I have inherited a DIY project and have some questions regarding the whys and wherefores of routing waste pipes around the bathroom. You can see from the attached doc that we plan to install a bath, basin, shower and toilet, with a pre-existing waste pipe fitted into the corner of the room, which runs to a vertical stack, via another bathroom, some 4m away.
Can I simply run one waste pipe from the bath, via the basin, then to the shower, combining all 3 wastes into one, then under the doorway to the main waste pipe, into which the toilet is plumbed? Or do I need separate pipes for any appliances?
I need to cross the joists at some point - do I simply notch them or should I be drilling holes?
Will I have flow problems, given that the total run is going to be in the region of 6m?