Hello all,

We have an old brick chimney that was at one point (before our time) decommissioned and repurposed as a furnace vent using a flexible chimney liner inside. When we bought our home, the chimney was sticking up through the roof, and the chimney liner went up through a metal flat top and ended with a simple rain cap.

However, due to some safety concerns with the external section of the chimney (chimney was leaning above roof line), we have demoed it below the roofline and it now ends inside our attic just below the inside of the roof.

Now, we want to connect the flexible chimney liner to a simple B-vent pipe that will come up through the roof.

Can anyone tell me what kind of connection piece(s) I will need to connect the existing flexible chimney liner to the b-vent that will run above the roof? I know that there needs to be a flashing piece on top of the roof, with the b-vent pipe sticking up through it, terminating with a rain cap. But I'm just not sure how to connect the flexible liner to the b-vent pipe underneath the roof/inside our attic.

If anyone needs help visually understanding what we want to end up with, I found this youtube video that shows what we want, but unfortunately this person's setup is a little different than ours in that he's not using a chimney liner to begin with (his whole setup is rigid b-vent from the start).

https://www.youtube.com/watch?app=desktop&v=4zAGgGeBaUM

Thank you for any help you can provide!