After reading a bunch of questions and answers on this forum, I think that I need to use a riser clamp.

My problem is that I have been unable to find a riser clamp at the local home improvement stores. Do "riser clamps" have a different name? Or are they relatively uncommon (i.e. not stocked at home improvement mega-shops) and I'll need to go to a plumbing supply shop?

Background: I have a 3-inch main waste/vent pumping stack. Given the condition of the existing plumbing (poor) and the fact that I want to add a new bathroom, I've reached the conclusion that it'll be easiest to remove about 75% of my cast iron stack. Before I do this, though, I want to be sure that it's supported properly before I start taking it apart.

Thanks for your help! This site is AWESOME!!

Do "riser clamps" have a different name? Or are they relatively uncommon (i.e. not stocked at home improvement mega-shops) and I'll need to go to a plumbing supply shop?
Big box stores don't handle heavy construction stuff like raiser clamps,(see image) you will have to go to a plumbing store or a wholesale house to pick one up. When I cut into a vertical cast iron stack I use a set of ratchet chain cutters to make the cut and a raiser clamp and two bumper jacks to prop up the pipe. Good luck, Tom

Thanks Tom.

I've already called the plumbing supply store and they have it.