Repair for Stinky Cracked Cast Iron Drain

Some friends of mine just bought a new house full of old cast iron. During the home inspection, the inspector warned them that it was getting older and should be closely watched and possibly replaced.

Wouldn't you know that within a week of them moving in one of the 4" cast iron drain pipes in the basement developed a huge crack in one of the sections coming from the master bath. Unfortunately they didn't notice until the next day and their basement was wet.

I was asked to repair the pipe while they consider just replacing it all.

The basic idea of this repair was to remove the busted pipe and replace it with PVC. Here's the process:

1. Before cutting out the damaged section, make sure that there are supports in the appropriate places so that no pieces of cast iron come crashing down on you. Also, make sure to have a bucket ready in case some of the stinky stuff leaks out.

2. I used my reciprocal saw with a carbide-tipped blade to cut through a 2" drain and the 4" drain. Because of the cracks location I would have to replace a T and part of the intersecting lines.

3. I took one end of the damaged pipe apart at the hub. I first used a sledgehammer to break apart the already cracked pipe back to the hub. Then, with a few careful blows I was able to get the hub to crack and I knocked it off. The lead joint compound came off with my cold chisel.

4. Dry fit the PVC parts together to make sure it will fit. Where the PVC joins the cast iron I used the appropriate rubber coupling. Then, once I knew the pieces fit, I glued it all together on the floor.

5. Slide the PVC into place and join to the cast iron using rubber couplings.

6. Check for leaks and clean up.

The hardest part of it is probably cutting out the damaged section. PVC is generally easy to work with, especially when you're just replacing a a section like I was.

Oh yeah, #7. Go take a shower to get the stink off...

-Peter

www.CarpentryGuy.com