mansard roof

/M AE1 N S ER0 D R UW0 F/
noun
  1. 1

    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.

  2. 2

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

Source: https://en.wiktionary.org/wiki/mansard%20roof