Elk is using openstreetmap data. Look on openstreetmap.com if the height of the building is available. If it is, then there is something wrong in your definition.
In my experience, if you are extracting data of a small town / city, most of the time you wont have building heights. An actually, there is no way around this… except doing it manually (collect data manually; THEN if you want you can construct a shapefile from that collected info).
Ask yourself what you really need to. In most cases doing it manually is, in 2019, faster then finding the data you need online. Free and accessible GIS data are often incomplete…
It is not solved but I am understand thank you!!
Also note that sometimes buildings don’t have height data but number of floors. That could help some in cases where that data is available…
See here for an explanation of the number of levels in the basement, building and roof: