I need to make some changes to a 4" drain pipe in the basement of my house. This pipe connects to a toilet on the 2nd floor and extends out the roof as a vent - straight pipe from basement to roof.

Work had been previously done on this pipe, so it extend about a foot below the first floor into basement where it is joined with a flexible coupling.

I want to remove that coupling, however, I'm unsure as to what is supporting the pipe above.

How are these pipes typically supported?

I'm thinking of using some sort of clamp and hanging from floor joists.

Any suggestions on ways to support this pipe?

speedball1

To support a vertical raiser when making a cut we place a raiser clamp,(see image) above the cut and a bumper jack under each ear of the clamp.
Good luck, tom