When my boss was a child he stayed at a historic mansion in or around Oslo, Norway. He believes is used to be a royal cabin and it was made of teak wood. It had over 10 bedrooms and had an indoor steam room on top of an underground spring. It had large fireplaces at least 6' tall. He thinks it used to be a hunting lodge for the royal family. He believes he stayed there in the 1960's and it was used by the military (Airforce?) for their families to stay and vacation. He also thinks the town and lodge are near a hollowed out mountain that was used by the military. It would have been like an underground city inside the mountain. I hope someone can tell me the name of the lodge and where it is located. Thanks!

Kolsas Leir was a NATO base in Kolsas, Norway until 1994. I don't see anything about the teak royal cabin, yet.

Royalinsight.net has pictures of all the current royal residences, and one is wood but many more than 10 bedrooms.
The area of Norway around the NATO base is now a very expensive bedroom community around Oslo and it's possible that the teak mansion in now privately owned.