Today the builders put the soil stack in from the top floor bathroom down to the basement. Here you can see how the suspended ceilings work to allow pipe runs through the building:

In rooms which don't have the original decorative ceiling cornices, we are installing suspended ceilings (plasterboard and timber studwork) below the original ceilings. This creates a free route for pipe and cable runs, which both speeds installation and reduces the amount of notching/drilling of load-bearing elements.

Bathroom areas will be ventilated using single-room MVHR units (see this article for a more detailed explanation), mounted within the suspended ceiling voids...