Is there a way to do address interpolation on buildings?

Hi TheAdventurer64, you can encode address interpolations into the OSM database using the following technique:

• Create a node for the lowest-numbered address, tagged with addr:street and addr:housenumber. (Other addr:* tags can be added too.)
• Create a similar node for the highest-numbered address
• Draw a linear way from the low-numbered address node to the high-numbered address node, and add a addr:interpolation tag to that way, with an appropriate value.

The most common values for addr:interpolation are "even", (meaning all even-numbered addresses that fall between the low number and high number will be found along this way), "odd", (meaning all odd-numbered addresses that fall between the low and high number will be found along this way) and "all" (meaning all addresses between the low and high number will be found along this way, for roads that don't put the even numbers on one side and the odd numbers on another or if you don't know what side the houses are on).

Here's an example:

• the low-numbered address node
• the high-numbered address node
• the interpolation way drawn between them

You can read more about this on the wiki: https://wiki.openstreetmap.org/wiki/Addresses#Using_interpolation.

Generally this technique is used for preliminary mapping. Once more precise locations for each address can be mapped, the addr:interpolation way can be deleted from the database.

Have a look here https://wiki.openstreetmap.org/wiki/Proposed_features/House_numbers/Karlsruhe_Schema

The easiest way to do it is using StreetComplete, as this shows the buildings with known numbers and asks you for the number of any unknown buildings, with handy +/- buttons. However this makes you a naughty boy, because StreetComplete is for surveying areas, not armchair mapping.