|Proposal status:||Inactive (inactive)|
Please note, that beside the original proposal, the tag has gained importance and use in modelling Simple_3D_Buildings, see also below and on the main page.
Original 2007 Proposal
A raw idea on the modelling of complex buildings.
Buildings can still be modelled as closed ways (areas) with building=yes (this is setting area=yes as default too), or marked as a node, or a group of nodes without areas.
However a relation can be used to group them all together and make it clear that this stuff belongs to one building. Also some interesting things about a building, like entrances, shops or postal addresses can be included. (The fact that an entrance belongs to a certain building may be easy to guess in most cases but not e.g. for underground station entrances).
If you have a complex of more than one building, you should use a relation for each building and put them all into Relations/Proposed/Site.
Postal Address Information:
This subject is not easy. First take a look onto Karlsruhe_Schema. If you want to tag addresses onto buildings take a look at the following suggestions.
If possible tag the entrances with their address.
If there is a single address and one or more entrances, then tag the main entrance or the "wall" of the building.
If there are more addresses then entrances, set single nodes for each address near the entrance the addresses belongs to. Put these nodes and the entrances in single relations for each entrance. Than put these address relations into the building relation as members with role address (see the Members section below).
Sometimes it is not easy to see to which street a building (or its adresses / housenumbers) belongs to, for example at street corners. In this situation it could be helpful to set single nodes with the address / housenumber near the correct street. Such nodes should be put into the building relation as members with role address (see the Members section below).
It is very important to use your brain to decide if or which suggestion make sense. You are the one who knows the local situation. It can make sense to combine suggestions or find some new scheme.
|Way, Node, Area or Relation||Role||Recurrence?||Discussion|
|outline||zero or more||The areas that make up the building walls. Other names? Maybe just "wall"?|
|label||zero or one||This should be used to set the name of the building and to tag the whole building as a POI if desired. The idea behind this is, that this mark should tell the renderer where the name and maybe the symbol of the building should be displayed. That could be necessary if the building includes many details.
This single node could be used also to mark a building if the walls can not be drawn.
|entrance||zero or more||Entrances into the building. Big entrances could be areas, but mostly a single node is enough. They might have to be individually tagged as to what kind of entrance they are. There are existing some proposals for entrances (examples:Proposed features/entrance, Tag:railway=subway entrance), so tag it as you like.
Also entrances can be used to tag different adresses of a building. See section "Postal Address Information" above.
|contains||zero or more||This should be used for POIs inside a building. If you have detailed information of such POI (separate entrance, different address or something like that), you should better build a separate building relation for each POI and than put this relations as members in right here.|
|address||zero or more||This should be used for nodes and relations, who were only tagged with address informations. See section "Postal Address Information" above.|
Current usage in 3D modelling
In the course of developing tools and maps for 3D representation from OSM data a relation with type=building has been suggested. As of 2014-12-12 exist about 6000 relations with type=building in the OSM data (source taginfo). Some of those are used to relate building:parts=yes, roof:ridges=yes and roof:edge=yes to a building outline. Details about Simple_3D_Buildings.