I don't have this data at hand, and often it's hard to see from out front or differs for different parts of the building. So while an avid OpenStreetMap contributor, I rarely add height info to buildings
Perhaps I should look into high resolution height data (that is, high enough that an individual building shows up at all) with licenses that allow use in OSM and at least tag the buildings that show having a mostly uniform height. For example in the Netherlands, AHN is amazing (hundreds of points per tree! It looks like a 3d wireframe render of the entire country, truly amazing) but the license is not permissive enough.
Perhaps I should look into high resolution height data (that is, high enough that an individual building shows up at all) with licenses that allow use in OSM and at least tag the buildings that show having a mostly uniform height. For example in the Netherlands, AHN is amazing (hundreds of points per tree! It looks like a 3d wireframe render of the entire country, truly amazing) but the license is not permissive enough.