Cast Iron Vent Problem/Replacement

[fishfun83]

My son has a sink that is backing up. At the same time the sink backs up, he noticed water on the floor of the adjoining bedroom. When he looked into the wall separating the bathroom and the bedroom where the water came from, it was obvious that a cast iron vent pipe that goes through the roof was cracked at a transition from 3 inch PVC to cast iron for several feet. (see photos) Our thinking is to remove the 3 inch rubber transition clamp, pull the cast iron pipe up and through the roof, snake out the vent line and under floor line, and replace the entire cast iron section with PVC.

Any comments on our plan? Is there something else we should consider?

 

[bbp]

Your right on, careful though, its going to be heavy and you may need to enlarge the hole in the roof to get the cast iron hub through.

 

[fishfun83]

Hopefully this is just a straight section of 3 inch CI pipe with no hub. I fugure it is going to weigh about 80 pounds and is going to be rather awkward getting it straight out of the roof penetration. We might want to consider making a thru cut in the CI pipe in the attic so it is not so heavy and make it a little easier to get out. Thanks for your input.

 

[Helper Dave]

Yeah, if you have the access to a safe place to do so, like the attic, either cut the pipe, or (easier yet), just whack at it with a little maul. They crack easier than they cut.

 

[Geofd]

Yeah, if you have the access to a safe place to do so, like the attic, either cut the pipe, or (easier yet), just whack at it with a little maul. They crack easier than they cut.

Use a couple of friction clamps one to pull up with and the other to secure on the floor so yo7 can cut into manageable sections

 

[packardv8]

just whack at it with a little maul. They crack easier than they cut.

Use a couple of friction clamps one to pull up with and the other to secure on the floor so yo7 can cut into manageable sections

X2 - Cast iron is a ***** to cut, but easy to break.

OT, but plumbing related; a plumber friend was asked to do some relatively minor remodeling work which included removing a built-in cast iron bath tub in a second-floor bath. He hemmed and hawed about how difficult this was going to be and how he'd have to call in a special crew to get it out and down the stairs. The homeowners said, "Well, do what you've got to do and let us know how much it's going to cost." While they were gone for the day, he brought up his 8# sledge, broke the tub in pieces small enough to throw out the window and put them in his pickup to haul to the scrap yard. Knowing how is profitable.

jack vines

 

[Jeff Handy]

Like Geofd was saying, if there is room in the attic, I would try to avoid having to work on the roof, and you would then probably need to install a new vent pipe boot and do some shingle repairs etc.

Break off sections that you can pull out in the attic, and slowly pull it all up.

Support the hanging cast with clamps, maybe two in case one pooped out and the stack dropped.

Just leave a stub of cast to attach to going out of the roof.

Would a chain cutter work for demo like this?

You could drop new pvc vent down in sections.

I have done similar repairs taking out failed galvanized or copper drains that run through lots of floor joists, doing all the work from one hole in the ceiling.