I have ripped out a downstairs shower room, the floor was basically unstable and floating because all the drainage had been run joist height, a complete mess. Basically it connects to a vent that runs into an adjacent room which has a dergo. If I can do away with this connection to the vent pipe and re route the drainage to toilet, I can re joist and make a stable floor. They have a second bathroom on the first floor which has a vent running up past the guttering. Am I right in thinking that as long As the first floor bathroom has a vent stack that the downstairs wastes can be pipes straight in to the ground floor drain?