I have a hopefully not too stupid question about replacing part of my cast iron sewer stack.

I have a 50+ year old house with roots in my sewer pipe causing some backup thought the basement drain. I used root killer in the drain and several weeks later had a mat of small roots flush back up through the drain. I rented two different sewer cleaning machines, and could not get either one to go down into the sewer. The 4 inch clean-out at the bottom of the stack was appropriated by a previous owner to connect two plastic sewer pipes for two additional stools. They put in a new clean-out plug, but it is 3 feet and two bends back from the iron pipe. The cutter end goes into the iron pipe and hits the other side. I could not get either of them to drop down into the pipe itself.

I presume I would be wasting my money calling a plumber as they most likely could not get their machine to go into the sewer either. I think the exterior sewer pipe is tile, but do not know for sure. Two of my neighbors know their pipe is tile. I would like to have a video camera examination of the pipe where the roots are to see if I need to have it dug up and replaced. Again, I would hate to call someone in and find they cannot get into the pipe for examination, and have to pay them for nothing.

There is a short piece of iron pipe connected to the section going into the floor with a 1 ½ inch threaded hole in it which is used to connect to the washer. The washer drains into a 2 inch plastic pipe, which is connected to the 1 ½ in hole using a reducer. If I run a full load of laundry, waste water will frequently overflow from the 2 inch pipe because, I presume, it is backing up at the 1 ½ inch hole.

I would like to remove this lower piece of pipe with the 1 ½ inch hole and cut off an additional section of the drain pipe above it. I would then install a new cast-iron section with a 4 inch access hole, and a second section with a 2 or 3 inch hole to provide an adequate drain for the washer. My question is (finally), can I cut out a chunk of the existing stack and install two new hubbed sections of cast iron pipe in the middle of the existing stack? Are the hub lengths such that a new section of pipe can be slipped in, pushed up and then sealed with oakum and lead? I would think the upper sections would tend to push the pipe all the way to the bottom of the hub, causing a joint to eventually open up somewhere higher up.

The stack comes down through the middle of the house and then runs horizontally to the back wall of the basement where it drops down through the floor. The vertical pipe is tied to the underside of the floor joists with heavy iron straps, though they do not appear to be that tight. I think most of the horizontal run is being supported by the back wall vertical sections. There are 2 3-foot sections of 4 inch iron pipe above the smaller piece with the 1 ½ inch hole.

I’ve determined from reading other plumbing advice that I would need to adequately support the existing sewer stack while a lower section is removed.

Any advice would be appreciated.

This can be accomplished much better using No-Hub fittings and bands. The way you explain the washer hook up there's no trap or vent involved. Mealy a direct connection between the sewer and your home allowing sewer gas to enter it. I suggest cuttng in a 4" cleanout tee and under that a 4 X 2" drainage tee running into a upright tee to run a vent off from through the roof or revented back into a dry vent. After the vent tee a 2" trap with a 36" stand pipe for the washer. You will need to support the vertical stack when you cut into it. I use a raiser clamp and two bumper jacks to secure the stack until I can get the fittings installed. If you need more instruction on how to do this click on back and I'll walk you through the process. Good luck, Tom

Thanks Tom,

I will look into No-Hub fittings. There is a p-trap in the washer drain line. There is about 2 feet of vertical plastic pipe, then a p-trap and then a straight run of 2 feet or so over to the dran into the stack. There is no vent of any kind. I will look into installing one with the new fittings. Thanks for the jack suggestion also.

Thanks, Gene

Hey Gene,

Let me show you No-Hub Clamps and a raiser clamp in case you're wondering what they are. Regards, Tom