Abstract: A frame structure formed of a plurality of parallelly disposed rafter bars having axially connected thereto, a plurality of bow members forming the rear wall. The edges of said rafter bars are connected to a ridge bar and supported above ground level by uprights connected thereto in the vicinity of said ridge bar and the ends of said bow members being set in base plates on the ground, and a covering shaped to fit over said frame structure. Various cross bars and supports may be provided.