"Kranselag" - a tree or a wreath on a new building

A kranselag somewhere else in Norway.

Every day I pass a construction site of a new big institution.
Now, the roof is ready, so a little tree was placed on the top of the new building.
Sometimes it can also be a wreath.

I remember this tradition from my childhood in Norway. It is supposed to be a very old tradition:
When the owner of the new house sees that the carpenters have done a good job , he makes a little party for them at the building site - in the old days often with lots of alcohol, these days more with a meal and perhaps a bottle of alcohol to bring home.

Often friends and neighbours are also invited - this is a joyous occassion with good hopes for the life in the house soon to be lived in.

Then if the carpenters are happy with the treatment they have gotten from the owner, they put up the little tree or a wreath on the top of the new house.
If they are not, I read they would hang a kind of big scarecrow up there.
I have never seen such a big cloth puppet in my life. Only small trees. Many small trees, over the years.

Imagine starting your life in a house where the carpenters had not been happy.....

There wasn't too much written about this tradition on Norwegian websites, but it turns out the Germans have a Richtfest that is so similiar it makes you believe this is a very old Germanic tradition, before Christianity - but that is just a guess frim my side.