mansard vs porch

mansard

noun
  • The upper storey of a building, surrounded by such a roof 

  • A mansard roof 

adj
  • having two slopes on each side, the lower being steeper than the upper 

porch

noun
  • A portico; a covered walk. 

  • A covered entrance to a building, whether taken from the interior, and forming a sort of vestibule within the main wall, or projecting without and with a separate roof. A porch often has chair(s), table(s) and swings. 

  • The platform outside the external hatch of a spacecraft. 

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