We have an older house with plastered walls. Our vertical sewer pipe is cast iron and badly cracked. We will have to open the wall in the bathroom where the pipes run to replace the vent pipe. Is it possible to push pvc pipe into the old cast iron pipe from above? We are trying to avoid opening the wall in the room below. The cracked pipe is 4 inch cast iron pipe.

Possible maybe, but wrong and not to code. Buy a Fernco connector and open the wall just enough to install it and tighten the clamps, maybe about 6" sq.

Duchessssoho, you can use a fernco clamp as presented by joypulv, BUT you must make sure that the fernco clamp is a PVC x cast iron SHIELDED CLAMP (see image) to handle the compressive load placed on it from the vertical piping. The all rubber/neoprene fernco with 2 SS clamps are not for this job... ;)

How are you planning to cut out the 4" cast iron pipe? You are planning on supporting your piping from below... right? Cutting into a vertical cast iron stack can be very dangerous work so please post back and discuss this with us in more detail, OK?


Mark