I plan to put an ensuite wc in an attic room,with an internal soil stack capped with an air admittance valve.I could take the pipe through a wall ,just below the eaves,joining the existing soil stick there.I would prefer to pass the pipe through the bathroom ceiling(below) and then join with the existing WC waste.
I would be grateful for any advice you can give please.
I would be grateful for any advice you can give please.