as an architect exchanging models in IFC with other consultants, I came across a topic that got me wondered… this is my first post here, so here I go
I am talking about the IFC4 IfcBuildingStory. In the documentation it is defined that this parameter is related to the upper edge of the constructive slab, therefore resulting in a negative value when we are speaking about the ground floor. Until now I was working with IFC2x3 and in my authoring tool I was defining this parameter to the upper edge of the finishing floor, which at the same time was ±0,00m. On the other hand, the agreed story names and their numerical heights are documented in the BEP. All changes happening to the composition of the slab did not have any influence on the IfcBuildingStory, because the story values stayed the same (story nett height changed). Only if the planning team decided to lower the storey height, only then action was needed resulting in changes in the numerical story value. According to the IFC4 when for example, some layers of the finishing floor change thickness, this automatically impacts the numerical value of IfcBuildingStory, because it will shift upwards or downwards the constructive slab (preconditioned my finishing upper edge must remain the same).
Therefore, I am questioning the validity and usability of the IfcBuildingStory being referenced to the constructive element of the slab and not the finishing layer, in this case the ±0,00m.
Can someone explain this to me please…