I am a fairly new mapper from the Netherlands who just recently saw many houses are not in the Norwegian OSM. Some of them do have the address markers but not the building polygons while others aren’t included at all. I would love to help mapping these buildings correctly, but it seems the main issue is lack of properly aligned aerial imagery. As I’m not fluent in Norwegian (“maybe understand the gist of a simple sentence”-not-fluent), I was having trouble browsing the list of imagery sources. Also, I would like to know if there might be some project going on (or being in the making) that is going to map these houses, or if someone is currently busy getting better image sources.
There exists some official data with buildings for the entire country (search the mailing list for “FKB” and “bygningsomriss”), but it’s not yet publicly available. When this is made publicly available, a semi-automatic import can be done. Others can probably fill in more details.
Yes, waiting is probably a good idea at this time. The Norwegian Mapping Authority (http://www.kartverket.no) put out a plan several years ago for when they intended to release various types of data. They have stuck to the plan so far. Since then, 2017 has been the year when the FKB data were to be released, so let us hope they still stick to the plan.
It should be said that releasing the FKB data is quite a bit more complicated than the rest of the data. This is because the mapping authority does not own the rights to data alone - the individual municipalities have ownership to the data. Of course this was known already when the original plan was made, and this is probably why they planned to release this data after all the other “easier” data was released.