We bought last year an apartment of the 1st floor. The building has garages and utility rooms right under our level and the two bedrooms face north. One of the bedrooms has actually an external wall ...
This winter in the attic I noticed ice on the roofing nails. Obviously warm moist air condensed and then froze on the cold nails. When the weather broke and warmed up a bit, I was back up in the attic ...