If the old apartments in Germany are anything like those in Belgium, the inside walls are probably plastered brick (or worse - concrete). Wooden houses are a rarity here. Living in old buildings I've never encountered one of these walls built around a wooden frame.
By the way : concrete isn't bad as you think. There are different type of concrete.But... While it's strong and resistant to fire, if you live in somewhere where the earth quakes are common, concrete is a bad choice. Also metal frames in the concrete is problematic, they have to be resistant to the water (galvanized etc.) or in time they will rust and tear apart the concrete.
In Norway and Sweden we also have mostly wooden houses. I would imagine it's the same in Finland as well. Probably because we have lots and lots of trees here, compared to continental Europe.
