office-house

noun1

1. •
   (no longer used) A building or outhouse on a farm, estate, manor, palace, etc. used for household work, storage, housing servants, etc; the office of the steward or bailiff on a manor or estate; a house of office.

   • That gloomy spot they spoke of lay aside from the hamlet. In a dell, begirt with firs, you might behold a hut, and various ruined office-houses. — 1827