Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
upstairs [ʌpˈstɛəz] adv (be) наверху́; (go) наве́рх
adj (window, room) ве́рхний#
n ве́рхний*эта́ж#
there's no upstairs здесь нет ве́рхнего этажа́
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.
Русский: