PROBLEM TO BE SOLVED: To provide a roof ventilation apparatus for a greenhouse applicable to an existing greenhouse as well as a newly-built greenhouse. SOLUTION: A plurality of A-framed units 6 are arranged in a row, the bottom of each A-framed unit is connected to a common sheet-fixing member, and a common head board 9 is connected to the ridges of the units to form a roof truss unit. At least one roof truss unit is placed at the top of the greenhouse roof and a bottom sheet-fixing member 7 is connected to the frame of the greenhouse. A covering sheet 29 of the greenhouse is fixed by using a sheet-fixing groove of the head board 9 of the roof truss unit and the sheet-fixing member 7 of the bottom part. An end of the covering sheet 29 is fixed to at least one of the sheet-fixing groove of the head board 9, the sheet is rolled down along the inclined face and the other end of the sheet is wound around a winding shaft extended in the direction of the ridge. The apparatus is further provided with a rotation driving means 32 to open or close an opening between the head board 9 of the roof truss and the sheet-fixing member 7 by the rotation of the winding shaft. COPYRIGHT: (C)2005,JPO&NCIPI
