Spain was neutral during WW1 and WW2. They did have a big civil war, but that was less destructive than WW2 (still very bad though, just not nearly as bad as WW2).
For Germany it might be the reason: Lots of large German cities were mostly destroyed, some practically entirely + they had a large amount of refugees from east of the Oder that needed new places to live.
This level of destruction was not/much less the case in France and Italy. A quick google search says that France actually lost less housing stock during ww2 than Britain did. britannica.com/…/casualties-of-World-War-II-22310…