Key:building

The building Key is used to mark areas as a building.

Tagging

The most used tag scheme is simply building=yes.

It is common to use building=<building typology> if you have this information. Renderers are free to support these or just treat them as synonyms for building=yes.

Another tagging scheme is building=yes, building:use=*, for example building=yes, building:use=residential. Please do not use building=<building function>. A list of some building types can be found in wikipedia

The following list contains commenly used values. The possible collisions still have to be discussed.

Key	Value	Element	Comment	Photo
building	church		A church, has to be completed with amenity=place_of_worship, religion=* and denomination=*
building	collapsed		A collapsed building which has to be rebuild.
building	commercial		A building where commercial activities take place. Probably used with shop=*.
building	detached
building	entrance		An entrance in a building, usefull for big buildings.
building	farm		A house on a farm, use building=hangar if it's for storing goods.
building	garage		A garage building. The tag building=garages is also commenly used. (tagwatch)
building	greenhouse		A greenhouse used to grow plants. Use landuse=greenhouse_horticulture for the area where the greenhouses are (inculding water bassins)
building	hangar		Used for storing goods.
building	house		A house where a family lives.
building	hut		A small building where people live, without walls in stone.
building	industrial		Use landuse=industrial for the area. Collision with building=manufacture?
building	manufacture		Factory
building	office		An office. The tags building=Office and building=offices are also used.
building	public		A where you may enter almost publicly like a townhall.
building	residential		collision with building=house?
building	retail
building	school		School buildings.
building	service
building	storage_tank		Used for storing fluids.
building	terrasse
building	transportation
building	university		A university building. Completed with the tag amenity=university.
building	way

How to map

These are some considerations how to trace buildings if you want to do a really good job:

• You should try to trace not the whole block but identify singular parts of the buildings with the same height and roof. This allows for much better visualization, e.g. when someone tries to build a 3D-model of the city. It is also nice to try to identify different properties and use a separate way for each of them (often you can recognize their dividing walls on the roofs as well).
• When tracing from aerial imagery, don't trace the roofs but the building position on the ground. Usually aerial images are not taken from a perfectly vertical position and therefore the walls are visible dependent on the distance of the center of the original camera to the object. This also affects bridges when mapping roads and in general all features higher than ground level. Try to see walls and where they touch the ground in order to get good alignment. If you know the roof is all at the same level, you can trace the roof and then move the outline to match the visible parts of the bottom.
• Connect adjacent buildings, when they are connected in the real world.

in JOSM

• You can make existing buildings look a little better by orthogonalizing them in JOSM. This may make them have odd angles but usually works pretty good. Please be aware that not all buildings are orthogonal and sometimes it is better to keep an odd looking polygon instead of making a curved shape rectangular.

• The buildings plugin makes mapping of buildings a lot more convenient (hotkey w). This works best for buildings with four nodes.

in Potlatch

In Potlach, you can add several buildings quickly especially in residential areas by tracing the building with one hand with the mouse and then with the other hand pressing the 'R' key to add the properties of the previously selected building. Add the source, building tag and whatever other tag you want on the first building then copy it to the other buildings.

Some ways to get the outline of the building

• Aerial photographs (e.g. Yahoo! Aerial Imagery or OpenAerialMap).
• Observations from street level, drawing a sketch, or even taking measurements
• Walking around the edge of the building taking a GPS trace. Good enough for big buildings (e.g. a stadium) but being close to walls is bad for GPS accuracy.
• French Cadastre

See also

• shop=* (to indicate that the building is used as a specific shop)
• amenity=* (to describe what the building is used for, for example: school, theatre, bank, ...)
• building=entrance (to mark the entrances to the building)
• Proposed features/Building - original proposal, which mentions various other ideas
• Proposed features/Building attributes - attributes proposal
• Relations/Proposed/Buildings - (to group buildings and other related things together)
• Please consider adding house numbers to buildings with tags in addr:*=*-Namespace:

addr:street=*

addr:housenumber=*

addr:postcode=*

...

(more values and detailed information here: Key:addr)

Some Examples

• 

  Sutton Coldfield rendered by mapnik ([1])

• 

  Sutton Coldfield rendered by osmarender ([2])