Since moving house a few years ago, we can never decide whether we now have a loft or an attic! The space under our roof is very large and we have lots of stuff up there, so we always lean towards attic, as this sounds more like a room and less like storage space.
I decided it was time to investigate the origins of the two words and discovered the following: Loft entered our language with the Vikings. The word comes from the Old Norse Lopt, meaning 'upper chamber, region of sky, or air', and the Old English loft means pretty much the same thing, but leaning slightly towards the 'air/sky' than the upper chamber. Did the Anglo-Saxons even have upper chambers? The word Attic comes from the practice of decorating the top of facades in the style of Attic architecture.
It would seem logical therefore, to think of our upper rooms as a loft rather than an attic, but we still don't feel that this is conclusive.
However, if the Anglo-Saxons did have a room at the top of their houses stuffed full with junk they might need one day or can't bear to part with, and this doesn't seem very likely, it's more likely to have been a loft than an attic!
We continue to prevaricate, and call the rooms both attic and loft!