole in the wall. Hence my problem.

I have to cut into the stack in order to reconfigure a bathroom. I don't have any way to move the two ends to insert a standard glued coupling, and so I believe the proper way to install the new fittings/pipes is to use rubber couplings, one or two as necessary. Is this correct or is there a more suitable, code-worthy solution?

01-19-2007, 10:06 AM
The easier way is to use the banded repair couplings - these have a neoprene sleeve with a metal reinforced band around them and a hose clamp on each end. They work fine and are code complient. They also make a repair coupling, which looks like a normal coupling until you view the inside - it does not have a ridge to limit the pipe insertion. On this, timing is critical since you slide it totally on one pipe, align the other then slide it back before the glue sets ending with the coupling approximately centered over the joint.

01-19-2007, 11:14 AM
To easily use the banded coupling... slip the metal sleeve over the pipe and then put the rubber gasket on the pipe end...
Fold it back over itself so that it does not overhang the end of the existing pipe... When the new pipe is in place, unfold the rubber gasket so it covers the joint and slip the band back over then tighten to 60 in/lb torque (5 ft/lb)...

For the plastic repair coupling, to ensure coupling gets centered on joint, make a mark 6" back from joint on one of the pipes...
When sliding the coupling back over joint, ensure middle of coupling is 6" from mark - saves from having to wonder if coupling is centered... For the plastic coupling, use plenty of glue, bevel the ends of the pipes to be joined, and work quickly...

01-19-2007, 03:08 PM
When using normal couplings, it's a pretty tight fit just getting the coupling to dry fit onto a pipe. Are the repair couplings a little more generous in this respect, or is that where the bevel comes in?

01-19-2007, 06:26 PM
No, because if they had more "slop" the joint would be less than perfect. Beveling will let you aim the pipe and start it into the coupling easier, but unless your cement is slow setting, you may not be able to position it in time. Especially since you will have to do two ends, and you have to cement the inside of the coupling before you slide it on.