|building = terrace|
|The outline of a linear row of residential dwellings, each of which normally has its own entrance, which form a terrace ("row-house" or "townhouse" in North American English).|
|Used on these elements|
|Status: in use|
|Tools for this tag|
This tag is most commonly used as a less-detailed option to define the outline of a linear row of residential dwellings which form a terrace. Each of the dwellings normally has its own entrance. These are known as "rowhouse" or "townhouse" in North American English.
As often in OSM there are multiple correct ways to map a given situation.
Another more detailed approach is to map each dwelling separately using building=house, but keeping at least two nodes in common for adjoining houses. This is more appropriate for cases where it is clearly several independent buildings that happen to share walls, but may have been built at different times, by different builders, with different styles, etc, and where each building is maintained separately from the others. When using this method house=terraced can be put on the individual units.
A third approach is to tag the outline of the entire physical structure with building=terrace, and inside the outline, draw the borders of each individual dwelling and tag it with building:part=house (and optionally, you may add each dwelling's border and the building outline together in a type=building relation). This approach may be more appropriate for cases where it is very clear that the building is all one cohesive unit, built at the same time by the same builder, in the same style, and may share critical structural features with the adjoining units. It may also be more appropriate for cases where the entire physical structure has important metadata that all the units inside of it share, such as a building name.
Which of the two more detailed approaches applies is not always clear cut, as it can be up to interpretation whether each dwelling is "its own building." Use your best judgment.
This tag is not meant to be used for a platform that extends outwards from a building.
How to map
Draw a single area along the outline of the whole terrace. Optionally add entrance=* for each entrance. If the borders of each dwelling of the terrace is known, add areas inside of the building for each of the dwellings and tag them with building:part=house, and any other tags specific to each dwelling, such as addr:unit=*. Optionally, add each dwelling's area and the building outline together in a type=building relation.