Run this after the shelf wall demo — once the plumbing is exposed. Nick supplies the adapter and hose. Text results when done.
If backup occurs
Shut it off immediately and text Nick.
Remove cleanout cap on both ends of cast iron stack
Right back room near electrical panel
Connect garden hose via adapter Nick provides — bathroom supply valve to cleanout (~6-8 ft)
Run water for several minutes — watch both ends for flow and no backup
Drains freely at outside cleanout, no gurgling inside = good.
Text Nick results — flowed freely? Any backup? How long?