Key:min height

For marking height top part of building (building=*) or part of building (building:part=yes) above ground level we use tag height=*. If building or part of building starts not from the ground level, we should use tag min_height=* for describing height of bottom part of building or part of building. By default meaning is counted in meters.

If you know number of levels of building or part of building above the ground level, it is also useful to add tag building:levels=* (and building:min_level=*, if the bottom level of building or part of building is not located on the ground).

A common mistake when mapping elevated structures is to set height=* to the effective height, subtracting the bottom from the top. In fact, height=* is supposed to be the height at the top compared to ground level, irrespective of min_height=*. This Sophox query finds buildings that are effectively "upside-down" because of this mistake.

Minimum height of people to use the feature

Some facilities (e.g. ski lifts, theme park rides) have a "minimum height requirement", as in "You must be X m tall to use it". min_height=* could be used to record this information. As of 13 October 2019 the tag is used this way 129 times, mostly on roller coasters and water slides. This usage is problematic because an object can be some distance above ground level and require a minimum height for riders. See also: min_age=*, max_age=*, suggestion on the talk-gb mailing list.