attic vs mansard roof

attic

noun
  • The space, often unfinished and with sloped walls, directly below the roof in the uppermost part of a house or other building, generally used for storage or habitation. 

  • A person's head or brain. 

mansard roof

noun
  • A roof having two slopes on each side, the lower one having a steeper pitch than the upper; this increases the volume of the enclosed space. 

  • A steeper roof that terminates into a flat roof at its high point. 

How often have the words attic and mansard roof occurred in a corpus of books? (source: Google Ngram Viewer )