We’ve attempted to be green with this house renovation, reusing our materials where possible–we even saved the 2x4s from our demo to re-use in the new framing. Accordingly, we had planned our new kitchen to incorporate the existing soil pipe and vent stack. This drain stack was cast iron, which is much better for sound insulation than modern-day PVC. But alas, our kitchen design changed, and we needed to rotate a section of the drain stack in order to tie in some new plumbing.
At first, we thought we could just rotate the four-inch sanitary tee, but it soon became apparent that these stacked pieces of pipe were immovable. Around the same time, we rethought our kitchen design and decided it might be beneficial to move the 2nd story of the drain stack. Thus we decided to take down the soil pipe to the gap between the downstairs ceiling and the upstairs floor.
We needed to get the vent out of the roof before the roofing contractor comes in, so we rented a chain cutter and began cutting through our soil pipe up near the roof. Aaron made the first cut while I stabilized the pipe above the cut. We were really afraid that it was going to weigh 100 lbs and come crashing down on one of our faces, but it ended up being (A) a manageable weight and (B) stable, even after the cut. With the first piece out, we continued moving down the pipe.
Some of the pipe fittings felt loose, and we thought maybe we could drill them out and lift the pipes out of place, but…no luck. And so it was back to the chain cutter. There was a section, five feet or so and running from the second floor down to the middle of the first floor, which consisted completely of short fittings. We were going to try to cut just under the sanitary tee, but there were so many hubs and bends and turns that the chain cutter wouldn’t fit, so we had to go down to the next straight section of pipe, which was about six feet up from the ground in the first story. We were slowly losing all of our precious cast iron!
We cut through the pipe and gently lowered the (very heavy) bendy section to the ground using an elaborate pulley system devised by Aaron. We were all done and ready to cap the line when we noticed a crack in the pipe, starting about a foot above the floor. This section, too, would have to go.
Once again, we were at it with the chain cutter, taking away more pipe than we’d originally planned on. We were cutting about 8 inches above the slab foundation at this point, when a chunk of the pipe collapsed in and left a gaping hole in the pipe. So much for salvaging our cast iron pipe; we cut it off at the base using the Sawzall.
Upon inspecting the cross-section of the cut-off pipe, it appears to have been a manufacturing defect; one side (the side with the crack) is considerably thinner than the other. This isn’t a problem with modern cast iron, but the manufacturing process was a little unreliable back in the day, so the older stuff can be prone to this. Or so we hear from unverifiable, un-sited internet sources.
At the end of the day, we’d taken all the cast iron out down to the slab. We think the remaining pipe will be all right as it is only three inches long and entirely encased in concrete. Looks like PVC plumbing for us, afterall.