Then you should have a protected shaft as every floor is a compartment floor. The problem is not the absence of Fire resistance between rooms, its the lack of a properly protected shaft, and is much more significant but I am afraid all too common. Most student accommodation and many hotels being built today use bathroom pods in which the bathroom pod forms two sides of what should be a protected shaft. If you are lucky it will be as substantial as 18mm plywood - but often it is just GRP. The biggest frustration is that the big AIs dont seem to think it a problem. I have found several cases in timber framed buildings in which to make matters worse there was also an open cavity between the plasterboard ceilings and the timber floor, open to the risers at each floor level. One of these recently had been approved by a local authority BCO as well. The owner spent over ?100K to sort that one out as the buildier had gone bust. In come cases you can seal across the floor at each storey but sometimes all you can do is list it as a risk in the FRA where the recommendations will just gather dust till one day a coroner will have cause to ask relevant questions.