I have recently started adding details to building in accordance with the Simple 3D Buildings guideline, to make their 3D models, in apps that render those, look more like their real-world counterparts.
I have a couple of buildings in my area which aren’t very tall yet have large elevator/stairwell bulkheads on top (these things), making those visible from the street level. But, I have no idea how to map them.
I want to create a building:part on the roof for the elevator/stairwell bulkhead, but what do I enter in terms of floors? In order for it to be visible on a 3D model, it needs to have one level more than the rest of the building, but strictly speaking, an elevator bulkhead isn’t really a livable/usable floor (outside of for maintenance and roof access activities). Do I mark it as a roof:levels=1 perhaps?
Plant room, machine room or lift over-run would be what I would call it. That said, some elevators (up to a few storeys high) are hydraulic and their machine rooms tend to be at ground level. Roof-top plant rooms can also have things like water tanks and air conditioning equipment, but these are often in a separate physical room.
What you can do is set the (approximate) height of the main roof and then a higher value for the height of the plant room roof.
In this row of neighbourhood shops: Way: 106358513 | OpenStreetMap all the shops are single storey, so I have set building=retail, building:levels=1, height=4. Storey heights in retail buildings tend to be taller than those in residential ones.
However, in the centre of the building, there is an upstairs hair / beauty salon: Way: 1491635640 | OpenStreetMap so I have set building:part=retail, building:levels=2, height=8.
Then, above the salon is a small room for water tanks: Way: 1491635650 | OpenStreetMap that I have set to building:part=yes and height=10. I have not set building:levels=*.
So, in this view: F4map Demo - Interactive 3D map the plantroom (slightly different colour to the rest of the roof) can be seen sticking 2 metres (10-8=2) above the salon roof.
Next door to the shops is a library. In this case, the plantroom appears to be a proper room: Way: 1491851503 | OpenStreetMap so I have set building:levels=3, building:part=library and height=11.
